SCANPSC100FMW [TI]

SPECIALTY MICROPROCESSOR CIRCUIT, PDSO28, SOIC-28;


型号：	SCANPSC100FMW
厂家：	TEXAS INSTRUMENTS
描述：	SPECIALTY MICROPROCESSOR CIRCUIT, PDSO28, SOIC-28 光电二极管外围集成电路
文件：	总29页 (文件大小：416K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

September 1998

SCANPSC100F

Embedded Boundary Scan Controller

(IEEE 1149.1 Support)

General Description

Features

n Compatible with IEEE Std. 1149.1 (JTAG) Test Access

Port and Boundary Scan Architecture

The SCANPSC100F is designed to interface a generic paral-

lel processor bus to a serial scan test bus. It is useful in im-

proving scan throughput when applying serial vectors to sys-

tem test circuitry and reduces the software overhead that is

associated with applying serial patterns with a parallel pro-

cessor. The ’PSC100F operates by serializing data from the

parallel bus for shifting through the chain of 1149.1 compliant

components (i.e., scan chain). Scan data returning from the

scan chain is placed on the parallel port to be read by the

host processor. Up to two scan chains can be directly con-

trolled with the ’PSC100F via two independent TMS pins.

Scan control is supplied with user specific patterns which

makes the ’PSC100F protocol-independent. Overflow and

underflow conditions are prevented by stopping the test

clock. A 32-bit counter is used to program the number of TCK

cycles required to complete a scan operation within the

boundary scan chain or to complete a ’PSC100F Built-In Self

Test (BIST) operation. SCANPSC100F device drivers and

1149.1 embedded test application code are available with

National’s SCANEase software tools.

n Supported by National’s SCAN Ease (Embedded

Application Software Enabler) Software

n Uses generic, asynchronous processor interface;

compatible with a wide range of processors and PCLK

frequencies

n Directly supports up to two 1149.1 scan chains

n 16-bit Serial Signature Compaction (SSC) at the Test

Data In (TDI) port

n Automatically produces pseudo-random patterns at the

Test Data Out (TDO) port

n Fabricated on FACT 1.5 µm CMOS process

n Supports 1149.1 test clock (TCK) frequencies up to

25 MHz

n TTL-compatible inputs; full-swing CMOS outputs with

24 mA source/sink capability

™

n Standard Microcircuit Drawing (SMD) 5962-9475001

Connection Diagrams

28-Pin DIP and Flatpak

Pin Assignment for LCC

DS100325-18

DS100325-1

™

FACT is a trademark of Fairchild Semiconductor Corporation.

TRI-STATE^®is a registered trademark of National Semiconductor Corporation.

DS100325

www.national.com

provide user specific control data. Test Data In (TDI) re-

ceives serial data from the scan chain. A local control block

is associated with each Shifter/Buffer to provide shift and

load control as well as providing full or empty status. The SSI

also provides Test Clock (TCK) Control. TCK is stopped and

started depending on the status of the Shifter/Buffers or the

32-bit Counter. By stopping and starting TCK, scan opera-

tions will proceed only when the enabled Shifter/Buffers are

ready to send and/or receive serial data.

Chip Architecture

The ’PSC100 is designed to act together with a parallel bus

host as a serial test bus master. Parallel data is written by the

host to the ’PSC100, which serializes the data for application

to a serial test bus. Serial data returning from the target scan

chain(s) is placed on the processor port for parallel reads.

Several features are included in the ’PSC100 which make

scan test communication more convenient and efficient.

Figure 1 shows the major functional blocks of the ’PSC100

design. The Parallel Processor Interface (PPI) is an asyn-

chronous, 8-bit parallel interface which is used by the host

processor to write and read data. The PPI generates the

necessary internal data, address, and control signals to

complete internal write and read operations.

The 32-bit Counter (CNT32) is a count-down binary counter

included to assist in controlling the SSI. The initial state of

CNT32 is loaded from the parallel port with four consecutive

writes to its address. When enabled, CNT32 is used to pro-

gram the number of TCKs applied by the SSI to the bound-

ary scan chain(s). The value of CNT32 can also be used to

generate interrupts (i.e., when CNT32 reaches terminal

count) and to trigger ’PSC100 features, such as, Auto TMS

High (discussed later within this datasheet).

The Serial Scan Interface (SSI) consists of

a bank of

double-buffered parallel/serial shift registers (i.e., a 2 x 8 bit

FIFO), or Shifter/Buffers. The double buffering improves effi-

ciency by allowing parallel writes or reads to/from one of the

two 8-bit FIFOs within the shifter/buffer while the other FIFO

is shifting data to/from the scan chain. Three Shifter/Buffers

are provided for outgoing serial data and one for incoming

serial data. Test Data Out (TDO) is for scanning out test data

while the two Test Mode Select signals (TMS0/1) are used to

The Mode and Status Registers are used to control and ob-

serve the operation of the SSI and CNT32. Each of the

Shifter/Buffers and CNT32 have an associated mode bit

which enables it for participation in on-going operations. Sta-

tus bits can be used for polling operations.

DS100325-2

FIGURE 1. ’PSC100 Block Diagram

Pin Descriptions

Description

Name

RST (Input)

The Reset pin is an asynchronous input that, when low, initializes the ’PSC100. Mode bits, Shifter/Buffer

and CNT32 control logic, TCK Control, and the PPI are all initialized to defined states. RST has hysteresis

for improved noise immunity.

SCK (Input)

OE (Input)

The System Clock drives all internal timing. The test clock, TCK, is a gated and buffered version of SCK.

SCK has hysteresis for improved immunity.

Output Enable TRI-STATEs all SSI outputs when high. A 20 kΩ pull-up resistor is connected to

automatically TRI-STATE^®these outputs when this signal is floating.

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Pin Descriptions (Continued)

Description

Name

CE (Input)

R/W (Input)

STB (Input)

Chip Enable, when low, enables the PPI for byte transfers. D(7:0) and RDY are TRI-STATEd if CE is high.

CE has hysteresis for improved noise immunity.

Read/Write defines a PPI cycle — Read when high, Write when low. R/ W has hysteresis for improved

noise immunity.

Strobe is used for timing all PPI byte transfers. D(7:0) are TRI-STATEd when STB is high. All other PPI

inputs must meet specified setup and hold times with respect to this signal. STB has hysteresis for

improved noise immunity.

A(2:0)

The Address pins are used to select the register to be written to or read from.

(Input)

D(7:0) (I/O)

INT

Bidirectional pins used to transfer parallel data to and from the ’PSC100.

Interrupt is used to trigger a host interrupt for any of the defined interrupt events. INT is active high.

(Output)

RDY

Ready is used to synchronize asynchronous byte transfers between the host and the ’PSC100. When low,

RDY signals that the addressed register is ready to be accessed RDY is enabled when CE is low.

(TRI-STATE

Output)

TDO

Test Data Out is the serial scan output from the ’PSC100. TDO is enabled when OE is low.

(TRI-STATE

Output)

TMS(1:0)

(TRI-STATE

Output)

The Test Mode Select pins are serial outputs used to supply control logic to the UUT. TMS(1:0) are

enabled when OE is low.

TCK

The Test Clock output is a buffered version of SCK for distribution in the UUT. TCK Control logic starts

and stops TCK to prevent overflow and underflow conditions. TCK is enabled when OE is low.

(TRI-STATE

Output)

TDI (Input)

Test Data In is the serial scan input to the ’PSC100. A 20 kΩ pull-up resistor is connected to force TDI to

a logic 1 when the TDO line from the UUT is floating.

FRZ (Input)

The Freeze pin is used to asynchronously generate a user-specific pulse on TCK. If the FRZ Enable Mode

bit is set, TCK will be forced high if FRZ goes high. FRZ has hysteresis for improved noise immunity.

Mode and Status Registers

MODE REGISTER 0 (MODE0)

Bit 7

TDO

Bit 6

TDI

Bit 5

Bit 4

TMS0

Enable

Bit 3

TMS1

Enable

Bit 2

Bit 1

Auto TMS High

Enable

Bit 0

Loop-

CNT32

Enable

Reserved

Around

Enable

This register is purely a mode register. All bits are writeable

and readable. The value 00100000 is placed in this register

upon RST low or a synchronous reset operation.

• Bit 4: This bit enables the TMS0 shifter/buffer for shift op-

erations. If this bit is set, the TMS0 shifter/buffer will

cause TCK to stop if it is empty.

• Bit 7: This bit enables the TDO shifter/buffer for shift op-

erations. If this bit is set, the TDO shifter/buffer will

cause TCK to stop if it is empty.

• Bit 3: This bit enables the TMS1 shifter/buffer for shift op-

erations. If this bit is set, the TMS1 shifter/buffer will

cause TCK to stop if it is empty.

• Bit 6: This bit enables the TDI shifter/buffer for shift op-

erations. If this bit is set, the TDI shifter/buffer will

cause TCK to stop if it is full.

• Bit 2: This bit is reserved and should remain as a logic 0

during all ’PSC100 operations.

• Bit 1: If this bit is set, TMS will be forced high when the

32-bit counter is at state (00000001)h.

• Bit 5: This bit enables the 32-bit counter. If this bit is set,

the counter will cause TCK to stop if if has not been

loaded or if it has reached terminal count.

• Bit 0: This bit causes TDI to be connected directly back

through TDO for Loop-Around operations.

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Mode and Status Registers (Continued)

MODE REGISTER 1 (MODE1)

Bit 7

TDO

Bit 6

TDI

Bit 5

CNT32

Interrupt

Enable

Bit 4

PRPG

Enable

Bit 3

SSC

Bit 2

Freeze

Bit 1

Test

Bit 0

Test

Interrupt

Enable

Interrrupt

Enable

Loop-

Back

Loop-

Back

Enable

This register is purely a mode register. All bits are writeable

and readable. The value 00000000 is placed in this register

upon RST low or a synchronous reset operation.

is reconfigured as a 16-Bit Serial Signature

Compactor. If set, and MODE0 Bit 6 is set,

the TDI shifter/buffer will cause TCK to stop

until a seed value has been written to the

two TDI registers.

• Bit 7:

• Bit 6:

• Bit 5:

• Bit 4:

If this bit is set and the TDO shifter/buffer is

not full (i.e., one or both 8-bit TDO FIFOs

are empty), the INT pin will go high.

• Bit 2:

If this bit is set, a high value on FRZ will

force TCK high (see TCK Control Section).

If this bit is set and the TDI shifter/buffer is

not empty (i.e., one or both 8-bit TDI FIFOs

are full), the INT pin will go high.

• Bits 1 and 0: These bits are used to control

Test Loop-Back operations according to the

following table.

If this bit is set, and the 32-bit counter is not

loaded or has reached terminal count, the

INT pin will go high.

MODE1

Function

Bit 1

Bit 0

This bit signifies that the TD0 shifter/buffer

is reconfigured as a 32-Bit Pseudo Random

Pattern Generator. If set, and MODE0 Bit 7

is set, the TDO shifter/buffer will stop TCK

until a seed value has been written to all

four of the 8-bit LFSR segments.

Normal Operation

Loop-Back TDO to TDI

Loop-Back TMS0 to TDI

Loop Back TMS1 to TDI

• Bit 3:

This bit signifies that the TD1 shifter/buffer

MODE REGISTER 2 (MODE2)

Write:

Bit 7

Not

Bit 6

Not

Bit 5

Not

Bit 4

Not

Bit 3

Bit 2

Update

Status

Bit 1

Bit 0

Continuous

Update

Single

Step

Used

Reset

CNT32

Read:

Bit 7

TDO

Bit 6

TDI

Bit 5

Bit 4

Bit 3

TMS1

Status

Bit 2

Continuous

Update

Bit 1

Bit 0

Single

Step

CNT32

Status

TMS0

Status

Reset

CNT32

This register contains both mode and status bits. Bits 4–7

are status bits only. Bit 3 is a status bit during read opera-

tions and a mode bit during write operations. Bits 0–2 are

mode bits only. Upon RST low, or a synchronous reset, the

value placed in MODE2 is 10111000 (Read mode). Latches

used to update status bits 3–7 retain their last state upon

RST and are in an “unknown” state after power-up. To initial-

ize the latches to a known state, they need to be updated us-

ing the Update Status bit (bit 2) or continuous update bit (bit

3).

• Bit 5: Set high if the 32-bit counter has not been loaded,

or has reached terminal count.

• Bit 4: Set high if the TMS0 shifter/buffer is not full, i.e.,

one or both 8-bit TMS0 FIFOs are ready to be writ-

ten to.

• Bit 3 (Read Cycle):

Set high if the TMS1 shifter/buffer is not full, i.e.,

one or both 8-bit TMS1 FIFOs are ready to be writ-

ten to.

• Bit 3 (Write Cycle):

• Bit 7: Set high if the TDO shifter/buffer is not full, i.e., one

or both 8-bit TDO FIFOs are ready to be written to.

If set, will cause all status bits to be continuously

updated.

• Bit 6: Set high if the TDI shifter/buffer is not empty, i.e.,

one or both 8-bit TDI FIFOs are ready to be read

from.

• Bit 2 (Read Cycle):

Shows the state of the Continuous Update bit dur-

ing read operations (Bit 3 during writes).

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•

MODE1(4:3)

MODE2(0)

Mode and Status Registers (Continued)

• Bit 2 (Write Cycle):

If set, will cause a pulse to be issued internally that

will update all status bits. This bit will be reset upon

completion of the pulse. The state of this bit is not

readable. It is reset upon RST low.

Parallel Processor Interface (PPI)

ADDRESS ASSIGNMENT

The following table defines which register is selected for ac-

cess with the address lines, A(2:0).

• Bit 1: If set, will cause a synchronous reset of all func-

tions except the parallel interface. The value of this

bit will return to zero when the reset operation is

complete.

R/W

Function

TDO Shifter/Buffer

Counter Register 1

TDI Shifter/Buffer

TMS0 Shifter/Buffer

Counter Register 2

TMS1 Shifter/Buffer

Counter Register 3

32-Bit Counter

Counter Register 0

MODE0

• Bit 0: If set, will cause the 32-bit counter to count for one

SCK cycle (no TCK cycle will be generated). The

value of this bit will return to zero when the single

step operation is complete.

PROGRAMMING RESTRICTIONS

Because certain mode bits enable shift operations for certain

functions, these mode bits should not be changed when shift

operations are in progress. The alignment of all registers

during shift operations is controlled by a 3-bit counter in the

TCK control block. Enabling or disabling a function in the

middle of a shift operation may disrupt the logic necessary to

keep all shifter/buffers byte-aligned.

MODE0

For example, if the TDO shifter/buffer (already loaded) is en-

abled while the 3-bit counter value is 3, the shifter/buffer will

only shift out only five bits of the first byte loaded.

MODE1

The following bits should not be changed when shift opera-

tions are in progress, i.e., when TCK is enabled (see section

on TCK Control).

MODE2

•

MODE0(7:3)

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Parallel Processor Interface (PPI) (Continued)

TIMING WAVEFORMS

DS100325-3

FIGURE 2. Write Cycle

DS100325-4

FIGURE 3. Read Cycle

Note 1: Valid data is provided on the RDY line a t

pd1

after R/W is asserted low or a t after valid data is decoded on A2:0. The RDY line will remain high until the

pd2

addressed register is ready to participate in the write operation. This condition only applies when writing to a shifter/buffer and is eliminated (i.e., RDY will go low

immediately once valid) when using shifter/buffer status polling (discussed later in this datasheet).

Note 2: Valid data will not appear on D7:0 (and RDY will remain high) until the addressed register is ready to participate in the read operation. When the addressed

register becomes ready (i.e., a byte is available to be read), valid data will be placed on the D7:0 bus and the RDY pin will go low allowing the bus cycle to continue.

This read cycle delay only applies when reading the TDI shifter/buffer and is eliminated when using shifter/buffer status poling.

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Parallel Processor Interface (PPI) (Continued)

TIMING WAVEFORMS (Continued)

DS100325-5

FIGURE 4. Consecutive Read/Writes (best case timing)

DS100325-6

FIGURE 5. Consecutive Read/Writes (worst case timing)

Note 3: Figures 4, 5: Figure 4 shows the best case bus cycle timing for SCK and STB during consecutive read or write cycles. The rising edge of strobe occurs a

setup time, t or before the falling edge of SCK. This allows the cycle to be completed within 1.5 clock SCK clock cycles. Figure 5 shows the worst case bus cycle

timing for SCK and STB during consecutive read or write cycles. The rising edge of strobe does not meet the t requirement between STB and SCK. Therefore,

the propagation of the internal PSC100 control and reset signals is delayed until the next falling edge of SCK. The bus cycle is then completed 1.5 SCK cycles later

creating a total bus cycle time of 2.5 SCK cycles. If worst case timing is considered for bus cycle timing, t

is not a mandatory timing specification.

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Parallel Processor Interface (PPI) (Continued)

TIMING WAVEFORMS (Continued)

DS100325-20

FIGURE 6. Read/Write or Write/Read (best case timing)

DS100325-7

FIGURE 7. Read/Write or Write/Read (worst case timing)

Note 4: Figures 6, 7: This diagram shows the timing for a read followed by a write (or write followed by a read). Separate Read and Write data/address latches and

control logic allow consecutive read/write or write/read operations to be overlapped (i.e., do not need to wait 2 or 3 SCK cycles between bus cycles). For the best

case timing scenario (Figure 6: rising edge of STB to falling edge of SCK greater than t ), a new bus cycle can be performed each SCK cycle. For the worst timing

scenario (Figure 7: rising edge of STB to falling edge of SCK is less than t ), a one SCK cycle delay must be included after each back to back read/write or write/

read sequence.

Note 5: Figures 4, 5, 6, 7 assume that the PSC100 register participating in the bus cycle is ready to accept/provide data. For bus cycles involving a PSC100 shifter/

buffer(s), the ready status of a shifter/buffer can be checked using the status bits in Mode Register 2 prior to the start of the bus cycle. Polling is required when the

RDY pin is not used to provide a processor “handshake”.

READ AND WRITE CYCLES

dress lines for a valid PSC100F register address. Once a

valid address has been decoded and if the addressed

PSC100F register is ready to be read (see Table 2), valid

data is placed on the Data lines (D7:0) a propagation delay

later and the ready line is asserted low. If the addressed reg-

ister is not ready (e.g., the TDI shifter/buffer is empty), the

ready line will remain high and hold the bus cycle until the

the read cycle to continue. With the high to low edge on RDY

line, the processor can successfully read the valid data.

However, the bus cycle is not completed within the PSC100F

until the rising edge on STB which resets the PSC100F read

logic (required prior to the start of the next read cycle).

A Write cycle (see Figure 2) is initiated by asserting CE and

R/W low followed by a low on STB a set time later. CE and

STB are gated within the PSC100F and may be asserted

concurrently (i.e., zero setup and hold time). The address is

then asserted on A2:0 to indicate which internal address

within the PSC100F will be written to by the processor. An

address decoder within the PSC100F monitors the address

lines for a valid PSC100F register address. Once a valid ad-

dress has been decoded, the RDY line becomes active (a

propagation delay time later). The active RDY line will go low

immediately if the addressed register is ready to accept data.

If the addressed register is not ready, the RDY pin will re-

main high preventing the processor from completing the bus

cycle. Once the register is ready to receive date (see Table

2), the RDY pin will go low and processor can resume the

write cycle. The processor then forces a high on STB (a wait

time after RDY goes low) which latches the address (A2:0)

and data (D7:0) completing the bus cycle. The RDY line is

forced high a propagation delay later.

Important note concerning the use of RDY : The RDY sig-

nal provides a useful “handshake” between the PSC100F

and the processor. However, care must be taken when using

the PSC100F RDY signal to prevent a large (or indefinite)

number of processor generated wait states. For example, if

the TDO shifter/buffer is not enabled for shift operations and

the processor writes to the TDO shifter/buffer address 3

times, the two registers which make up the TDO shifter/

buffer will accept the first two bytes of data, but since the

data is not shifting out, the 3rd byte will be held off by the

RDY signal indefinitely. An equally severe problem could re-

sult with a finite number of wait states if the application uses

A Read cycle (see Figure 3) is initiated by asserting CE low

and R/W high followed by a low on STB a set time later. CE

and STB are gated within the PSC100F and may be as-

serted concurrently (i.e., zero setup and hold time). The ad-

dress bits (A2:0) are then asserted to indicate which internal

address within the PSC100F will be read by the processor.

An address decoder within the PSC100F monitors the ad-

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Consecutive Reads and Writes: Separate control logic and

data/address latches are used for a read and write operation

within the PSC100F. This allows a write to occur after a read

(or conversely, a read to occur after a write) prior to the 1.5/

2.5 SCK clock cycle requirements described above. The tim-

ing for a read (or write) followed by a write (or read) is shown

in Figure 5 and Figure 6.

Parallel Processor Interface (PPI)

(Continued)

dynamic memories. Holding the local bus with the PSC100F

RDY line long enough to violate a DRAM refresh time will re-

sult in lost data within the dynamic memory.

Writing and Reading without the use of RDY : With use of

worst case PSC100F timing, Write and Read cycles can be

successfully completed without the use of the RDY signal. All

read and write cycles will complete within 2.5 SCK cycles

(worst case). Therefore, by assuring at least 2.5 cycles occur

after the rising edge of STB, bus cycles can be completed

without using the RDY “handshake”. The critical timing rela-

tionship within the PSC100F for write and read operation is

between the rising edge of STB and the falling edge of SCK.

The rising edge of strobe latches the address/data and also

generates the internal signals required to complete read/

write within the PSC100F (including a signal with resets the

read/write logic and releases the RDY line). The propagation

of these internal signals is initiated on the first falling edge of

SCK after the STB pin is asserted high. If the rising edge on

STB occurs an internal setup time (t_s4) or greater before the

falling edge of SCK, the bus cycle can be completed within

1.5 SCK cycles (see Figure 4). However, if the internal setup

time is not met, the propagation of internal control/reset sig-

nals is delayed until the next falling edge of SCK (1 SCK

cycle later) which effectively completes the read/write opera-

tion and reset the logic for the next bus cycle within 2.5

cycles (see Figure 5). Synchronizing the rising edge of STB

with the falling edge of SCK to assure that t_s4is met provides

the maximum performance for a read/write operation. How-

ever, the asynchronous interface can be used effectively with

software delays, hardware delays or programmed wait

states (to assure 2.5 SCK cycles are completed) to avoid the

need for synchronization.

SYNCHRONIZATION

Writes and reads can be synchronized by using any of three

methods: polling, interrupts, or wait state generation:

•

Status bits may be polled to see if a register is ready to be

written to or read from. To stabilize the status bits for read

operations, the Update Status bit must be set in MODE2

to latch the status.

Note: The status bits only provide the state of the shifter/buffers and do not

indicate that an internal write or read is complete. Therefore, for appli-

cations not using the RDY signal to monitor the internal write/read sta-

tus, timing must be controlled to assure that at least 2.5 SCK cycles

are completed between consecutive read or consecutive write cycles.

•

Any of three different events can be used to generate in-

terrupts by forcing the INT pin high, see Table 1.

•

The RDY pin can be used to hold off the host until the ad-

dressed register is ready to be accessed. As described

above, this pin can also be used to hold off additional

reads/writes until the synchronizer has recovered from

the previous read/write. RDY

0 signifies that the

’PSC100F is ready to complete the current PPI cycle.

The logic that determines the state of RDY is summa-

rized in Table 2.

Reading from CNT32 can be synchronized for testing by us-

ing the Single Step Counter mode bit.

TABLE 1. Interrupt Logic

MODE1(7) 1 and TDO

MODE1(6) 1 and TDI

MODE1(5) 1 and

Shifter/Buffer Not Full

Shifter/Buffer Not Empty

CNT32 Not Loaded, or at

INT

Terminal Count

Note 6: Interrupts are generated using the INT pin. Three events trigger INT high. Each event has its own mode bit associated with it for masking or enabling these

interrupts.

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Parallel Processor Interface (PPI) (Continued)

TABLE 2. Ready State Logic

Write

Synchronizer

Busy

TDO

TMS0

Shifter/Buffer

Full and

TMS1

Shifter/Buffer

Full and

Read

Synchronizer

Busy

TDI

Shifter/Buffer

Full and

Shifter/Buffer

Empty and

R/W

RDY

A(2:0) 1

A(2:0)

DS100325-12

FIGURE 8. 1149.1 (JTAG) TAP Controller State Diagram

Serial Scan Interface (SSI)

TCK CONTROL

to change only when SCK is low; therefore, TCK always

stops low. TCK does not toggle (remains low) under the fol-

lowing conditions:

TCK CONTROL is the central control block that enables or

disables shift operations and provides byte alignment for the

shifter/buffers. The state of all shifter/buffers and the 32-bit

counter (CNT32) is evaluated here and TCK is stopped and

started. A clock enable circuit allows the “TCK enable” signal

•

TDO Shifter/Buffer is enabled and empty.

TDO Shifter/Buffer is enabled in PRPG mode and is not

fully loaded.

•

TDI Shifter/Buffer is enabled and full.

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asynchronously creating the TCK pulse via an external

PSC100 pin. When the Freeze Pin Enable bit (bit 2 in Mode

will cause TCK to go high. Once the transition is complete,

the Freeze Mode can be removed (i.e. Freeze Pin Enable bit

returned to logic 0 or Freeze pin forced low) and the sampled

data can be shifted out/evaluated using the “standard”

PSC100 protocol. Figure 9 illustrates the logic implementa-

tion of the Freeze feature. It should be noted that Freeze

mode is simply gated with the TCK output and does not dis-

able shift operations within the shifter/buffers or disable

CNT32. Therefore, no shifting or TCK counting using CNT32

should be performed when Freeze mode is enabled.

Serial Scan Interface (SSI) (Continued)

•

TDI Shifter/Buffer is enabled in SSC mode but is not fully

loaded with an initial value.

•

TMS0 Shifter/Buffer is enabled and empty.

TMS1 Shifter/Buffer is enabled and empty.

CNT32 is enabled but not loaded.

CNT32 is enabled and has reached terminal count.

Also included within the TCK control block in CNT3, a 3-bit

count up counter. CNT3 is included to maintain byte align-

ment within the shifter/buffers by providing a signal to toggle

between the two 8-bit FIFOs which comprise the shifter/

buffer. The toggling operation occurs, in an enabled shifter/

buffer, each time CNT3 counts 8 TCK cycles or when CNT32

reaches terminal count. The CNT3 is reset to 0 when CNT32

reaches terminal count or after a PSC100 reset condition.

The “standard” mode of TCK control uses CNT32 in conjunc-

tion with the status registers to start and stop TCK. For this

mode, CNT32 is enabled and loaded with the number of

TCK cycles required to shift the desired bits to/from the scan

chain. The shifter/buffer(s) participating in the shift operation

is enabled and provides the necessary full/empty status to

stop TCK for processor writes/reads. This mode of TCK con-

trol provides a systematic protocol for managing PSC100

operations (specifically, handling partial bytes). Another op-

tion for TCK control relies solely on the status of the shifter/

buffers (i.e., CNT32 is disabled) to start and stop TCK. This

option eliminates the time required to load CNT32, but

makes management of partial bytes (see shifter/buffer de-

scription section) more cumbersome.

FREEZE MODE. This mode is included in the TCK control

block to support the 1149.1 SAMPLE operation. The intent of

the SAMPLE instruction is to allow device input and output

levels to be observed during normal system operation. Data

is latched (or “sampled”) into the boundary scan registers

when the TAP controller (see Figure 8 on previous page)

transitions from the Capture-DR state to the Shift-DR state (if

SAMPLE/ PRELOAD is the active instruction). Synchroniz-

ing this “transition” (rising edge of TCK with TMS at logic low)

with a known system state is imperative to an accurate pass/

fail assessment. The Freeze Mode provides a means of

DS100325-9

FIGURE 9. TCK Logic

DS100325-10

FIGURE 10. TMS Shifter/Buffer Block Diagram

TMS(1:0) SHIFTER/BUFFERS

of shifting is least significant bit first. TMS(1:0) are forced

high upon RST low. TMS(1:0) are TRI-STATEd when OE is

high.

The TMS Shifter/Buffer block diagram is shown in Figure 10.

These two blocks take parallel data and serialize it for shift

operations through the serial port pins TMS0 and TMS1.

Write operations are completed if the shifter/buffer is not full

(independent of whether shifter/buffer is enabled or dis-

abled). Otherwise they are ignored. Shifting occurs when the

following conditions are all true:

Double-buffering is achieved by configuring the shifter/buffer

as a 2 x 8 FIFO. Write and shift operations are controlled by

a local state machine that accepts stimulus from the PPI,

Mode Registers, CNT32 and TCK Control section. The TMS

outputs always change on the falling edge of SCK. The order

•

TMS is enabled with its respective mode bit.

TMS shifter/buffer is not empty.

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with two additional 8-bit parallel-to-serial shift registers. Write

and shift operations are controlled by a local state machine

that accepts stimulus from the PPI, Mode Registers, CNT32,

and the TCK Control section. The TDO output always

changes on the falling edge of SCK. The order of shifting is

least significant bit first. TDO is forced high upon RST low.

TDO is TRI-STATEd when OE is high.

Serial Scan Interface (SSI) (Continued)

•

TCK is enabled according to the logic in TCK Control.

When shift operations are not enabled, the TMS output re-

tains its last state. During long shift sequences, the TMS

shifter/buffer can be disabled and held static so that shift op-

erations are concentrated only on TDI and TDO. The TMS

output also retains its last state when Test Loop-Back opera-

tions are in progress.

Write operations are completed if the shifter/buffer is not full

(independent of whether shifter/buffer is enabled or dis-

abled). Otherwise they are ignored.

Local select circuitry is used to toggle back and forth be-

tween the two registers of the “FIFO” when shifting. At any

given time, one register is selected for shift operations. The

other holds its previous state or can accept new parallel

data. Shift register selection changes due to the following

two events:

Shifting occurs when the following conditions are all true:

•

TDO is enabled with its respective mode bit.

TDO shifter/buffer is not empty.

TCK is enabled according to the logic in TCK Control.

When shift operations are not enabled, the TDO output re-

tains its last state. The TDO output also retains its last state

when Test Loop-Back operations are in progress.

•

CNT3 in TCK Control signals that 8 bits have been

shifted. This event is used for basic toggling between

each of the two shift registers.

Local select circuitry is used to toggle back and forth be-

tween the two registers of the “FIFO” when shifting. At any

given time, one register is selected for shift operations. The

other holds its previous state or can accept new parallel

data. Shift register selection changes due to the following

two events:

•

CNT32 enabled and at terminal count. This event is used

to account for scan lengths which are not multiples of

eight. When shift register selection changes due to this

signal, any data remaining in the shift register is unused.

AUTO TMS HIGH MODE . This feature is included in the

TMS shifter/buffer block to improve the efficiency of the

PSC100 in supporting shift operations within the 1149.1 de-

vices connected to the SSI. Shifting data and instructions

into 1149.1 compliant devices requires that their TAP control-

lers be sequenced to the Shift-DR or Shift-IR states (see Fig-

ure 8). Once in this state, shifting occurs by holding TMS low

and clocking TCK. The last bit is shifted when the TAP con-

troller transitions to the EXIT1 state. This transition requires

a logic 1 on TMS. The Auto TMS High feature, enabled by

setting bit 1 of Mode Register 0, automatically creates a logic

•

CNT3 in TCK Control signals that 8 bits have been

shifted. This event is used for basic toggling between

each of the two shift registers.

•

CNT32 enabled and at terminal count. This event is used

to account for scan lengths which are not multiples of

eight. When shift register selection changes due to this

signal, any data remaining in the shift register is unused.

PRPG MODE . By setting MODE1(4), the TDO Shifter/Buffer

is reconfigured as a 32-bit PRPG (Pseudo Random Pattern

Generator) using the primitive polynomial:

1 on the TMS lines of the PSC100 when CNT32 1. Conse-

quently, the last bit is shifted out without having to load spe-

cific TMS data into the shifter/buffer.

+ X²²+ X²+ X + 1

F(X)

The PSC100 was developed to support both 1149.1 and

non-1149.1 serial test methodologies. Since 1149.1 compli-

ant devices include boundary scan registers on control pins

(i.e. OE), which must remain fixed during boundary scan in-

terconnect testing, generating pseudo-random patterns with

PRPG mode provides limited usefulness for boundary scan

test operations. PRPG mode may provide usefulness in

other serial test or non-test related implementations which

do not require fixed bits in the serial chain.

Note: Auto TMS High mode creates a logic 1 on both TMS lines (i.e., TMS0

and TMS1). Therefore, when using the Auto TMS High feature, all

1149.1 devices connected to the TMS line not participating in the cur-

rent JTAG test operations should be placed in the Test-Logic-Reset

TAP controller state to prevent inadvertent TAP controller transitions.

TDO SHIFTER/BUFFER

The TDO Shifter/Buffer block diagram is shown in Figure 11.

This block takes parallel data and serializes it for shift opera-

tions through the serial port pin TDO. During normal shift

modes, double-buffering is achieved by configuring the

shifter/buffer as a 2 x 8 FIFO. This block can also be config-

ured as a 32-bit Pseudo Random Pattern Generator (PRPG)

Figure 12 shows a block diagram of the Linear Feedback

Shift Register hookup.

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Serial Scan Interface (SSI) (Continued)

DS100325-11

FIGURE 11. TDO Shifter/Buffer Block Diagram Register Hookup

DS100325-14

FIGURE 12. TDO PRPG Block Diagram

The PRPG is loaded by four PPI writes to the TDO address.

When the PRPG enable bit is set, a pulse is issued internally

that initializes the local parallel load logic such that the

PRPG is loaded sequentially, least significant byte first, most

significant byte last. When in PRPG mode, writes can be

completed at any time; however, shift operations will be dis-

abled until the PRPG is fully loaded.

ture can be used for read-only scan operations where data is

shifted into TDI while returning the scan chain to its previous

state when shifting is completed. It can also be used to by-

pass PSC100 devices connected within a boundary scan

chain (i.e., a PSC100 located within a chain, but not provid-

ing the JTAG TAP data). Loop around has limited usefulness

in most boundary scan applications since, typically, data in

the scan chain is shifted out and evaluated as new data is

shifted into the chain for the next test.

LOOP AROUND MODE . This mode, enabled by setting bit

0 in Mode Register 0, will cause data appearing at the TDI in-

put to be placed directly back on the TDO output. This fea-

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•

TDI is enabled with its respective mode bit.

TDI shifter/buffer is not full.

Serial Scan Interface (SSI) (Continued)

WRITING A PARTIAL BYTE TO THE TMS0, TMS1 OR

TDO SHIFTER/BUFFER. Since the TMS0, TMS1 and TDO

shifter/buffers shift out least significant bit first, the valid

(meaningful) bits within a partial byte (i.e., byte containing

TCK is enabled according to the logic in TCK Control.

Local select circuitry is used to toggle back and forth be-

tween the two registers of the “FIFO” when shifting. At any

given time, one register is selected for shift operations. The

other holds its previous state or can accept new serial data.

Shift register selection changes due to the following two

events:

8 valid bits to be shifted to the scan chain) must be stored

and written into the shifter/buffer as the least significant bits.

This will assure that the desired bits will be accurately shifted

to the boundary scan chain. For example, moving the TAP

controllers within the boundary scan chain connected to

TMS0 from the Pause-DR state to the Run-Test/Idle state re-

quires a 3-bit (110) sequence on TMS0. To provide correct

3-bit sequence on TMS0, the partial byte would be written to

the TMS0 shifter/buffer as:

•

CNT3 in TCK Control signals that 8 bits have been

shifted in. This event is used for basic toggling between

each of the two shift registers.

•

CNT32 enabled and at terminal count. This event is used

to account for scan lengths which are not multiples of

eight. When shift register selection changes due to this

MSB

LSB

signal, a partial byte (i.e., byte with eight valid data bits

→

TMS0

shifted from the scan chain) will exist in the correspond-

ing shift register. The embedded test software functions

written to support the evaluation of data read from the

TDI shifter/buffer must consider bit placement when

reading and evaluating a partial byte.

A subsequent enable and load of CNT32 with decimal 3 and

enable of the TMS0 shifter/buffer will initialize the shift opera-

tion. Terminal count on CNT32 will complete the shift opera-

tion. Since terminal count on CNT32 will cause the register

selection to change within the shifter/buffer, the values la-

beled as “x” will not be used and are treated as “don’t cares”.

READING A PARTIAL BYTE FROM THE TDI SHIFTER/

BUFFER. Data is shifted from the scan chain into each TDI

sequently, the valid (i.e., meaningful) bits in a partial byte

shifted into a TDI register will reside in the upper significant

bit locations. For example, if a scan operation involves shift-

ing and evaluating 53 bits returning to TDI, TDI shifter/buffer

must be read 7 times (i.e., 6 full bytes plus a partial byte con-

taining 5 meaningful bits). If the last 5 bits shifted back to the

TDI shifter/buffer are 11010, then upon completion of the

shift operation (i.e., terminal count on CNT32), the shift reg-

ister within the TDI shifter/buffer will contain the following

partial byte:

TDI SHIFTER/BUFFER

The TDI Shifter/Buffer block diagram is shown in Figure 13.

This block shifts in serial data from the TDI port and puts it in

parallel form for read operations at the PPI. During normal

shift modes, double-buffering is achieved by configuring the

shifter/buffer as a 2 x 8 FIFO. This block can also be config-

ured as a 16-bit Serial Signature Compactor (SSC). Write,

read, and shift operations are controlled by a local state ma-

chine that accepts stimulus from the PPI, Mode Registers,

CNT32 and the TCK Control section. The TDI input always

shifts in data on the rising edge of SCK. The order of shifting

is least significant bit first. The TDI input includes a pull-up

resistor to force a logic 1 when the test data signal returning

from the scan chain is floating.

MSB

LSB

→

TDI

Following a read of a partial byte, the embedded test soft-

ware must adjust the position of the valid bits read from the

TDI shifter/buffer or the position of the expected data to as-

sure that an accurate comparison is made (and the

non-meaningful bits are masked).

Read operations are completed if the shifter/buffer is not

empty and SSC mode is not enabled. Otherwise they are ig-

nored. Write operations are only possible while in SSC

mode. Otherwise they are ignored.

Shifting occurs when the following conditions are all true:

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Serial Scan Interface (SSI) (Continued)

DS100325-8

FIGURE 13. TDI Shifter/Buffer Block Diagram

DS100325-13

FIGURE 14. TDI SSC Block Diagram

SSC MODE. By setting MODE1(3), the TDI Shifter/Buffer is

reconfigured as a 16-bit SSC (Serial Signature Compactor)

using the primitive polynomial:

provide masking capabilities and, therefore, provides limited

usefulness for boundary scan test operations. SSC mode

may provide usefulness in other serial test or non-test re-

lated implementations which contain predictable data return-

ing into the TDI shifter/buffer.

+ X¹²+ X³+ X + 1

F(X)

Within a chain of 1149.1 compliant devices, there are typi-

cally one or more input pins which are driven by uncontrolled

signals (i.e., signals which are not driven to known logic lev-

els during a boundary scan CAPTURE operation). These

signals are masked during the evaluation of data returning

from the scan chain. The SSC within the PSC100 does not

Figure 14 shows a block diagram of the Linear Feedback

Shift Register hookup.

The SSC is loaded by two PPI writes to the TDI address.

When the SSC enable bit is set, a pulse is issued internally

that initializes the local parallel load logic such that the SSC

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dress or the CNT32 write control logic will be re-initialized.

This re-initialization will result in a partially filled counter with

an undesired value. CNT32 is reset each time the counter

hits terminal count or by asserting the RST pin. A synchro-

nous reset condition (setting Mode2(1)) does not reset the

counter and a new value must be written to CNT32 to pro-

vide the desired number of TCK cycles.

Serial Scan Interface (SSI) (Continued)

is loaded sequentially, most significant byte first, least signifi-

cant byte last. When in SSC mode, writes can be completed

at any time; however, shift operations will be disabled until

the SSC is fully loaded. PPI reads from TDI are ignored while

in SSC mode.

Upon leaving SSC mode an internal pulse causes the TDI

shifter/buffer to be full. Also, local read select logic is initial-

ized such that the signature is read most-significant byte

first.

SINGLE STEP MODE: All four 8-bit registers are readable

for testability; however, there are no update latches similar to

the ones used for the status bits. To stabilize the counter for

read operations during on-board test, the Single Step Mode

has been added. This allows the user to place CNT32 in any

state and then count for one SCK cycle (TCK will not toggle

when in singled step mode). The result can then be read

from the PPI. The counter can be tested by loading it with

values at its boundary conditions, and then clocking for one

cycle to see the results. For example, the counter could be

loaded with the value:

TEST LOOP-BACK MODES. This feature provides a means

for testing ’PSC100 functionality by looping data appearing

at the output of an outgoing shifter/buffer (i.e., TMS0, TMS1

or TDO) back to the input of the TDI shifter/buffer. The loop

back function is accomplished with a simple multiplexer (see

Figure 13) whose path selection is determined by setting the

mode bits in MODE1(1:0). Loop back does not disable TCK

or prevent shifting of data in the shifter/buffers to the scan

chain(s) connected to the PSC100. Therefore, the state and

operation of the TAP controllers within the scan chain(s)

must be considered when developing Loop-Back test vec-

tors to prevent undesired shifting of data or TAP controller

transitions within the scan chain.

00000001 00000000 00000000 00000000

The next step is to set the Single Step Mode bit so that the

counter counts down to the next state and stops. The next

value is:

00000000 11111111 11111111 11111111

Four read cycles using the PPI will reveal the results of the

test.

32-BIT COUNTER (CNT32)

Note: CNT32 will not wrap from terminal count (i.e., 00000000h decremented

by 1 will remain unchanged and will not wrap to FFFFFFFFh). There-

fore, CNT32 should be loaded with a non-zero value prior to a Single

Step Mode Operation.

CNT32 is a 32-bit, count-down binary counter arranged in

four 8-bit segments. CNT32 can be loaded independent of

its enable/disable status. Loading requires four consecutive

writes to its address (least significant byte first). These four

writes must not be interleaved with writes to any other ad-

TIMING WAVEFORMS

DS100325-15

FIGURE 15. Serial Scan Interface Timing

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Embedded Test Software Support

A SCANPSC100 device driver is provided by National to

supply functions for performing write, read and shift opera-

tions. National also offers a suite of software tools (called

SCAN EASE) which enables ATPG or custom generated test

vectors to be embedded, applied and evaluated within an

IEEE 1149.1 compatible system. SCAN EASE is written to

run on a wide range of processor and memory architectures.

SCAN EASE includes the source code (ANSI C) and is

modular to allow user modification based on application spe-

cific needs.

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Absolute Maximum Ratings (Note 7)

ESD Last Passing Voltage (Min)

4000V

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Recommended Operating

Conditions

Supply Voltage (V_CC

)

−0.5V to +7.0V

Supply Voltage (V_CC

)

DC Input Diode Current (I_IK

)

’PSC100F

4.5V to 5.5V

0V to V_CC

V_I−0.5V

−20 mA

+20 mA

Input Voltage (V_I)

V_IV_CC+ 0.5V

Output Voltage (V_O

)

DC Input Voltage (V_I)

−0.5V to V_CC+0.5V

Operating Temperature (T_A)

Military

DC Output Diode Current (I_OK

)

−55˚C to +125˚C

125 mV/ns

V_O−0.5V

−20 mA

+20 mA

Minimum Input Edge Rate dV/dt

SCAN “F” Series Devices

V_INfrom 0.8V to 2.0V

V_OV_CC+ 0.5V

DC Output Voltage (V_O

)

−0.5V to V_CC+ 0.5V

DC Output Source/Sink Current (I_O

DC V_CCor Ground Current

per Output Pin

)

50 mA

V_CC4.5V, 5.5V

Note 7: Absolute maximum ratings are those values beyond which damage

to the device may occur. The databook specifications should be met, without

exception, to ensure that the system design is reliable over its power supply,

temperature, and output/input loading variables. National does not recom-

mend operation of SCAN outside of recommended operation conditions.

DC Latchup Source or Sink Current

Junction Temperature

Ceramic

300 mA

+175˚C

Storage Temperature

−65˚C to +150˚C

DC Electrical Characteristics

Military

Symbol

Parameter

V_CC

(V)

T_A−55˚C to

Units

Conditions

+125˚C

Guaranteed Limits

V_IH

V_IL

Minimum High

Input Voltage

Maximum Low

Input Voltage

Minimum High

Output Voltage

4.5

5.5

4.5

5.5

4.5

5.5

4.5

5.5

2.0

V_OUT0.1V or

V_CC− 0.1V

0.8

V_OUT0.1V or

0.8

V_CC− 0.1V

I_OUT−50 µA

V_OH

4.4

5.4

V_INV_ILor V_IH

3.70

4.70

I_OH−24 mA

All Outputs Loaded

I_OUT−50 µA

V_OL

Maximum Low

Output Voltage

4.5

5.5

4.5

5.5

0.1

V_INV_ILor V_IH

0.50

I_OL24 mA

All Outputs Loaded

I_IN

Maximum Input

Leakage Current

5.5

1.0

µA

V_INV_CCfor TDI, OE

V_INV_CC, GND for

All Others

I_ILR

Maximum Input

Leakage Current

Minimum

−385

µA

V_INGND for

TDI, OE Only

I_OLD

V_OLD1.65V Max

Dynamic

Maximum Test Duration

2.0 ms, One Output

Loaded at a Time

Output Current

V_OHD3.85V Min

I_OHD

Minimum

Dynamic

5.5

−50

Maximum Test Duration 2.0 ms,

Output Current

One Output Loaded at a Time

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DC Electrical Characteristics (Continued)

Military

Symbol

I_OZ

Parameter

V_CC

(V)

T_A−55˚C to

Units

µA

Conditions

+125˚C

Guaranteed Limits

Maximum

10.0

11.0

V_INV_CC, GND

V_IN(OE , R/W , CE , STB)

V_IL, V_IH

TRI-STATE

Leakage Current

Maximum I/O

Leakage Current

I_OZT

µA

V_INV_CC, GND

V_OV_CC, GND

_IN(R/W , CE , STB) V_IL, V_IH

I_CC

Maximum

Quiescent

5.5

160

920

1.60

µA

TDI, OE Float

Supply Current

I_CCmax

Maximum

Quiescent

TDI, OE low

Supply Current

Maximum

I_CCT

V_INV_CC− 2.1V

_CC/Input

Maximum

_CC/Input

Float: TDI, OE

I_CCTR

V_INV_CC−2.1V

5.5

1.65

TDI and OE Only

Float Untested Pin

Note 8: This parameter is not directly testable, but is derived for use in Total Power Supply calculations.

AC Electrical Characteristics/Operating Requirements

Symbol

Parameter

V_CC

Military

Units

Fig.

No.

(V)

T_A−55˚C to +125˚C

(Note 9)

C_L50 pF

Min

5.5

6.5

7.0

7.5

9.0

10.0

2.0

1.5

Max

19.5

21.0

24.0

39.0

34.0

36.0

13.0

10.0

16.5

PARALLEL PROCESSOR INTERFACE (PPI)

t_pd1

Prop Delay

R/W to RDY

Prop Delay

A to RDY

5.0

2, 3, 4

2, 3

t_pd2

t_pd3

Prop Delay

A to D

t_pd4

Prop Delay

STB to RDY

Prop Delay

SCK to D

2–4, 6

2, 3

t _pd10

t _pd11

t _pd12

t_en1

Prop Delay

SCK to INT

Prop Delay

SCK to RDY

Enable Time

CE to RDY

Disable Time

CE to RDY

Enable Time

CE to D

t_dis1

2, 3

t_en2

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AC Electrical Characteristics/Operating Requirements (Continued)

Symbol

Parameter

V_CC

(V)

Military

T_A−55˚C to +125˚C

Units

Fig.

No.

(Note 9)

C_L50 pF

Min

2.5

3.0

2.5

0.5

1.0

4.5

5.0

4.5

0.0

1.0

0.5

7.5

Max

14.5

17.5

16.0

14.5

PARALLEL PROCESSOR INTERFACE (PPI)

t_dis2

t_en3

t_dis3

t_en

t_dis

t_h1

t_s1

t_h2

t_s2

t_h3

t_s3

t_h

Disable Time

CE to D

5.0

Enable Time

R/W to D

Disable Time

R/W to D

Enable Time

STB to D

Disable Time

STB to D

Hold Time,

R/W to STB

Setup Time

R/W to STB

Hold Time,

2–4, 6

2, 3

A to STB

↑

Setup Time,

A to STB

↑

Hold Time,

D to STB

↑

Setup Time,

D to STB

↑

Hold Time,

CE to STB

Setup Time,

CE to STB

Setup Time,

2–4, 6

4–7

t_s

t_s4

STB to

↑

SCK ↓

t_h4

Hold Time,

5.0

0.0

4–7

STB to

↑

SCK ↓

t_h

Hold Time,

STB to RDY

5.0

0.0

t_W

Clock Pulse

Width, SCK, H

or L

20.0

4, 6

t_W1

Pulse Width

STB (H or L)

Maximum

5.0

6.0

f_max

MHz

Frequency

Clock

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AC Electrical Characteristics/Operating Requirements (Continued)

Symbol

Parameter

V_CC

(V)

Military

T_A−55˚C to +125˚C

Units

Fig.

No.

(Note 9)

C_L50 pF

Min

3.0

5.5

4.5

3.0

1.5

2.0

1.5

0.5

Max

14.0

19.5

18.5

13.5

10.0

13.0

11.0

SERIAL SCAN INTERFACE (SSI)

t_pd5

t_pd6

t_pd7

t_pd8

t_pd9

t_en4

t_dis4

t_h5

Prop Delay

SCK to TCK

Prop Delay

SCK to TDO

Prop Delay

SCK to TMS

Prop Delay

FRZ to TCK

Prop Delay

TDI to TDO

Enable Time

OE to JTAG

Disable Time

OE to JTAG

5.0

Setup Time, H

or L, TDI to

SDK (Note

10)

t_s5

Hold Time, H

or L, TDI to

SDK (Note

10)

5.0

7.5

RST RELATED TIMING

t_pd

Prop Delay

5.0

8.0

7.0

5.5

6.5

1.0

29.5

31.0

28.0

21.0

20.0

RST to D

t_pd

Prop Delay

RST to RDY

Prop Delay

RST to INT

Prop Delay

RST to TDO

Prop Delay

RST to TMS

Pulse Width

RST (L)

t_phl

t_plh

t_WR

t_REC

Recovery

Time

SCK from

RST

Note 9: Voltage Range 5.0 is 5.0V 0.5V.

Note 10: SSC Mode

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SHIFT-ENABLE signal which is generated internal to the

’PSC100, based on the status of the TDI buffer and the

Mode Registers.

Application Note

SCK MINIMUM PULSE WIDTH CALCULATION

We now see the three major timing components which limit

the duration of the SCK pulse width low. There are two minor

additional delays which should be noted. The TCK signal

from the ’PSC100 needs to arrive at the target device to be

recognized, and this takes a finite amount of time depending

on the signal trace length and impedance. Similarly, the TDO

signal of the last target in the chain needs to reach the TDI

pin of the ’PSC100, taking a finite amount of time as well.

These two trace delays can be minimized by making the tar-

get device closest to the ’PSC100 the last device in the

chain. See Figure 17.

The SCANPSC100 Parallel to Serial Converter is intended

to act as the interface between a processor and an IEEE

1149.1 boundary scan chain. When used in this configura-

tion, there is a critical timing situation that is not obvious.

This timing involves the system clock rate at which data from

the scan ring is being read into the ’PSC100’s TDI pin (target

TAP controllers in SHIFT-DR or SHIFT-IR states).

To fully understand the events which are taking place during

this critical period, it is useful to view the waveforms of inter-

est as they relate in time. See Figure 16. The TCK is derived

internally to the ’PSC100 based on the system clock (SCK)

and clock gating control. The result is that when TCK is run-

ning, it is at the same frequency as SCK but delayed in time

by the SCK-TCK propagation delay.

PROGRAMMING RESTRICTIONS

Because certain mode bits enable shift operations for certain

functions, these mode bits should not be changed when shift

operations are in progress. The alignment of all registers

during shift operations is controlled by a three bit counter in

the TCK control block. Enabling or disabling a function in the

middle of a shift operation may disrupt the logic necessary to

keep all shifter/buffers byte-aligned. For example, if the TDO

shifter/buffer (already loaded) is enabled while the three bit

counter value is three, the shifter/buffer will only shift out 5

bits of the first byte loaded.

The TCK signal from the ’PSC100 drives all of the IEEE

1149.1 target devices. On the rising edge of TCK, data

present at each scan cell is clocked into it. On the falling

edge, this data is presented at the output of the same scan

cell for the next adjacent cell to read. With regards to the last

cell in a particular target, the falling edge of TCK presents

the data in the last scan cell to the TDO pin, a TCK-TDO

propagation delay later.

At the ’PSC100, data shifted in through the TDI pin is

clocked in on the rising edge of SCK, not TCK. The reason

for this is that TCK is generated internal to the ’PSC100 and

intended to control the boundary scan targets. The ’PSC100

is controlled by SCK, therefore the signal to be shifted into

the TDI pin needs to be referenced to SCK not TCK. New

TDI data must be present a TDI-SCK set-up time prior to the

rising edge of SCK in order to guarantee validity. Although

SCK is usually continuous, the TDI buffer is controlled by a

The following bits should not be changed when shift opera-

tions are in progress, i.e., when TCK is enabled (see TCK

control section):

•

MODE0(7:3)

MODE1(4:3)

MODE2(0)

DS100325-16

Pw(L) minimum Tpd1 + Td1 + Tpd2 + Td2 + Tsu

FIGURE 16. System Clock Timing for Accurate TDI Data

www.national.com

Application Note (Continued)

DS100325-17

Note:- - - - - Minimize the lengths of these two traces.

FIGURE 17. SCANPSC100 Location Relative to Targets

www.national.com

Physical Dimensions inches (millimeters) unless otherwise noted

28-Pin Leadless Chip Carrier (LCC)

NS Package Number E28A

28-Pin Ceramic DIP

NS Package Number J28A

28-Lead Cerpack

NS Package Number WA28D

www.national.com

Notes

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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT

DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL

COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or

systems which, (a) are intended for surgical implant

into the body, or (b) support or sustain life, and

whose failure to perform when properly used in

accordance with instructions for use provided in the

labeling, can be reasonably expected to result in a

significant injury to the user.

2. A critical component is any component of a life

support device or system whose failure to perform

can be reasonably expected to cause the failure of

the life support device or system, or to affect its

safety or effectiveness.

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Tel: 1-800-272-9959

Fax: 1-800-737-7018

Email: support@nsc.com

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National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

1 of 4

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Products > Military/Aerospace > Logic > SCAN > SCANPSC100F

Product Folder

SCANPSC100F

Embedded Boundary Scan Controller

Generic P/N 100F

Contents

General Description

Features

Datasheet

Package Availability, Models, Samples

& Pricing

Application Notes

General Description

The SCANPSC100F is designed to interface a generic parallel processor bus to a serial scan

test bus. It is useful in improving scan throughput when applying serial vectors to system test

circuitry and reduces the software overhead that is associated with applying serial patterns

with a parallel processor. The 'PSC100F operates by serializing data from the parallel bus for

shifting through the chain of 1149.1 compliant components (i.e., scan chain). Scan data

returning from the scan chain is placed on the parallel port to be read by the host processor.

Up to two scan chains can be directly controlled with the 'PSC100F via two independent

TMS pins. Scan control is supplied with user specific patterns which makes the 'PSC100F

protocol-independent. Overflow and underflow conditions are prevented by stopping the test

2 of 4

clock. A 32-bit counter is used to program the number of TCK cycles required to complete a

scan operation within the boundary scan chain or to complete a 'PSC100F Built-In Self Test

(BIST) operation. SCANPSC100F device drivers and 1149.1 embedded test application code

are available with National's SCANEase software tools.

Features

Compatible with IEEE Std. 1149.1 (JTAG) Test Access Port and Boundary Scan

Architecture

Supported by National's SCAN Ease (Embedded Application Software Enabler)

Software

Uses generic, asynchronous processor interface; compatible with a wide range of

processors and PCLK frequencies

Directly supports up to two 1149.1 scan chains

16-bit Serial Signature Compaction (SSC) at the Test Data In (TDI) port

Automatically produces pseudo-random patterns at the Test Data Out (TDO) port

Fabricated on FACT™ 1.5 µm CMOS process

Supports 1149.1 test clock (TCK) frequencies up to 25 MHz

TTL-compatible inputs; full-swing CMOS outputs with 24 mA source/sink capability

Standard Microcircuit Drawing (SMD) 5962-9475001

Datasheet

Size

(in

Kbytes)

Title

Date

Receive via

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Online

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SCANPSC100F Embedded Boundary Scan Controller(IEEE 1149.1

Support)

16-Sep-

364 Kbytes

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3 of 4

Package Availability, Models, Samples & Pricing

Samples

Package

Budgetary Pricing

BSDL

Model

File

Std

Pack

Size

Package

Marking

Part Number

Status

$US

Quantity

Electronic

Orders

Type

pins

each

tube

N/A

[logo]¢Z¢S¢4¢A$E

SCANSTA101

SCANSTA101ME

SSOP

Preliminary

N/A

[logo]¢Z¢S¢4¢A

SCANPSC

100FLMQB/Q

$E 5962-

tray

Full

production

5962-9475001Q3A

LCC

250+ $38.5000 of

9475001Q3A

tube

[logo] ¢Z¢S¢4¢A$E

Full

production

5962-9475001QXA

SCANPSC100FMW

Cerdip

N/A

250+ $30.5000 of SCANPSC100FDMQB /Q

5962-9475001QXA

SOIC

WIDE

[logo]¢Z¢S¢4¢A$E

SCANPSC100FMW

Preliminary

N/A

[logo] ¢Z¢S¢4¢A$E

SCANPSC100FFMQB

5962-9475001QYA

tube

Full

production

5962-9475001QYA

Cerpack

Cerquad

N/A

250+ $32.9000 of

tube

N/A

[logo]¢Z¢S¢4¢A$E

SCANSTA101W-

QML

SCANSTA101W-

QML

Preliminary

Application Notes

4 of 4

Size

(in Kbytes)

Title

Date

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View Online

Please use Adobe Acrobat to view PDF file(s).

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[Information as of 2-Sep-2000]

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SCANPSC100FMW [TI]

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