TEST FEATURES
15-15
15
15.3.6.1
Example
In the example that follows, two command actions are described. The example starts in the reset
state, a new instruction is loaded and executed. See
Figure 15-3
for a JTAG example. The steps
are:
1.
Load the
sample
/
preload
instruction into the Instruction Register:
1.1. Select the Instruction register scan.
1.2. Use the Shift-IR state four times to read the least through most significant instruction
bits into the instruction register (we do not care that the old instruction is being shifted
out of the TDO pin).
1.3. Enter the Update-IR state to make the instruction take effect.
1.4. Exit the Instruction register.
2.
Capture and shift the data onto the TDO pin:
2.1. Select the Data register scan state.
2.2. Capture the pin information into the n-stage Boundary-Scan register.
2.3. Enter and stay in the shift-DR state for n times while recording the TDO values as the
inputs sampled. As the data sampled were shifting in the TDI was being read into the
Boundary-Scan register. This could later be written the output pins.
2.4. Pass through the Exit1-DR and Update-DR to continue.
This example does not make use of the pause states. Those states would be more useful where we do
not control the clock directly. The pause states let the clock tick without affecting the shift registers.
The old instruction was abcd in the example. It is known that the original value will be the ID code
since the example starts from the reset state. Other times it will represent the previous opcode. The
new instruction opcode is 0001
2
(
sample
/
preload
). All pins are captured into the serial
Boundary-Scan register and the values are output to the TDO pin.
The clock signal drawn at the top of the diagram is drawn as a stable symmetrical clock. This is not
in practice the most common case. Instead the clocking is usually done by a program writing to a
port bit. The TMS and TDI signals are written by software and then the software makes the clock
go high. The software typically will often lower the clock input quickly. The program can then
read the TDO pin.
Содержание i960 Jx
Страница 1: ...Release Date December 1997 Order Number 272483 002 i960 Jx Microprocessor Developer s Manual ...
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Страница 25: ...1 INTRODUCTION ...
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Страница 35: ...2 DATA TYPES AND MEMORY ADDRESSING MODES ...
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Страница 47: ...3 PROGRAMMING ENVIRONMENT ...
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Страница 73: ...4 CACHE AND ON CHIP DATA RAM ...
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Страница 85: ...5 INSTRUCTION SET OVERVIEW ...
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Страница 111: ...6 INSTRUCTION SET REFERENCE ...
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Страница 195: ...INSTRUCTION SET REFERENCE 6 83 6 Opcode mov 5CCH REG movl 5DCH REG movt 5ECH REG movq 5FCH REG See Also LOAD STORE lda ...
Страница 233: ...7 PROCEDURE CALLS ...
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Страница 257: ...8 FAULTS ...
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Страница 291: ...9 TRACING AND DEBUGGING ...
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Страница 309: ...10 TIMERS ...
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Страница 325: ...11 INTERRUPTS ...
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Страница 369: ...12 INITIALIZATION AND SYSTEM REQUIREMENTS ...
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Страница 413: ...13 MEMORY CONFIGURATION ...
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Страница 429: ...14 EXTERNAL BUS ...
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Страница 469: ...15 TEST FEATURES ...
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Страница 493: ...A CONSIDERATIONS FOR WRITING PORTABLE CODE ...
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Страница 503: ...B OPCODES AND EXECUTION TIMES ...
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Страница 515: ...C MACHINE LEVEL INSTRUCTION FORMATS ...
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Страница 523: ...D REGISTER AND DATA STRUCTURES ...
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Страница 551: ...GLOSSARY ...
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Страница 561: ...INDEX ...
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