JTAG
From DP
NOTE: As of v5.9 the JTAG terminal library was moved to the Bus Pirate bonus/extras firmware.
Bus Pirate firmware v5+ (main firmware) includes support for the OpenOCD JTAG debugger instead, this is a much better option.
Contents |
Overview
- Bus: JTAG (Joint Test Action Group).
- Connections: 4 connections (TDI, TCK, TDO, TMS) and ground.
- Output type: 3.3volt normal, or open collector (pull-up resistors required).
- Pull-up resistors: required for open collector output mode (2K – 10K).
- Maximum voltage: 5.5volts (5volt safe).
- Last documentation update: v5.6.
JTAG is actually a protocol over SPI. This library performs common JTAG functions and manages the JTAG state machine. Read more about JTAG mode here.
Configuration options
Output type - open drain/open collector (high=Hi-Z, low=ground) , normal (high=3.3volts, low=ground). Use open drain/open collector output types with pull-up resistors for multi-voltage interfacing.
Syntax
| A/a/@ | Toggle auxiliary pin. Capital “A” sets AUX high, small “a” sets to ground. @ sets aux to input (high impedance mode) and reads the pin value. |
| D/d | Measure voltage on the ADC pin (v1+ hardware only). |
| W/w | Capital ‘W’ enables the on-board power supplies. Small ‘w’ disables them. (v1+ hardware only). |
| [ | Move JTAG state machine (SM) to INSTRUCTION register. Last bit of byte writes is delayed until leaving the INSTRUCTION register. |
| { | Move JTAG SM to DATA register. |
| ] or } | Move JTAG SM to IDLE register. |
| r | Read one byte. (r:1…255 for bulk reads) |
| 0b | Write this binary value. Format is 0b00000000 for a byte, but partial bytes are also fine: 0b1001. |
| 0x | Write this HEX value. Format is 0×01. Partial bytes are fine: 0xA. A-F can be lower-case or capital letters. |
| 0-255 | Write this decimal value. Any number not preceded by 0x or 0b is interpreted as a decimal value. |
| , | Value delimiter. Use a coma or space to separate numbers. Any combination is fine, no delimiter is required between non-number values: {0xa6,0, 0 16 5 0b111 0haF}. |
| & | Delay 1uS. (&:1…255 for multiple delays) |
| (#) | Run macro, (0) for macro list |
| Bitwise | |
| ^ | Send one clock tick. (^:1…255 for multiple clock ticks) |
| / or \ | Toggle clock level high (/) and low (\). Includes clock delay (100uS). |
| - or _ | Toggle data state high (-) and low (_). Includes data setup delay (20uS). |
| ! | Read one bit with clock. |
| . | Read data pin state (no clock). |
| 0 | Macro menu |
| 1 | Reset chain |
| 2 | Probe chain |
| 3 | XSVF player. JTAG programmer. (deprecated) |