How to debug two or more microcontrollers with JTAG chaining? - debugging

Question

I managed to program and debug an STM32F4 Microcontroller, did some simple operations and wrote small scripts.
The setup
Microcontroller : STM32F405RG
Debug probe: I am using an old JTAGKEY2 by Amontec
Toolchain : openOCD & GDB on port 3333
I am not using any GUI and any specific soft tool.
The goal
Now I'd like to level up a little bit.
My project consists of 3 MCUs on a PCB working in redundancy.
I would like to debug Two or more STM32F4 and do some operations in one MCU while the others are halted. Here is an example :
Program all the devices (let's call them MCU1 & MCU2 ) with the same .elf .
Run.
Halt MCU1 & MCU2 at a specific timing ( like 10sec after running ).
Modify r4 of MCU1 only
Resume all targets.
For one MCU, I call the target config file smt32f4x.cfg.
For two MCUs, I read OpenOCD User's Guide and it seems that I have to create a new tap.
But first, I wanted to try to debug both MCU1 & MCU2 with the same config.
I wired the system in order to chain the MCUs on the bus, opened a terminal and typed openocd in my project folder.
The Issue
As expected I get this message:
Info : JTAG tap: STM32F405RGTx.bs tap/device found: 0x06413041 (mfg: 0x020 (STMicroelectronics), part: 0x6413, ver: 0x0)
Info : JTAG tap: auto0.tap tap/device found: 0x4ba00477 (mfg: 0x23b (ARM Ltd.), part: 0xba00, ver: 0x4)
Info : JTAG tap: auto1.tap tap/device found: 0x06413041 (mfg: 0x020 (STMicroelectronics), part: 0x6413, ver: 0x0)
Warn : AUTO auto0.tap - use "jtag newtap auto0 tap -irlen 4 -expected-id 0x4ba00477"
Warn : AUTO auto1.tap - use "jtag newtap auto1 tap -irlen 5 -expected-id 0x06413041"
Info : STM32F405RGTx.cpu: hardware has 6 breakpoints, 4 watchpoints
adapter speed: 2000 kHz
Info : JTAG tap: STM32F405RGTx.cpu tap/device found: 0x4ba00477 (mfg: 0x23b (ARM Ltd.), part: 0xba00, ver: 0x4)
Info : JTAG tap: STM32F405RGTx.bs tap/device found: 0x06413041 (mfg: 0x020 (STMicroelectronics), part: 0x6413, ver: 0x0)
Info : JTAG tap: auto0.tap tap/device found: 0x4ba00477 (mfg: 0x23b (ARM Ltd.), part: 0xba00, ver: 0x4)
Info : JTAG tap: auto1.tap tap/device found: 0x06413041 (mfg: 0x020 (STMicroelectronics), part: 0x6413, ver: 0x0)
target halted due to debug-request, current mode: Thread
xPSR: 0x01000000 pc: 0x08000910 msp: 0x20020000
What happens then is that only one MCU is programmed.
So I think I might create a board config file and use
jtag newtap auto0 tap -irlen 4 -expected-id 0x4ba00477
and use one DAP per TAP ...
As I'm not confident with my skills I didn't manage to start my own config file from scratch.
And I didn't find config examples with several microcontrollers nor examples in gdb to give debug commands to different commands to different MCU on the bus.
The Questions
Where can I find Board config examples with several MCU?
Is it possible to give debug commands to only one of the devices under debug? How?

Answer 1

I did it using serial numbers of multiple st-links.
#To invoke without this script: openocd -s /share/openocd/scripts -f interface/stlink-v2-1.cfg -f target/stm32f1x.cfg
gdb_port 3334
tcl_port 6667
telnet_port 4445
#To run: openocd -s /share/openocd/scripts and then telnet localhost 4445
#To erase type into telnet: flash erase_sector 0 0 127
#To read device ID and Flash size type into telnet: flash probe 0
source [find interface/stlink-v2-1.cfg]
hla_serial \x56\x3F\x6E\x06\x66\x3F\x48\x55\x38\x57\x09\x67
transport select hla_swd
source stm32f1x-nores.cfg
reset_config none srst_nogate
Look at the hla_serial line. Each MCU has it's own st-link connected over SWD and each st-link has own oocd configuration with serial number and own port. Then launch oocd for each one and you will get GDB server per each MCU.
You can get serial number of st-link using lsusb -v command on Linux. Some clones do not have serial number and some need to be upgraded. Google will help you.

Answer 2

I was able to figure out how to program two micro controller using Openocd
I am currently using USB Bus Blaster V4 Dev Board which contains FT2232 USB to JTAG Converter IC.
My Setup consist of 2 STM32 MCU in daisy Chain configuration.
Since both the MCU have same tap IC i made board config file as suggested by the user guide on page number 22 section 6.2.1 as follows:
set CHIPNAME stm32master
source [find target/stm32f4x.cfg]
-# Chip #2: STM32F405 for Slave STM32, little endian
set CHIPNAME stm32slave
source [find target/stm32f4x.cfg]
gdb_memory_map disable
reset_config srst_only```
The command used for starting openocd is as follows:
sudo openocd -d2 -f interface/ftdi/dp_busblaster_kt-link.cfg -f board/stm32trail.cfg -c init -c scan_chain -c targets
My output after executing the above command in terminal is as follows:
The sequence in which I executed commands in telnet local host are as follows:
targets stm32master.cpu
halt
targets stm32slave.cpu
halt
flash erase_sector 0 0 7
flash write_image erase /home/nikhil/Downloads/Red_Led_C13.hex
verify_image /home/nikhil/Downloads/Red_Led_C13.hex
reset
targets stm32master.cpu
halt
flash erase_sector 0 0 7
flash write_image erase /home/nikhil/Downloads/Red_Led_C13.hex
verify_image /home/nikhil/Downloads/Red_Led_C13.hex
reset
I was able to program both MCU successfully .