Microcontroller Register Viewer for GDB

Since a long time I have been using GDB + a GDB server of choice to debug many embedded targets. GDB's command line interface is powerfull and serves me really well, except for one pain:

Reading peripheral registers.

I know there's efforts like EmbSysRegView and GNU ARM Eclipse, but I really don't want to use Eclipse as a GUI for developing nor debugging. My preferred combo is Vim/Make/GCC/GDB/OpenOCD/...

So I decided to fix this in a really simple way: You load an extra .elf file containing the symbols for all the registers. This will effectively give you access to your microcontroller's peripheral registers, e.g. like this:

(gdb) p/x USART6->SR
$1 = 0xc0
(gdb) p/x USART6
$2 = {SR = 0xc0, DR = 0x0, BRR = 0x2d9, CR1 = 0x202c, CR2 = 0x0, CR3 = 0x0, GTPR = 0x0}

1. Clone or download repo
2. cd /path/to/ucregview
3. make TARGET=name_of_supported_target

1. Fire up GDB, connect to remote target as usual
2. In addition to your application's .ELF file, load the ucregview_xxx.elf symbols, too:

• (gdb) add-symbol-file ucregview_xxx.elf 0x0

3. Read any memory-mapped peripheral register

• (gdb) p/x USART1->CR1

4. Write to peripheral registers from GDB

• (gdb) set USART6->CR1 = 0xE8
• (gdb) p/x USART6->CR1
• $3 = 0xe8

For now, only a few microcontrollers are supported, feel free to add more and file a pull request!

• STM32L051xx
• STM32F407xx