https://github.com/rouming/avr-gdbserver

Embedded GDB server implementation for 8-bit AVR MCU
https://github.com/rouming/avr-gdbserver

Last synced: 5 days ago
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Embedded GDB server implementation for 8-bit AVR MCU

• Host: GitHub
• URL: https://github.com/rouming/avr-gdbserver
• Owner: rouming
• Created: 2012-10-05T12:38:37.000Z (about 12 years ago)
• Default Branch: master
• Last Pushed: 2021-05-17T16:22:11.000Z (over 3 years ago)
• Last Synced: 2024-04-22T00:29:08.923Z (7 months ago)
• Language: C
• Homepage:
• Size: 65.4 KB
• Stars: 19
• Watchers: 6
• Forks: 7
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
Embedded GDB server for AVR MCU

===============================

Embedded GDB server implementation for 8-bit AVR MCU for debugging

thru UART.

![UART debugging](image.png)

### Usage:

GDB server on the running AVR MCU can be accessed using UART:

    $ avr-gdb gdb.elf

    GNU gdb (GDB) 7.4

    (gdb) set remotebaud 9600

    (gdb) target remote /dev/ttyUSB0`

Full usage example can be seen here: https://youtu.be/36OgekfiLLc

### How it works:

The operational principle is simple: UART RX is parsed by gdb.c and GDB

commands are expected on the wire.  When breakpoint is sent from GDB client,

code is modified on that address, EEPROM is updated and original instruction

is replaced with a trap opcode, which actually is RJMP on iself to make

program spin on that address.  Meanwhile each second timer interrupt happens

and checks where MCU was interrupted, if interruption address is equal to

one of the breakpoints - gdb.c sends to the GDB client special GDB_SIGTRAP

state using UART TX, which indicates that breakpoint was hit.

### Disclaimer:

Code is just an experiment and written for fun, so I did not do any attempts

to make it architecture independent.  Also because this is completely software

implemention without any HW support I fully utilize UART and one timer interrupt.

And yes a lot of code which occupies quite a lot EEPROM.  What a bummer.

### Author

Roman Pen