picdb

=====

Python-based command-line debugger for Microchip PIC processors.

Debugger written in Python, and requires jython for execution. Interacts with the Java mdbcore API provided by Microchip in the MPLAB X installation. This is the same API used by Microchip's currently incomplete "mdb.sh", and MPLAB X itself.

For now this is an early demonstration, working only with the PICkit3 and tested only with the PIC32MX150F128B processor.

I wrote this because mdb.sh is currently incomplete, and nearly unusable, so loading or debugging PIC code at the command-line was impossible.

Running

=====

1. Verify path to JARs is correct in picdb.sh
2. run picdb.sh.

Supported features

=====

• Basic debugger commands
  • connect (connect to debugger and target device)
  • load (load ELF file onto target)
  • break (add breakpoints)
  • breakpoints (list breakpoints)
  • continue (run target)
  • step (step target -- currently StepOver only)
  • print (print information about something -- currently only Program Counter)
  • help (list possible commands, or display specific command's help)
  • debug (drop to a Python debugger, so you can debug while you debug.)
  • quit
• Readline input handling supports up/down keys, and history.
• Address-to-Source-Line conversions when stepping.
• Partial assembly code output when stepping.

TODO

=====

Basic functionality:

• Display source code
• View memory
• View disassembly
• View global and local symbols
• View registers
• Delete/modify/disable breakpoints
• Advanced breakpoints (conditional, watchpoints)

More advanced:

• Recover nicely from losing the debugger/target
• Command line arguments
• Scripting

Example session

=====

$ picdb.sh 
PICdb> connect PIC32MX150F128B    
content/mplab/mplab.deviceSupport
content/mplab/MPHeader.xml
content/mplab/PluginBoardSupport.xml
Connecting to PICkit3...
Nov 8, 2012 4:09:08 PM com.microchip.mplab.mdbcore.RealICETool.RIMessages OutputMessage
INFO: 

PICdb> load test.elf
Loading ELF file...
Resetting target...
PC: 0xBFC00000
PICdb> break 0x9D00B8C8
New breakpoint at 0x9D00B8C8 (MainDemo.c:431)
PICdb> break 0x9D00B982
New breakpoint at 0x9D00B982 (MainDemo.c:534)
PICdb> breakpoints
All breakpoints:
0: 0x9D00B8C8 (MainDemo.c:431) *
1: 0x9D00B982 (MainDemo.c:534) *
PICdb> continue
Breakpoint 1: Stopped at 0x9D00B982 (MainDemo.c:534)
PICdb> step
PC: 0x9D00B982  (MainDemo.c:534)  (LW V0, -32416(S0))
PICdb> print $pc
PC: 0x9D00B9AC
PICdb> continue
Breakpoint 0: Stopped at 0x9D00B8C8 (MainDemo.c:431)
PICdb> 
PICdb> help
Type 'help <topic>' for help.

print               
continue            
step                Step over next source line.
break               
connect             Conects to a PIC target.
breakpoints         
help                Displays this help.
quit                Quits this program.
load                Load ELF file onto target.

PICdb> help connect

Connects to a PIC target.
Usage: connect <PIC device>
ex: connect PIC32MX150F128B

PICdb>   

Reverse engineering notes

=====

Get public methods from classes in a jar: $ i=debugger; javap -classpath com-microchip-mplab-open-hid.jar -s $(jar -tf com-microchip-mplab-open-hid.jar |grep class |sed 's/.class//g') |less

Save all public methods into text files: $ for i in ls *.jar;do echo $i; javap -classpath $i -s $(jar -tf $i |grep class |sed 's/.class//g') > ~/pic_classes/$i.txt; done

Microchip's terrible command-line interface: $ /Applications/microchip/mplabx/mplab_ide.app/Contents/Resources/mplab_ide/bin/mdb.sh

Edit mdb.sh to launch with: $jvm -javaagent:/Users/trevor/Downloads/intrace-agent.jar ...

Trace java method calls with InTrace.app

Examples and some documentation available in PIC SDK. Must register here: http://www.opensource4pic.org/