I'm letting folks know that I'm currently working on implementing ARM Assembly level instruction debugger support via GDB. This is a software-only debugger (i.e., no need for a JTAG interface) that I plan to release under the GPL. The project is currently at the preliminary phase.
My rationale for doing so is because I'll be using the NXT to teach assembly language programming for ARM processors to CS majors, where the JTAG requirement would be too expensive as well as inconvenient.
Credit for the original concept goes to nxtgcc (Rasmus Pedersen). Currently I'm developing it for the NxOS code base, though I'm keen to get it into the {enhanced, nxt-improved, nxtgcc} LEGO NXT firmware so that there would be a wider audience.
The way the ARM debugger works is as follows:
Code: Select all
[GDB for ARM target] <--TCP/IP--> [GDB Server] <--- USB / Bluetooth? ---> [NXT]
Compiler: GCC based Assembler / C Compiler
Connection: USB (though Bluetooth may be possible in future)
The project will involve developing the following modules:
- - NXT ARM Breakpoint instruction exception handler (done)
- NXT ARM Remote Debugger Stub (preliminary work started, need to coordinate with GDB Server message protocol specification)
- NXT USB Stack (specification stage -- I'd welcome suggestions on the best approach, esp. wrt. portability / reusability between NxOS and NXT firmware, and also which USB Profile is most suitable)
- GDB Server with USB support (need design & Debug Message protocol specification, no code yet)
