STM32L1-Discovery arm-none-eabi- toolchain template for asm

This is a template for using the STM32L1-Discovery with the GNU ARM toolchain. This template assumes you are writing just assembly code. You can either build it yourself or use a pre-compiled version from somewhere such as launchpad.net

This template is based around the first lab released for COMS20001.

Note: You'll now have to use GNU ASM directives rather than the ones shown in the original coursework. I've converted all of the ones in the current template for now but if you need to change later coursework directives they're all pretty similair and a bit of googling will give you the correct one to use.

If you'd like to use this code outside of the COMS20001 course you can simply change the jump instruction in System_Init.s to something other than Lab_Start in Init_End:

You can further modularise this by removing the jump from System_Init.s and uncommenting the application jump in startup_stm32l1xx_md.s to jump to your own application's code.

This template modifies various pieces of other templates:

• ld/stm32.ld
• startup_stm32l1xx_md.s

and rewrites the provided System_Init.s and Lab1-Task1.s provided by Simon to use GNU ASM directives.

Compile your code

To simply compile your code first make sure all your sourcefiles are referenced in the Makefile SRCS variable.

You can then just run make program to compile your code into both a ELF binary (can be loaded into gdb) and a bin (for writing straight to flash memory).

Flash your code

This project uses the stlink project to interface with microcontroller however you could also use something such as OpenOCD.

You can install the stlink project at https://github.com/texane/stlink or if you're using OS X brew has the package available.

Use make flash to compile the sources specified in the Makefile and write them to device's flash memory.

Debugging

By default the project is always compiled with the debug parameter -g. The Makefile also provides a target to use the arm-none-eabi-gdb for remote debugging.

You can run this using make debug will compile your code, then load it into gdb.

You can then run continue in the gdb console to start running the code.

Note: This requires you to already be running the stlink project and connected to the device by first runnnig the command st-util.

Notes

When using BX BLX or any other instructions that have the potential to switch from ARM mode to thumb mode, ensure you preface the label with .thumb_func. This is due to the fact the STM32L1 only runs thumb code. This is particularly important when using interrupt handlers as I found out the hard way.

This was hacked together in one very long night. If you notice any errors you can either open an issue or fork it and make a pull request.

If you're interested in running OpenOCD I suggest you look at this Makefile https://github.com/willprice/STM32L1-Discovery-baremetal-toolchain/blob/master/Makefile