Using Newlib With Stellaris Launchpad

December 18, 2012 by Mike Szczys 20 Comments

using-newlibc-with-stellaris-launchpad

[Brandon] is taking us further down the rabbit hole by demonstrating how to use newlib with the TI Stellaris Launchpad. This is a nice continuation of the framework he built with his post about using GCC with ARM hardware. But it is most certainly one level of complexity deeper than that initial article.

Using newlib instead of glibc offers the option of compiling C code that includes system calls common when coding for computers but which are rare in embedded systems. Using something like printf is generally avoided because of the overhead associated with it. But these processors are getting so fast and have so much RAM that it may be useful in certain cases. We briefly thought about implementing malloc for creating a linked list when working on our STM32 snake game. [Brandon’s] work here makes the use of that command possible.

The process starts by adding labels for the beginning and end of the stack/heap. This makes it possible for functions to allocate memory. After taking care of the linker script changes you must implement a few system call functions like _sbrk.

A Study Of GCC And The TI Stellaris

December 4, 2012 by Mike Szczys 9 Comments

hard-look-at-stellaris-and-gcc

There are several things that we really like about the TI Stellaris. We think the peripheral library — called Stellarisware — has a pretty intuitive API that makes it easy to get into. But we’re also quite impressed that the software comes with makefiles that build the libraries and examples using your own GCC cross compiling toolchain. We spent quite a bit of time pawing through those makefiles and the makedefs settings file to figure out how TI was doing things. Now if you don’t want to do that sleuthing yourself you can head on over to the GCC with TI Stellaris Launchpad guide which [Brandon] just published.

Shown above is the helpful chart of compiler flags which he pulled from the files with his added comments on what each does. He did the same for the linker flags, and then discusses the program calls made during compilation and linking. He then delves into how the driver library on the chip’s ROM can be accessed in code. This is just the first in a four-part series he plans to write. We can’t wait to see what he has to say about the hardware FPU as we haven’t had time to explore that for ourselves quite yet.

STM32 F4 Discovery Tutorial Using Open Source Tools

September 27, 2012 by Mike Szczys 19 Comments

[Pulko Mandy] got his hands on the new STM32 F3 Discovery board. He’s a fan of the open source tools just like we are, so he posted a guide covering the use of an open source toolchain with the F3 hardware.

This board was just announced earlier this month but there is already support for it in OpenOCD. It’s not all that different from the F4 board, which we would think made the process a bit easier. [Pulko] is using the Sourcery CodeBench Lite toolchain, which works for pretty much all of the ARM chips out there. It is GCC based and comes with GDB for debugging (along with all the other tools you would expect). He did created his own Linker script and startup code. These are crucial for ARM so it’s nice that he provided them for us. He finishes up the guide by showing how OpenOCD can be used to flash the code to the chip and how it works with the debugger.

[Photo source]

Parallax Shows Love For Open Source: GCC + Propeller

June 20, 2012 by Mike Szczys 35 Comments

Parallax has done something that is unthinkable for most microcontroller manufacturing companies. They’ve decided to throw their support behind an open source toolchain based on GCC. That’s right, instead of fighting to get your code compiling on a platform whose example code uses crippleware, you can actually download, compile, and start using this toolchain without code size restrictions or other unfavorable limitations.

Why does this matter? One example that comes to mind is ChibiOS and the STM32F0-Discovery board. We’ve been playing around with that board recently and found out that the Atollic 8k code-size limitation prevents you from debugging ChibiOS. So you either pony up the registration fee, or go though at least a little pain (a lot depending on your skill level) to move to an open source solution. Here that’s not going to happen because you start with a GCC option from the word ‘Go’.

So join us in a round of applause for good decisions. Bravo Parallax! This Beta test targets the P8X32A Propeller chip but we hope it’s so popular that the rest of the line gets its own support.

[Thanks Devlin via Adafruit]

Template For Building STM32F0-Discovery Project In GCC

June 17, 2012 by Mike Szczys 17 Comments

Yep, that blue light is blinking and I made it happen. I’ve been hard at work since I got my free STM32F0-Discovery board in the mail. Most recently I put together a starting template for building STM32F05x project on Linux. You’ll still need to install your own tool chain (I’m using the Code Sourcery G++: Lite Edition), but this makes it a snap to compile your projects with support for STM’s peripheral libraries.

As for programming, you may remember that I added support for writing to RAM in the stlink project. I’ve ~~wasted~~ spent a ton of time trying to get support for writing to Flash into that project. It’s just less of a hassle to use stlink than it is to work with OpenOCD. But I’ve really hit a wall getting the flash loader code to work. If you want to check out what I’ve done so far in that area I committed a very messy branch (see the commits for what code changes I’ve made).

In the mean time you can use OpenOCD to write images compiled with the template to your device. I included the ‘make program’ option in the Makefile to do this from command line. If you need help compiling OpenOCD check the readme in the template repository.