Developing for TI LaunchPad MSP430 board on Ubuntu

If you google for it, you'll find quite a few blog posts, but most of them are from 2010. But starting with Ubuntu 11.10 (Oneiric), gcc-msp430 and friends are included in the main repositories, so you can just apt-get install them:

apt-get install binutils-msp430 gcc-msp430 \
    msp430-libc msp430mcu mspdebug

There's one annoying bug in Oneiric's version of binutils-msp430 which breaks build with -ffunction-sections -Wl,--gc-sections options (which is kinda common trick in embedded world to remove unused functions and reduce code size): mspgcc #3386145. It is fixed in Ubuntu 12.04 (Precise).

I'm however still running Maverick, so instead I downloaded following Oneiric packages:

binutils-msp430_2.21~msp20110421-2_i386.deb
gcc-msp430_4.5.3~mspgcc-4.5.2-20110612-1_i386.deb
libgmp10_5.0.1+dfsg-7ubuntu2_i386.deb
libmpc2_0.9-3_i386.deb
msp430-libc_20110612-1_i386.deb
mspdebug_0.16-1_i386.deb

Then few from Precise:

binutils-msp430_2.22~msp20110716p5-1_i386.deb
msp430mcu_20110613-3_all.deb

(If you try to install Precise versions of other packages on Maverick, they want to pull upgrades to system libs, which I wanted to avoid).

and installed them manually with dpkg.

Connetcing to preprogrammed TI Launchpad demo under Linux

TI Launchpad board comes with preprogrammed demo application for temperature sensing which is touted to output temperature values to host via USB-encapsulated UART. By connecting to it via terminal you can see that it indeed sends something, but that doesn't look anything like temperature represent in ascii digits, like someone naively could expect. It turns out that it's well kept secret on Launchpad wiki pages how to make sense out of it - at least, you get advertisements for CCS and Java-based GUIs to read out the output, but not straight docs of how to use builtin demo without all those crutches. So well, wrong approach - it's your random user-friendly arduino, approach of reading docs doesn't work here, better go straight to the source.

And, here's step by step instructions:

First thing to note is that Launchpad's UART-via-USB emulation is extremely fragile. It seems that if MCU started to produce UART output but host doesn't read it out, then buffer in USB bridge just gets overflowed and it stops responding to USB. So, if you want to get it working, follow each step below precisely and if any issue happens, restart from beginning (with unplugging LaunchPad).

1. If you have plugged LaunchPad into USB, unplug it now to make sure you start with properly reset device.
2. Plugin the board into USB, general-purpose green and red should blink interchangeably. The demo app doesn't yet sense temperature or sends it out yet in this mode.
3. Execute stty 2400 -F /dev/ttyACM0 . That's right - the demo app communicates at 2400 bit/s data rate and using any other rate will produce garbage input. (One reason for such low speed is that LaunchPad's MCU actually doesn't have hardware UART, it is emulated in software).
4. Run hexdump -v -C /dev/ttyACM0 . It shouldn't produce any output yet.
5. Press GPIO button. The demo app goes into measurement mode and starts to send out temperature in Fahrenheit as raw bytes over UART. Try to heat/cool air around the board to see values change.

Sample output:

00000020  60 60 60 60 60 60 60 60  60 60 60 60 60 60 60 60  |````````````````|
00000030  60 60 60 60 60 60 60 60  60 60 60 60 60 60 60 60  |````````````````|
00000040  60 60 60 60 60 60 60 60  60 60 61 60 60 61 60 60  |``````````a``a``|
00000050  61 60 60 61 61 61 60 61  61 61 61 61 61 61 61 61  |a``aaa`aaaaaaaaa|
00000060  61 61 61 61 61 62 61 62  62 62 62 62 62 62 62 61  |aaaaababbbbbbbba|
00000070  62 62 62 62 62 62 62 62  62 62 62 62 62 62 62 62  |bbbbbbbbbbbbbbbb|
00000080  62 62 62 62 62 62 62 62  62 62 62 62 62 62 62 62  |bbbbbbbbbbbbbbbb|