I2C on the Beagleboard xM

It's really easy driving I2C™ devices from the Beagleboard. I'm using the Trainer-xM from tincantools; that takes care of shifting voltage levels from the 1.8v used by the Beagleboard to the 5v levels that my I2C boards expect.

There are a few I2C coding examples on the web; since my BB image includes python and geany, I've written the I2C code in Python and can edit and test it on the board. Much faster than an edit-compile-upload-test cycle.

Here's the code:

import i2c, time

extender = i2c.I2C_device(0x20)
extender.begin_transmission()
extender.send(chr(0))
time.sleep(5)
for count in range(0, 16):
    extender.send(chr(count))
    time.sleep(0.5)
extender.end_transmission()

See it running.

From little Acorns do great Raspberries grow

I recently re-discovered an old friend: the great-great-grandfather of the ARM-based Raspberry Pi . It's the original Acorn micro-computer (ca. 1979). Acorn went to on make a succession of machines, including the BBC Micro and the Archimedes.

The Archimedes was based on a proprietary RISC chip which is the grandfather of today's ARM chips. The Raspberry Pi is part-funded by Dave Braben, who wrote Elite (arguably the most famous BBC micro game). Broadcom, who are make the Pi's ARM chip, have strong historic links with Acorn.

I'll try the micro out in a day or two; I still have the (fairly minimal) original documentation, and there is more information on Wikipedia. The micro was arguably one of the best investments made by Cocking and Drury; my colleague Jonathan Barman used it to learn assembler, and went on to master 370 Assembler, through which he landed us a major contract with a national brewery.

Blogging from the Beagleboard

I'm posting this using the Midori browser running under a custom Angstrom image on my brand-new Beagleboard Xm. The Beagleboard continues to amaze me.

Setting up a fresh sd card with a custom image has proved a little tricky; it's taken about 4 hours, of which one was spent waiting for a very slow Kingston microSD card to get configured on first boot. I'll write up the process and post it later this weekend.