I discovered by Saulius Lukse that uses a Carambola for streaming video and telemetry, and it gave me the idea of using the Carambola CPU to do more-sophisticated autopilot code than can be crammed into an 8-bit, 32K micro.

Obviously, there's room for some user code, because he added a streaming video server and sernet server to it. But how much? I would guess there should be quite a bit of CPU, since there won't be any Ethernet traffic to manage, but I've guessed wrong on a few occasions

And can the OpenWRT kernel supplied handle "somewhat hard" realtime tasks like reading sensors via I2C or SPI dozens of times per second?

I would expect to leave the Ardupilot board in the system because it has the timers and other I/O to run the rotors. But it would be more like an "I/O coprocessor", with the RT3052 runniing all the high-level code.

Thanks,

Ran

Hi!

The following information might be helpful for you: I added a sparkfun SEN-10724 I2C sensor stick (https://www.sparkfun.com/products/10724) to the carambola board and it's possible to read 3-axis gyro, accelerometer and compass data at 100Hz with 14% CPU load. This includes the attitude calculation (using DCM and a complementary filter). I also did some worst case latency measurements: under heavy ping flood (packet size 1000 bytes), the average latency is around 200µs and the worst case is 4 milliseconds. So 100Hz is ok (and you typically won't need more for a quadrocopter gyro. AFAIR, ardupilot uses 50 Hz). I have attached the source code that I have, so far.This is WIP, so it actually would need a little bit more polishing and documentation - but you should get the basic idea.

regards

Bernhard