Accelerometer Troubles

I tried out an accelerometer from ST Microelecronics today. It is an evaluation kit for a sensor poetically named LIS3LV02DL. The kit itself is called EK3LV02DL. This probably means something to someone, but too me it is just short for 3-axis digital accelerometer.

The evaluation kit has a USB connection so it seemed that it would be very easy to get the communication up and running. I do not have a Windows machine so I could not test the demo programs that came with the kit. Instead I hacked together a small program to communicate with the device using the fairly simple communication protocol.

The procedure should be easy, the USB device shows up on my Mac as a device in the /dev directory and all you have to do is open it and read and write to it - or so I though. This has worked well for every other USB device I have tested, but in this case nothing happens. Well almost. I managed to get my program to crash by pressing the reset button on the kit. Always something.

I suspect that I do not have the correct drivers. Most other devices use the FTDI USB to serial converter chip, but this is not the case for this evaluation kit. Instead it uses something called the ST7-USB bridge. ST7 is the microcontroller on the evaluation kit and apparently it comes in variants with USB on the chip. I am not sure there exist any drivers for OS X so I might be out of luck on this one. But who knows. A colleague of mine who had tested a similar evaluation kit tried to convince me that it takes at least three days of hard work to get it to work, so I still have two more days to go.