SparkFun Forums

[paulrbarnard]

I'm having problems with the SparkFun Razor Mo IMU. When connected to a Mac Computer (tried several different ones, laptop and desktop) and the Mac is Rebooted the IMU locks up. The only way to recover is to physically reset the IMU or unplug and plug the USB cable.

Things looked at so far
1. The Power remains connected from MacBook to IMU. It remains solidly at 5V (measured with oscilloscope)
2. Reset does not activate on the IMU (measured with oscilloscope)
3. Unloading and reloading the kext on the Mac has no effect
4. The main loop in the Arduino code stops running. I wrote a test app that just flashes the LED and it stops flashing

Is there some kind of programming control like DTR pulse on other Arduino boards that might be putting the Razor into an unknown state. The Mac USB obviously goes wonky when the computer is restarting.

Any help or suggestions gratefully received. I'm using these for data logging in inaccessible locations and if the MacBook restarts for any reason the site needs a visit. An external watchdog might be the only option but thats going to need site visits in three different countires

[paulrbarnard]

Looks like the problem is caused by M+ and M- both going low during the Mac Restart. Looking at the data sheets this might be triggering an interrupt in the Atmel SoC. Anyone know if the firmware source for the device is available? I'm assuming there is some base code for Arduino.

[darrellg]

There is a Github link on the product page.