Re: Puma board building diary
Posted: Mon Jan 17, 2011 6:38 am
I've been struggling with the mcu booting for a couple of days, and by asking Fred many things I fixed the issue.
The cpu wasn't exiting the serial monitor, freeems could only start after a soft SM reset. It turns out that the mcu was starting too soon and some things weren't initialized properly.
The TA card schematic has an mc34164 to keep it under a reset status until VCC reaches an acceptable level. Spin 2 should have something like that. My hack to get it working was adding a 2.2uF capacitor between the reset pin and ground.
Future tests to do (for others, not me):
* Try different values for the little RC delay. Smaller capacitance can aviod the use of a big electrolitic capacitor, but bigger resistance could lead to a too weak pullup.
Now I've freeems talking to mtx...
The cpu wasn't exiting the serial monitor, freeems could only start after a soft SM reset. It turns out that the mcu was starting too soon and some things weren't initialized properly.
The TA card schematic has an mc34164 to keep it under a reset status until VCC reaches an acceptable level. Spin 2 should have something like that. My hack to get it working was adding a 2.2uF capacitor between the reset pin and ground.
Future tests to do (for others, not me):
* Try different values for the little RC delay. Smaller capacitance can aviod the use of a big electrolitic capacitor, but bigger resistance could lead to a too weak pullup.
Now I've freeems talking to mtx...