Re: [Paparazzi-devel] Magnetometer freeze problem occurring AR Drone 2.0

[opersupport]

Hi everyone,

I've managed to get around the magnetometer freeze problem by figuring out
how to reset the navigation board properly in software. From reading
previous posts, it seems that there was some way to reset the navigation
board with a GPIO pin, but the question was which one? Someone suggested
GPIO 181 was the way to do this but this actually controls the bottom LED
value. Using the GPIO command I did a few tests and this is what I came up
with:



PIN 1 to 8 refers the J2 connector between the navigation board and the main
board as shown here:
http://3.bp.blogspot.com/-eHypEWpknKc/US125t50ONI/AAAAAAAAL7A/XnoOndqydag/s1600/ardrone04.jpg
(from http://diydrones.com/profiles/blogs/ar-drone-2-0-teardown)
GPIO 177 –d lo (1 and 0) – causes PIN 6 to go high/low
GPIO 178 –d lo (1 and 0)  - causes PIN 2 to go high/low
GPIO 179 –d lo (1 and 0) -  causes PIN 4 to go high/low
GPIO 180 –d lo (1 and 0) – causes bottom facing LED to turn OFF (0 ) and
GREEN ( 1) 
GPIO 181 –d lo (1 and 0) -  causes bottom facing LED to turn GREEN (0) or
RED (1)

It turns out GPIO 177 is the pin that is used to reset the PIC navigation
board. By default, it is set to HIGH, when set to LOW the navigation board
is held on reset. Set it back to high again to reset the board. You will now
have to send a \1 over serial to the navigation board to command it to send
data back again.

So in summary:
1) When magnetometer freezes, make GPIO 177 go from 1 to 0, then set it 1
2) wait a few milliseconds for a full reset
3) echo –e –n “\1” > /dev/ttyO1 (this is the command line way but you could
always re-initalize it as in the paparazzi source code).

Unfortunately sometimes I need to constantly reset the navigation board,
like, almost every 20-30 seconds. A reboot seems to fix this when this issue
does occur.

NOTE: This was tested with the latest firmware update.



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