I'm looking for a reference for the APM2, in one place. It's hard to find everything with bits and pieces strewn all over the forums and wiki.
Couple of questions:
1) What are the ways the APM2 is powered? One is via USB, and obviously it gets power from the ESC when flying, but if I'm using it on the bench, what's the best way to power it up?
2) I'm trying to get a couple digital radios I have working with it. In isolation, they work fine, but I couldn't get a link established with the APM2. In a comment on a forum post, someone said "be sure USB isn't connected", but I'd like to know for sure if having USB connected prevents the other serial port from working (if so, that's kinda irritating, as USB is a convenient source for power and other testing).
Thanks.
Replies
The USB is converted to serial in the APM, it's not a true USB solution. The telemetry UART and the USB are on the same pins. So USB and telemetry will for sure not work at the same time.
I don't see why you couldn't use USB power though. Just make a USB cable with the D+ and D- lines removed. Or you could get one of the many cheap plug-into-the-wallsocket USB ports and use a regular cable.
The latter is probably a better solution as computer USB power is very noisy and dirty, which can cause problems with the GPS and other sensors.
I meant to add: I decided to connect a serial adapter directly to the UART0/2 port to remove the radios from the equation; it's still not working. I tried both 57600 (brand new APM2), and 115200, and setting the serial baud rate parameter via APM planner. I also tried reversing the TX/RX pins, just in case.