Hello. A couple months ago I posted about an autonomous gliding project I am working on and I received some helpful tips on setting up Ardupilot for the mission. However, when it came to actually getting the hardware to work I ran into many issues. Since this glider is getting released from a carrier aircraft it is very small and space is at premium. The only option within our budget was the the OpenPilot Revo(not the mini). I feared that this board would give us issues but at the time it really looked like the best option. We successfully flashed the board with Autopilot and connects to MP over usb no problem.
The two main devices we need for this mission are the GPS and airspeed sensor. The GPS is the BN-220. I selected this as I saw a video where it was verified to work
The major issue with it is that you cannot power it over USB which is a problem for us as we are not using telemetry and we need to verify that the GPS works properly. The video does suggest a solution where 5V is provided via the other Main or Flexi port. We however would not prefer to do this. Is there a better solution?
The second issue which is far bigger than GPS is the airspeed sensor. We are using a MPXV7002DP analog senor as digital ones are outside of the budget. I have found resources that indicate that this sensors does work via the number 5 servo port in LibrePilot
I don’t know anything about the board but you should be able to use that sensor. You’ll need to set ARSPD_TYPE=2 and figure out what pin number that servo output corresponds to and set ARSPD_PIN.
imho you can’t get around supplying power to any of the board’s 5V pins, this is a basic requirement for powering the board and periphereals. you can still plug into usb any time to check for proper gps fix and other arming checks. however, adding a wireless telemetry via a cheapo esp8266 or a bluetooth module would likely add a lot of convenience.
@vierfuffzig Thanks for the advice. It looks like I will need to set up a voltage divider as the sensor does output 5 volts.
As for the GPS. I tried connecting to USB while the battery was plugged and my PC wouldn’t detect it. As soon as I removed the battery my PC would pick it up. Is there a work around or will I have to have telemetry?
@glassfish imho you should be able to connect via usb at any time, no matter how your board is powered. what exactly keeps you from connecting, is it the device not being found or is it no heartbeats being found from an otherwise correctly connected board?
how exactly do you power the board? batt / bec / other periphereals?
i don‘t have the fullsize revo myself, but imho there‘s a pair of diodes that separate USB from external power. might be worth checking if it‘s working fine.
mind the revolution’s Vcc pins are unregulated, so you’ll have whatever voltage you apply to one of those on all others too. depending on your exact setup that might not be ideal and bear the risk of damage when powering your GPS and other 5V-tolerant periphereals with 8,4V.
while not beeing exactly familiar with the fullsize revolution’s layout, the diodes will likely block USB sens if more than 5V is applied to the board’s Vcc.
i’d suggest rechecking your supply layout and maybe consider powering your board with regulated 5V and see if that keeps USB and periphereals alive.