Can I operate more than 2 servos with APM 2.5?

Posted by Falcon on July 13, 2015 at 6:02pm

I need 16 channels of RC control for my surveillance rover (flood lights, IR lights, vTx On/Off, camera select, cam PT&Z, plus more).  Seven channels are gimbals and pots while the other nine channels are relays and a video source switch.

I'm using a DragonLink and a PPM Encoder to get 12 channels, and verified I can use A10 & A 11 for two RC Relays via the APM 2.5 and 3DR 915mHz Telemetry.

Is there any way to control more servos through the Telemetry?  I see seven servos listed on the Flight Data > Servo screen.

The Rover Wiki's Optional Hardware/Servo section included the following: "On Plane the servos may also be connected to any available channel RC1 ~ RC8 on the back of the APM."  

   Is that option available on the Ardurover firmware?

   Are they just feed-through from the RCRX?  

   Is there any control of RC1-RC8 via the APM?

I appreciate any and all comments and responses.

Falcon

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Replies

  • Falcon July 24, 2015 at 3:54pm

    Hello Grant, and thank you for responding,

    If I'm limited to those two servos, I could make use of relay outputs.

    I see the 8 pin sets on the end of the APM 2.5 marked INPUT, adjacent to the GPS connector.  Which are the other 3 Input channels?

    I see the four relay parameters at http://rover.ardupilot.com/wiki/apmrover2-parameters/#relay__parame....  Each one has only one choice for the AMP 2.x (VALUE-13  MEANING- APM2 A9 pin).  If I set Relay 1 to "13", what VALUE would I set to Relay 2, Relay 3, & Relay 4 to control three more relays?  

    As TTL outputs, can you confirm I should be able to read 5v against the GND pins on these AUX outputs.

    I ultimately want to control four relays with the SERVO buttons on the Flight Data/SERVO screen.  What parameter changes would be required to control these relays?  Do those servo buttons (5-11) correspond to any specific controls.  

    Thank you again

    Falcon

  • Developer
    Grant Morphett July 23, 2015 at 5:53pm

    We support 11 channels on an APM2 for input.

    We are limited to 10 output channels  (channel 9 is not available) on the APM2.  2 Channels are dedicated to steering and throttle.  The rest can be used arbitrarily. 

    You could use the AUX pins and use GPIO (TTL output but no pulse train) and use DO_SET_RELAY and DO_REPEAT_RELAY via telemetry to control those. 

    http://copter.ardupilot.com/wiki/mission-planning-and-analysis/miss...

    We have allowed for up to 4 relays 

    http://rover.ardupilot.com/wiki/apmrover2-parameters/#relay__parame...

    to be defined however there are 9 pins in total A0-A8 pins to connect to meaning more pins available then the software can access at the moment.  We could add more parameters for more relay outputs if required.

    Note this is TTL only so very small amps - its a switch.  You would need to connect  a relay that takes a TTL input but then is powered by something else to do the actual switching.

    Let us know how you go.

    Thanks, Grant.

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