Gripper not working?

Hi, I’ve a quad running (what I know isn’t) a Pixhawk 2.4.8, it is on firmware v4.0.2.

I’ve got a servo plugged in to aux 1 and a bec powering it. The transmitter switch is on ch 9. In the parameters I’ve set RC9_OPTION to 19 and SERVO9_FUNCTION to 28, as described in the docs (see However, the docs also say to set a few parameters that are not availiable to me in Mission Planner 1.3.70 (including GRIP_ENABLE).

Using the transmitter switch, I get no response to the servo. But if I set SERVO9_FUNCTION to 1 (RC pass thru), the servo operates fine, as expected.

Is it possible to both have a manually triggered gripper (as I do with SERVO9_FUNCTION at 1) and a gripper that can be triggered in the flight plan by DO_GRIPPER? If so, what parameters do I need to set?

For that flight controller you will have to go to the firmware download page and get, I believe, the v3 version of the firmware in order to the gripper parameter to show

I know I had to go back a firmware version or two to find the v3

Thanks Lenny.

Do you know what firmware variant I need for that board? Pixhawk1 I think, though the mission planner says its a PX4v2. So any 3.x.x version for Pixhawk1?

I bet you need to fiddle your BRD_PWM_COUNT Assuming you’re not actually
using PWM outputs on the aux channels (servo outputs i.e.), try setting it
to zero.



So this is weird. I found arducopter-v3.px4 at and it uploaded to the flightcontroller fine. I found the GRIP_ENABLE parameter and set it, then discovered my RC receiver outputs weren’t being seen by the FC. I had changed no wiring or parameters. The receiver was working fine, the transmitter showed the FC board voltage via its telemetry.

I changed back to 4.0.2 and the receiver outputs were seen but of course the earlier problem returned.

The PX4 branch of 3.6.12 firmware was the only one I could find with a arducopter-v3.px4 file.

The gripper supportr is probably disabled in boards with a 1MB bug.
That is why you need a Pixhawk1 sw version without the 1MB limitation.