September 27, 2014

Broken and fixed single-wire receiver with the CC3D

I messed up today. Big time. I was preparing to wire a Fasst S-BUS receiver to a CC3D. I do this by removing the servo connector and soldering the wires directly to get a more compact build. I'm using the Corona R4FA-SB which can either operate in 4-channel PWM mode or a "special" mode with S-BUS. PPM and RSSI-PWM outputs. I intended to use it in special mode with the S-BUS wired to the CC3D.

However, I manged to break it while removing the servo connector pins. The only important soldering pad, the S-BUS one, was broken away from the receiver. This is catastrophic, it might mean that the receiver is ready for the garbage bin.

Lost soldering pad
I managed to track down a new location to possibly solder then S-BUS signal cable. A small area between two tiny surface mounted resistors (I think). So I tried it out.

I soldered the signal cable and the power cables. Wrapped it in heat shrink and added a small bead of hot glue to avoid any possible stress on the tiny signal cable. But when I hooked it up to the CC3D there was nothing.

But I decided to go to Google and quickly realized that you can use the PPM as input to the CC3D as well. It's connected to a different input port on the CC3D and it comes with less precision and higher latency than S-BUS but it'll have to do for this build. Some cutting and soldering and configuring of the CC3D and it worked! Turns out you need to use output channel 2 which carries positive PPM.

CC3D installation with receiver, hidden below

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