I have been playing with Walkera Runners for some time and have even wrote two books that are up on Amazon. My curiosity got the best of me so I started building a new quadcopter that was based on the SPI F3 controller, Lumenier PDB, and the Taranis XD9 Plus w/ X4R receiver. I had chosen the X4R because of it’s size and because it had SBUS. Was I ever happy that I did because I was surprised at the control responsiveness that the combination gave me.
This got me to thinking, why not wire up one of my Walkera Runner 250s to the Taranis XD9 Plus radio and X4R receiver? Everbody knows this is not possible running the factory Walkera firmware, but I have already put MultiWii 2.4 on all of my Walkera Flight Controllers. Now it was just a matter of working out which UART RX pin to solder to connect to the SBUS signal lead from the X4R and pick up +5V and Ground to power up the X4R receiver. The diagram shows where the RXD3 Pin is on the AT2560.
Once I located the UART pin I wanted to use, it was time to get the soldering iron warmed up. I had decided to minimize my risk of a major screw up by only soldering to one pin on the AT2560 and not pull VCC or GND off the controller. I had decided also to run it to the top side of the controller where there was more space in the case for the additional wires. You can see in the diagram, that I ran the wire through the ISCP pin holes to get to top side of the board.
I had selected “Wire Wrapping” wire to use for this because of how thin the wire is and so it should be good for the three connections. You can see on the back side, I decided to pick up power and ground off the GPS connector to minimize the risk and also this way I have my three wires running to a nice and clean Servo Connector header.
Three simple connections and this controller is wired for SBUS!
Next post I will show how I modified the MultiWii 2.4 config.h file to enable the SBUS in the firmware. My new X4R will be arriving in a few days and then I will post a video on the test flight.
This is just one reason why I ported MultiWii to the Runners. Open Source opens up all kinds of possibilities!