# RC Lawn Mower I recently came across this [video](https://media.ccc.de/v/gpn18-95-howto-moving-objects) These crazy kids managed to rewrite the firmware to a hoverboard to make it remote controlled. Exciting stuff! I want to use this to build a rc lawn mower! # Build Log So the first thing we need to do is find an old lawn mower, clean it out, and make sure it works.  Now head over to aliexpress and pick up a hoverboard.  Once it arrives take it apart.  They come in multiple board designs. Mine uses a split board. The older model used a single board. The easiest solution is to pick up a used board on ebay. These are getting harder to find, so hopefully luck is on your side. It's possible to get a version with an unflashable chip, you just gotta yolo it and hope.  While you're at ebay pick up a ST Link v2 so we can reprogram that board. Should be a couple bucks.  Remove the bottom plastic screws and solder in a programming header.  Connect the STLink to the header using the breadboard connectors. Do NOT use the 3.3v from the USB programmer, only connect SWCLK, GND, and SWDIO.  Install the programmer software. https://www.st.com/en/development-tools/stsw-link004.html You'll need to make an account to get the download.  Download the firmware we want to flash. I'm going to use benjaf's fork built for pwm with rc steering enabled. https://github.com/benjaf/hoverboard-firmware-hack-esk8/tree/RC-Steering The binary we care about is in the build folder called hover.hex. When you are ready to flash your board. Connect the battery to the motherboard. Connect the USB to your computer. From the Menus select: - Target -> Connect - Target -> Option Bytes -> Uncheck Read Out Protection so we can rewrite the firmware. - Target -> Program and Verify -> hover.hex On success Target -> Disconnect, unplug the USB, unplug the power. Now you need a radio. I had one of these laying around. Any PWM radio should work. https://hobbyking.com/en_us/turnigy-5x-mode-2-5ch-mini-transmitter-and-receiver.html  Next up we need to weld the motor mounts onto the mower and attach some casters so it can rotate. There's a bunch of ways you can choose to do this. I used $4 harbor freight 4inch casters and some old metal from a bed frame. Make sure to use cutting oil and a cobalt bit when drilling.      Now we just gotta connect it all up.  Connect the motor wires and hall sensors to the motherboard. - Solder a breadboard connector to the left sensor board ADC1 and Connect it to the receivers signal aileron port - Solder a breadboard connector to the left sensor board ADC2 and Connect it to the receivers signal elevator port - Solder a breadboard connector to the left hall 5v (on the bottom) and Connect it to the receivers positive elevator port - Solder a breadboard connector to the left hall ground (on the bottom) and Connect it to the receivers negative elevator port Turn on the board, bind your radio, and try it out! You should be able to control your lawn mower using the right stick. ~$130 later and we can mow the grass from the deck. Much cheaper and easier I think than: https://wiki.ardumower.de/index.php?title=Ardumower_Gasoline or ripping the motors out of an old electric wheel chair + using car batteries Did I mention be safe when building your giant remote controlled spinning blade, definitely watch your toes. If I were to do this again, I would probably use larger casters and find a way mount the hoverboard motors to thicker tires. Maybe something like this: https://www.youtube.com/watch?v=Gd4ZhcLUYC0 # Video