Build Log: Robotising a RC tank (first attempt)

[ecat]

If you need more servo outputs it should be possible to combine the Adafruit board with this idea ...

Drive 10 Servos using only 2 Arduino Pins - DIY Drones

You need to remove the servo drive code from the Adafruit library and change the linked 4017 code to use pins 9 and 10 instead of 9 and 8, then connect the 4017 circuit to the Adafruit servo 1 and 2 control pins. This would give you 4 motors and up to 10 servos at an extra cost of around £2. I've used the 4017 idea before with a PIC32 controller, it worked well.

If instead you just need to drive one more motor/solenoid you could use a transistor on one of the free d0, d1, a0..a5 pins to give a single direction drive, or two of the pins + an inverter chip and another L293D, as on the Adafruit board, to drive 1 motor both forward and backwards.

And if you wanted to be really sneaky you could perhaps wire a 2nd Adafruit board up in parallel to pins d4, d7, d12 and GND but connect one of your free pins to the second boards d8 connection and get yourself an extra 4 full motors - N.B. Each additional motor will also require one of your additional free pins and some code to drive it for Enable/Speed control. Again you would need to modify the Adafruit library but the changes shouldn't be too tricky*.

*Shouldn't be too tricky*: the famous last words of many a programmer :(