Drive Motors for TankPi

After a bit of testing, I found that the old cordless drill motors I was intending to use for this project have too much speed and not enough torque. I am going to have to either gear them, or alter the voltage/current to make this better as it is currently not geared at all.
We'll see what happens...

In order to get the belt to actually move, without the back drive wheel bending, I found I needed to put a bracket on the drive wheel as shown below.

I'll post again soon with another small mini-project I've been working on, and to share updates on how TankPi is doing!

Jamie

TankPi Update

After spending an entire afternoon scouring the internet last week for a method of live control over the GPIO, I found that some amazing person had written a little app using Node.js for a similar project (link to her GitHub code https://github.com/mirceageorgescu/raspi-tank). There are no instructions with the code so it was very much fiddle and guess but I got it all working in the end, with the exception of a broken motor driver board, and after blowing up 4 D cell batteries by accident.

The main chassis has hardly changed, but I now have the first track prototype on, its a bit hit and miss as it's covered in electrical tape at the moment and the track doesn't stay in the wheels just yet as I haven't cut the rubber to size in case this just doesn't work.

So all in all things are getting underway. As some side projects, I am still trying to get my LCD screens to work over I2C but there's a chip and code issue to sort out somewhere. The LED cube board is built onto a board now which is good but I need to get an Arduino to drive it, and in the future, a custom built board with a ATMega chip on it (same as on the Arduino).

Jamie

LED Cube Board

After using the LED cube by taping wires to the legs, I made a board which has 13 pins on (9 columns, 3 layers, and ground) and is all wired up for use.

Each layer on the cube had each LED's cathodes linked up together, and then to a transistor and then to ground. The transistors and ground connected to the 4 pins on the right (3 layers + ground) and each column connected to one of 9 pins on the left. The soldering and wiring underneath is a complete mess and it doesn't sit flat on the table so I'll need to stick some feet on it. Once the camera's charged (I left it plugged into the computer on, d'oh) I'll stick some more pictures up, some of the wiring and a circuit diagram.

Jamie

Blue LCD Display (x2)

Yesterday evening, my 2 new LCD displays arrived from China! I couldn't get it working until today because I needed a 10k potentiometer that I didn't have. After Googling which household items have potentiometers in, I found that there were 2 100k ones in an old joystick I had lying about. That got the screen working :D

Unfortunately using the GPIO to control the LCD meant that there was no way to use the spare ports as they were in the wrong mode (LCD uses GPIO.BCM and I need GPIO.BOARD). To get around this so I can use the LCD on TankPi, and use the other GPIOs, was to use the I2C ports on the Pi (it meant I'd used the only one up, but I think that's not a problem on this project :) ). I'm now waiting for the I2C chip to be delivered from CPC, then we'll see how that works out.

Jamie