Part 1 - 24 June 2007

Due to some last-minute hacking trying to fix rooter’s boards the day before my dissertation demo, and some really really bad connections in between the different boards, I’m now rebuilding and replacing most of the boards. I have decided to keep the regulator board and possibly the sensor board, but everything else on v2 is going on a single piece of stripboard.

This allows me to do away with one of the microcontrollers, and the (very troublesome) connection in between the main board and stepper driver board, and should hopefully leave me with a working mouse!

Here are some WIP pictures from tonight:

I’ll be posting more pictures tomorrow, and a report from the UK MicroMouse Championships at the weekend!

Part 2 - 25 June 2007

Today i finished the board for R1v2. I added two status LEDs to the power lines, one for 5v and one for 3.3v.

Also, i added the header for ICP, a RS232 header, a pair of switches, the header for the sensor board, a uC controlled LED and a hex input switch.

After the hardware was completed, I programmed a quick piece of software to allow me to read the status of the hex switch, and toggle the LED over the RS232 link.

So tomorrow the plan is to get the stepper motors running, using interrupts in the uC.

Part 3 - 26 June 2007

Today i managed to get the motors on R1v2 working properly. I also added a second LED, and wired up the rest of the header for the sensors.

Here is a short video of it running the motors on opposite directions. Tonight I’m looking at getting them working with timers and interrupts, reusing the code i wrote earlier:

Part 4 - 28 June 2007

I’ve just managed to get the sensors working in r1v2, thought it was time to update the worklog.

Sensors outputting:

Sensor input:

Sensor1 (front left): 49
Sensor2 (front right): 27
Sensor3 (left) : 25
Sensor4 (right): 26

Unfortunately, the sensor input doesnt seem too useful at the moment, as i’m getting either a lot of noise, or too little variance between the nearby and far away readings.

Part 5 - 20th - 27th November 2007
So, it was time for RoboTIC 07, and… I’d done nothing with R1v2 since June!

Since the only huge hardware problem i’d been having was with the sensor board, I decided it was time to rebuild it from scratch, and move to a more technologically advanced sensor, so… i shamelessly copied from Min4A, one of the top Singaporean mice.

So, i had decided on using the TSL262, now the problem was to find them! The only place they seem to be available in the UK, farnell, sells them for £3 each in small quantities (pn: 1182351), and since i could find them for $2.52 (about £1.25) each from Mouser in the US (pn: 856-TSL262R-LF), i decided to import a pile of them, and resell what i didn’t need. After perusing the datasheet, i found a good matching Infra Red LED (pn: 859-LTE-209), and put in an order for 50 pairs.

A week later they arrived, along with a nice customs bill, so including delivery, they cost about £2 each, still 1/3 cheaper than it would have been buying locally.

After some planning, and trying different methods of coupling the TSL262 to my ATMega32 uC, i decided to go for simplicity, and coupled the output of my test sensor directly to an ADC. The LED was connected to an IO pin set to output, and tied to ground via a 330Ω resistor.

It gave much more repeatable results than the old sensors, between 5/1024 for no wall at all, and 50+/1024 when there is a wall nearby. Since it seemed to work as expected, with no major glitches, So i moved onto a small stripboard sensor.

This sensor was tested by being plugged into the sensor board plug. Once i had it working, I soldered a sensor board connector to a second piece of stripboard sized to fit in the sensor board slot at the front of the mouse.

Once tested, I built another of the sensors, and attached both to the front and rear of the left side of the micromouse using sticky foam pads, and built a third sensor on the sensor interface board.

So, the hardware of R1v2 is now complete!

Come back soon, when i’ll be walking through the toolchain used to program the mouse, and release the full schematics of the mouse.