R1v2 – Rooter Version 2 – Worklog part 5

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.

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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.

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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.

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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.

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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.