Tuesday, 5 March 2013

More developments - moving quickly

Today was a quite intense day for the Cycle Sound project.

Started off with testing the XBee connection. This had been done very softly before and needed deeper understanding and testing.

Four things needed checking: a) all the pins of the XBee shield are sending; b) the analog pins are sending analog signal; c) the remaining pins of the arduino, despite not connected to the XBee, also send signal; d) Pure Data is receiving all signal, parsed as desired.

There is, however, another point to be tested: multiple simultaneous signals being sent and received and respective correct parsing. For this multiple connections to the arduino are needed.

After checking these points I proceeded to designing all the separate PCBs and a shield for connecting them to the arduino. As it was done their production starter: laser printing in photo paper, cutting the prints, cutting the copper board, transferring the prints to the copper board, etching the board, removing the toner, drilling and finally populating the boards.

I made a couple of mistakes on the way. Nothing serious.

1st - I didn't invert the shield drawing for printing. The others weren't important to invert as they were symmetric. And they were all printed in one go. I only realised this when I was already peeling the photo paper after the transfer had been done. Therefore, I had to go back to Illustrator, invert the image, print, cut the print and a new board, make the transfer again and so on...

2nd - the two very small hall effect sensor PCBs for the brake levers take a ratiometric hall effect sensor each. I assumed that it was going to work in the same way as the switch. Clearly I was wrong. But, luckily enough, I didn't have to make new PCBs for this. The problem was that I didn't test the sensors before making the PCBs. Anyway the difference was that they proved stabler without the resistor. I actually didn't test with different resistors but assumed that they would only interfere. Therefore I simply didn't insert the resistor.

The shield was done with surprising accuracy. However, the pin connectors aren't yet in my posetion. As soon as I get them I'll populate the shield. With it done, I can connect all PCBs to the arduino and make a full range test of the XBees, taking it to the park and making its first walk outdoors.

Hopefully, the brake calipers will also arrive soon and the bicycle will be able to join the XBees for a test drive.

No comments:

Post a comment