Saturday, November 20, 2010

Bluetooth Thermometer R2.0


It's been a fair while since I've posted anything - Things at school are starting to wind down (or up, depending on how you look at it) in preparation for the end of the semester, which is now a mere two weeks away.

The Bluetooth thermometer project I started a couple months back has recently been revived and will be making a cameo appearance as my final project for my Introduction to Electronics course. Since it is now a school project and I can actually justify investing time in it, I have decided to make quite a few changes, including a new microcontroller, a firmware overhaul, and finally a PCB.

Figure 1.0: R2.0 PCB Partially Populated

After playing Altium for four hours straight, I finally had a schematic and layout that I was happy with, and transferred it to copper. Top left is the ICSP port and the power connector sitting beside the PIC16F628 MCU. The power supply is in the top right, and in the bottom center you can see where the Bluetooth module will sit. At the moment there are wires carrying +3V3, GND, TX, and RX to a breadboard that has my old Bluetooth module in it. Once I know the layout is good I'll solder one of the new modules I've ordered straight onto the PCB, but at $15 a module that won't be happening until all the bugs are gone and the layout is finalized.

Unfortunately, things don't appear to be off to a great start: as things stand I can't even program the PIC. I'm not sure why, but the programmer isn't able to communicate with the board. I did manage to get it to work once, but that was it. Everything seems to check out okay, but I have a feeling there's a short hiding somewhere.

Schematics, Gerbers, Firmware, and the whole 8.226 meters will posted on my website:

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