23rd Sep 2007

After 1 and half week's work, I finally implemented my integrated circuit (the original with bluetooth) with power and ground planes. I added a push button in the bluetooth circuit for reset purpose. The following is the PCB footprint.


The following rules applied to the design:
1. Digital and Analog ground should only be connected together at the common ground (ground that is directly connected to the voltage regulator)
2. Since the power and ground of the temp. sensor is supposed to be separated from the rest of the circuit, the 5V supply for temp. sensor and ground should only be connected to the rest of 5V supply circuit through the main power supply and ground
3. 9V voltage regulator only supply to heating element which is the only analog element in the circuit, so the GND should be connected to the rest of the GND plan only through the main power supply ground

At the same time, Soon and I are working on the design of the display on the pajama. We are having the idea using color changing only for some assessories on the clothes. At first, the idea was to make some flowers using gauze. It is very thin, and even wrapping several pieces together, the heat can still distribute very quickly to its surroundings. He has made some samples, but he sew the yarns crossing each other without considering that yarns are conductive and crossing them will cause short circuit. And we also have the idea of using butterfly knot on the clothes or we could paint the cute patterns using silkscreen.

I will be soldering the pcb board during the weekend, and then test it out.

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