As mentioned in an earlier post
I'll try to do one small PCB project every week and then send for PCB's of it every Monday.
Last weeks board was a simple breakout board so this week I'm planning to do something a little bit more elaborate. I've been playing with programs emulation Conways Game Of Life (http://en.wikipedia.org/wiki/Conway's_Game_of_Life
) since the early 80'ies on computers. But now is the time to make a hardware implementation of it.
A GameOfLife in hardware is certainly not a new or unique idea, Adafruit is selling a kit (by Dropout Design) for $17 with 4x4 pixels that can be linked into larger arrays with more pixels.
This weeks PAW will be a similar board, but SMD and using a small and cheap 14 pin PIC as the board microcontrollers. Unlike the Dropout board that have an elaborate communication between the boards to determine the next state of the grid my boards will merely be slave boards that only displays what the master tells them to display on the leds.
So one of the boards in the array of boards will have a more powerful PIC on it that will act as the master and send the grid updates to all slave controllers. The master board will probably also have a USB port for both power and maybe to upload data from a PC to be displayed on the GolGrid array.
Each 5x5 cm board will have 16 leds in a grid of 15mm. This means that if the boards are separated by exactly 10 mm the spacing between the outer leds of adjacent boards also will be 15 mm - making up a nice even grid of leds.
To easily get the distances between the boards correct I'll use standard paper staples since they are 13 mm wide (crown width) so if I put vias 1.5 mm from the edge of the board I can just plunk down a staple and get the 13-1.5-1.5=10 mm distance and at the same time transfer power and data between the boards.
Three staples in each direction is enough for VCC, GND and a common databus. Having a common databus means that each board needs to have a board number or board coordinate stored in its eeprom so it can filter out just the messages that are meant for it.
I'll probably use a PIC16F1824 which cost just over a dollar. Add $0.60 for leds, $0.30 for resistors and $1 for the pcb and the parts cost for a board in small quantities is only about $3 to $3.50.