Garage Sensor
Assembly
First a simple hardware layout. An ATTINY13 creates a data stream, sends to to the transmitter on one board. The receiver on the 2nd board picks up the signal, sends it to the 2nd ATTINY13 for decoding. Finally the ATTINY13 controls 2 LEDs, one fora Door Open/Closed, the indicator, the other LED to indicate loss of signal. I figured the signal loss indicator was a good idea because, that way if I lost the transmitter or it’s signal, I could differentiate that from a safely closed garage door.
The design of the data stream was the next task. I only needed to send a single bit of data, but I wanted to include error detection and I wanted a data stream that was easy to decode. The data part was easy, single data bit + parity bit. ie 10 for door open and 01 for door closed. To make decoding easy, I wanted unique start and stop bits that did not show up in the valid data stream. Thus, 11 for the start bits and 00 for the stop bits made sense. End result: 110100 = the data stream for ‘door closed’ and 111000 = the data stream for ‘door open’.
At this point, I threw together a breadboard prototype to validate the hardware and software configuration:
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http://www.jenrathbun.com/Electronics/?page_id=538
Don
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