Hi,
I have been looking at IR receivers, but there are a few things I am not clear on.
So as i understand it for a 38khz receiver I could set a pin to use PWM at 38khz connect up a LED and turn it on and off with ~420usec pluses (about 27.778usec *15cycles). And the receiver will demodulate this in to 420usec 1 and 0's. The data sheets says minimum bust length > 10 cycles.
Assuming this is correct I want to create a transponder that can send a 4bit number quickly for use a a race transponder. So i was thinking of pulsing and 8bit number with 2 lead bits, the 4bit number and 2 end bit, and using a 56khz receiver with bit lengths of 20. And calculating that it would take ~2ms to transmit. And i was thinking if the transmitter repeats it every 50ms (with a random element built in) to make sure if two device are in view of the receive at the same time they will re-transmit at different times.
I can look for the first pulse on the input pin on the ardunio then wait for 8 bits and decode it.
So does all of that sound right first of all.
Next I want the transmitter to be mounted on a micro quad which will be flying with in 1m of the receiver. so i don't think range is an issue, but I need it light weight how can i build a minimal weight IR weight transmitter, that i can easily reprogram via an external lead.
Eventually I would like to have higher time resolution than 2ms. I see IR receivers that go up and beyond 100khz. But what would be a realistic upper speed an ardunio could deal with pluses coming in from a receiver.
Really what I am asking for is a sanity check and some help in components for the transmitter.
Any thoughts gratefully received.