Hi,
This hack has just occured to me -
- When the IR Receiver you are using detects a valid 38Khz signal, it initially changes its output to show it has a valid signal
- Shortly afterwards it will change back because the continuous 38Khz signal is not within the signal rules (page 5 of the datasheet)
- From this point onwards, the receiver will ignore the presence of the 38Khz signal
Now for the hack -
If someone happens to walk in front of the receiver, it breaks the continuous 38Khz signal briefly.
As soon as the person passes and the receiver picks up the 38Khz again, it assumes - 'Hey this is a good 38Khz signal' until after a short period it realizes - 'No, its not'. The good news is that during the brief 'Hey this is a good 38Khz signal' the output will change allowing you to count traffic.
Its a bit of a hack, but it is based on a valid interpretation of the datasheet.
Using this method you could use a separate 555 timer to generate the constant 38Khz signal, this would free you from running wires between the transmitter and receiver.
Duane B