I need to allow two devices to communicate by generating a set of pulses (in the range of 100 to 1K HZ) in one device to be received by another device. The two devices are very near each other (say 5mm) and both devices have their own power.
I could create two pins to connect the two devices, but this means that I need to design a case that connects the two pins and make sure that they always connect in the field.
Can I transfer these pulses using a contact less method? The solution should be very cheap (less than 1USD) and low power (less than say 1mw consumption). So solutions such as NSF and BLE and .. are not suitable due to cost and power consumption.
What are some alternatives to design a way to communicate pulses between two devices sited close to each other without physical wires?