This page gives resources for using a transmitter chip and receiever chip on fabbed boards for one-way communication.
These chips are not as fast or versatile or long-range as the nrf24L01 modules, but they can be much simpler to use. They are
devices used for applications like garage-door openers, or other short range low data rate purposes.
These chips all require an external clock, usually a crystal. It is also possible to use an external clock reference, such as the PWM output from
a tiny AVR chip. For the transmitter chip described on this page, the clock can be a 10MHz PWM signal derived from an AVR with 20 MHz crystal,
leading to transmission at 32 times that frequency, 320 MHz. The receiver clock is another AVR chip PWM at 5.00 MHz. Transmitter chip is clocked by a 10.000000 MHzPWM on t44, using the 20.000000 MHz resonator as clock.
This results in a 320.00000 MHz transmission frequency. The c-code does two things: sets up the PWM and modulates the
signal through the ASK (amplitude shift keying) pin of the MICRF102 at 500 Hz. When the button is pushed, the modulation frequency changes.
The tiny 44 code sets up a 5.00 MHz PWM, using 20.000 MHz resonator. The code also watches for a change of frequency on the received low frequency signal
at the DO pin of the MICRF002 and lights an LED when the button on the transmitter is pushed and the frequency shifts. Note that both of these chips are on the way to obsolescence! I will have a few of these chips in the inventory at Harvard.
If you would like to explore this solution, please contact me for chips and more details. (Rob Hart, hart@physics.harvard.edu)
It is time to look for another cheap and simple solution (like the MICRF112/113 and MICRF220) or to move to the NRF24L01 for this type of application.