I have a project where I need to send a wireless signal to one of several receivers to turn on an LED.

One transmitter, several (many) receivers, each with an LED. The receivers need to have low power consumption.

Transmitter side:

  • Raspberry pi
  • HT12E encoder
  • 433 mhz transmitter

Receiver side:

  • 433 mhz receiver
  • HT12D decoder

Each individual receiver would have a unique, fixed address.

I was hoping I could use the raspberry pi to dynamically set the address of the encoder to match the relevant receiver, but I cannot figure out if this is possible. The address of the HT12 is adjusted by connecting Ax pins to ground. Can I do this with

Is there a better alternative to this? Can I use the Raspberry to simulate the signal from the encoder? The system must be possible because it is similar to restaurant pagers

This is how I am envisioning it now. Am I understanding correct? Do the address on the transmitter side match with the address on the receiver side?

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EDIT: Added sketch of wiring.


1 Answer 1


Use a pull down resistor (270R-470R) for all A0 to A7 address points to earth. Then directly connect A0-A7 to GPIOs on RPi. Initialise these GPIOs to OUT and OFF, that will mean all address points run to earth and hence address of 00000000. Switch on respective GPIOs to required address. Voila.

  • Thanks, Pete. It was exactly something like this, I had imagined. Do you have a link to a pull down resistor I could use? What you are saying is that I connect each encoder leg to a GPIO via a resistor, is that right?
    – Hjalte
    Dec 14, 2020 at 12:29

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