I have a project where I need to remotely control up to 128 individual relay boards within a maximum 30 meter radius. I need each of these wireless relay controllers to be uniquely addressable to ensure the correct relays are opened and closed.

Ideally, quiescent power consumption for the relay remote controller circuit when not in use will be a few microamps and just a few milliamps when receiving or transmitting. I only require the ability to remotely open/close each relay based on its unique ID and to read back the overall status of each unit periodically. There is no need for a full blown MCU at each relay node (which usually means higher cost and power). I’d like to find a low-power wireless modem with the ability to interchange just a few bits of status and control information no more often than once every few seconds to conserve power. I need an integrated circuit that implements the radio, modem and digital I/Os, ideally for a few dollars per unit in volume.

I’d like to use an Arduino compatible board to supervise the array of relay controllers as a central management point.

Can anyone suggest a chipset or module that I can use for this purpose?


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  • \$\begingroup\$ Raw 433 MHz modules with some error-resilient protcol; or NRF24L01+ (or a clone or variant). \$\endgroup\$ – Wouter van Ooijen Jul 4 '18 at 21:12

433 MHz seems to be perfect fit for this application. There are tons of modules available on the web. I suggest doing your own research and then editing question, because right now it looks like shopping question that is OT on this site.

Here are some configuration options to help you narrow your search:

  • Not a "full blown MCU" but tiny MCU + Rx module + Tx module;
  • Tiny MCU + transceiver module;
  • MCU with built in transceiver module (e.g. BC48R2020);
  • Transciever module + some shift registers and logic chips to detect 7 bit address and execute 1 bit command;

Note that cost-wise the second solution is probably the best, despite your aversion to using MCU.

  • \$\begingroup\$ While there exist halfway decent 433 MHz radios, most of those sold are horrible and will require quite a bit of logic to decode - pretty much anything that operates without a long list of registers needing to be managed by an MCU is very primitive. Typically also the only decent ones are those which are transceivers not dedicated transmitters or receivers - but this application requires a transceiver anyway. In contrast, 2.4 GHz radios tend to be far more sophisticated, doing more of the work in the radio IC, and often actually cost less. \$\endgroup\$ – Chris Stratton Jul 5 '18 at 4:50
  • \$\begingroup\$ You mean like that NRF24L01 @wouter-van-ooijen suggested? Yeah, it is pretty cool device, I've never seen anything like that before. However this particular application is so extremely primitive you don't actually need much logic. The protocol can be as simple as sending 1 byte with 7 bit address and 1 bit command ("toggle your state"/"return your current state"). Can be done in ATTiny or even with 3-4 logic chips. \$\endgroup\$ – Maple Jul 5 '18 at 5:02
  • \$\begingroup\$ Radios more primitive than the nRF24L01 generally require software algorithms to reject noise and slice the data, so they're actually harder to apply well, since the barebones radio does less of the work. They also generally aren't transceivers capable of transmitting a reply. While nearly comparable SPI-controlled 433 MHz radios exist, they're more expensive and have more limited software support. \$\endgroup\$ – Chris Stratton Jul 5 '18 at 5:05
  • \$\begingroup\$ Great suggestions. I'm headed down the "Tiny MCU + transceiver module" path, using an Arduino and 433 Mhz. CC1101 module. This appears to have the advantages that I can quickly prototype a build using off-the-shelf components and later create a custom PCB as needed. \$\endgroup\$ – rbraddy Jul 6 '18 at 0:04
  • \$\begingroup\$ Take a look at TinyDuino and Adafruit Trinket. You said yourself, you don't need big MCU. These are Arduino compatible but tiny and relatively cheap. There could be other bare minimum Arduino clones that I don't know about. \$\endgroup\$ – Maple Jul 6 '18 at 0:47

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