For a project that I'm working on I need an extremely small, power efficient wireless device (could be radio, or some other interface) to network between a series of ATTiny85s and a larger Arduino. The communication range only needs to be about 1 foot, max. I'm currently using wired I2C, so it would be excellent if someone could suggest a radio or another device that can use the two digital pins previously occupied by the SCK and SDA lines on the ATTiny. I have those two, along with one extra digital pin available for use.

This device needs to be extremely small - this common NRF24L01 package is too big and its SPI interface uses too many pins.

Thanks for your help.

  • 1
    There are ways to interface with a NRF24L01 with ATTiny85 with reduced pin usage plus you could use a ceramic antenna and cut off the large SPI header. It is possible to turn a NRF24L01 really small.
    – Avamander
    Dec 29, 2015 at 10:59

2 Answers 2


An RF kit like this one. It's a 2-part kit, Tx and Rx separately -- each needing Vcc, GND and one pin. You need both on each ATTiny to be able to transmit and receive.

  • 2
    A similar product but a lot smaller would be the SYN115 and SYN480R based modules. These are however dumb devices, so you need to implement a protocol for them, and handle/prevent collisions, have some data integrity protection, etc.
    – Gerben
    Dec 23, 2015 at 15:57
  • Definitely. And that will eat up precious memory -- more code...
    – dda
    Dec 24, 2015 at 4:01
  • Link is dead. Instead of saying something "this one" can you give a model number that can be searched? Jan 28, 2021 at 5:13

I've also had good results with using the Mchr3k - Arduino Manchester Encoding library with those 315mhz RF kits. It has support for ATTiny85 as well.

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