user15677: 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.

user4628: 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.

user15819: 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.

15677: <p>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.</p>

<p>This device needs to be extremely small - <a href="http://www.miniinthebox.com/upgraded-2-4ghz-nrf24l01-wireless-transceiver-module-for-arduino-black_p683437.html" rel="nofollow">this common NRF24L01</a> package is too big and its SPI interface uses too many pins.</p>

<p>Thanks for your help.</p>
 4628: <p>An RF kit like <a href="http://www.elecfreaks.com/estore/315mhz-rf-link-kit.html" rel="nofollow">this one</a>. 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.</p>
 15819: <p>I've also had good results with using the <a href="https://mchr3k.github.io/arduino-libs-manchester/" rel="nofollow">Mchr3k - Arduino Manchester Encoding</a> library with those 315mhz RF kits. It has support for ATTiny85 as well.</p>
