TinyBME - ATTiny85 + NRF24l01 + BME280/I2C

  • Hi.

    Just published current status of my work on ATTiny85 node with NRF24L01 and BME280 (4 pin I2C version) and want to share it here.


    TLDR - It works! ๐Ÿ™‚

    It is based on fabyte's work and couple of other resources.

    • NRF24L01 works from 3 pins - MOSI/MISO/SCK, keeping CE constantly high and multiplexing CE over SCK.
    • BME280 is connected via pins 3 and 4 on ATTiny85 and communicates over SoftWire
    • It works just fine from 18650 battery. Prolly should work from CR2032 too. Didn't test current consumption (yet).
    • Right now code is just 92 bytes under 8K limit - no space for conversions of units - I'm doing it at HASS.
    • There is neither free pins nor flash to report the battery status. Prolly some kind alarm on lost heartbeats is much as could be done in this situation.

    In general I'm open for suggestions and improvement ideas.


  • Great achievement, congratulations ๐Ÿ‘ ๐Ÿ™‚

    I like that you also tried Nerd Ralph's 3-Pin configuration and got it to work. I tried it once but somehow it didn't connect to the radio, so discarded this idea. Also I thought it might be cheaper (from a memory point of view), just to use one bus. Nice work on stuffing all this in 8K ๐Ÿ™‚

    It would be great if you reported in a couple of weeks how stable it's running. Did you have a chance to measure the power consumption of the hole system?

  • I was attracted to the idea of having a wireless hum/temp sensor and so I built this. I prototyped it on a breadboard, and I also soldered it on a PCB. I extended the antenna with a 8.3 cm wire.

    But I can't get it to work stable. Sometimes it works for many hours and sometimes only for one hour. And then it just hangs. A reset of the at85 sometimes helps, but most of the times I need to power it off and on again.

    I need it to work reliably for several weeks. Any suggestions ?

Log in to reply

Suggested Topics

  • 4
  • 4
  • 2
  • 1
  • 1
  • 17
  • 42
  • 6