https://github.com/sunsided/avr-rfm12

RFM12B transceiver controller implementation for AVR
https://github.com/sunsided/avr-rfm12

atmega328p avr cplusplus embedded rfm12b transmission

Last synced: 13 days ago
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RFM12B transceiver controller implementation for AVR

• Host: GitHub
• URL: https://github.com/sunsided/avr-rfm12
• Owner: sunsided
• Created: 2013-06-15T23:50:57.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2013-09-09T18:25:25.000Z (over 11 years ago)
• Last Synced: 2024-11-09T08:25:48.345Z (about 2 months ago)
• Topics: atmega328p, avr, cplusplus, embedded, rfm12b, transmission
• Language: C++
• Homepage:
• Size: 1.91 MB
• Stars: 3
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# RFM12 on ATmega328P

## A wireless sensor network using the RFM12 transceiver

An AVR implementation in progress.

### Configuration

* ATmega328P running at 16MHz (Arduino Nano + Duemilanove)

* SPI configured in mode 0 (`CPOL=0`, `CPHA=0`) with prescaler 16 (`SPR1=0`, `SPR0=1`, `SPI2X=0`), resulting in 1MHz SPI speed.

  According to the data sheet, SPI rate during FIFO access must be smaller than 2.5MHz with the default 10MHz oscillator in place:

  > Note: During FIFO access fSCK cannot be higher than fref /4, where f ref is the crystal oscillator frequency. 

  A substantially lower SPI rate (i.e. lower than transmit frequency) results in buffer underruns on the transmitter side (`RGUR` in Status Register), obviously.

### The wires.

Wiring is basically as follows, although I eventually decided to invest in one of JeeLabs' [RFM12B breakout](http://jeelabs.com/products/rfm12b-board) boards.



  



### ... and something visual.

From an early demo, leaving the power amplifier enabled for a second before and after transmission.



  



Later, the `47`th transmission of `HOLYCOW` prefixed by magic pattern `0x01020304` (payload size `8`).