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All things pertaining to wireless and RF links
By AgroMe

I wonder if the ATtiny85 is enough to drive an RFM22B-S2, not sure if this is the best combination for what we are trying to achieve.

We are designing an irrigation system that has capacitive moisture sensors in each plant that are usually wired but we are looking at eliminating the wiring in a very inexpensive way. The sensor has a 0-5V output and we think we could leverage the 8 bit ADC of the RFM22B-S2 driven by an ATtiny85 and keep everything very low cost and battery efficient.

Not sure if the SPI library is easy to implement on the ATtiny85 with the Arduino IDE etc. etc. but the reviews suggest the ATtiny85 is a pretty amazing little chip, but I couldn't find any examples using SPI, only I2C and the RFM22B-S2 is SPI. Maybe another radio would work too... we need to have an ID so that we know which data is coming from which plant. The RFM22B-S2 seems ideal for this application because it's very low cost.

I guess the main question is: IS the ATtiny85 is able to drive the RFM22B-S2 via SPI and if this could be programmed using the Arduino IDE and the SparkFun AVR Programmer (11801).

Any suggestions, comments or ideas or pointers to similar implementation examples greatly appreciated!