Ive had some luck with this tutorial:http://nerdralph.blogspot.ca/2014/01/nrf24l01-control-with-3-attiny85-pins.html
I had discussed this exact project with a buddy, Jack Christensen who supplied also a modified schematic of the one mentioned on Ralphs blog.
Please post back with your progress/updates! It takes a bit of messing with the header files. Here is a list of steps I took following Ralphs blog and Jack's schematic:Proper Attiny85 library installation for nrf24l01
download the latest version, Arduino 1.5. Extract, and drag the “avr” folder (found inside the “tiny” folder) into a newly created folder located in the sketch folder called “hardware”.
the avr folder should be the parent folder of the at tiny cores/etc due to the Arduino IDE directory tree hierarchy.
NOTE: you will need to rename the txt file called “Prospective Boards.txt” to simply “boards.txt” within the “avr” folder
A proper installation should indicate the attiny boards available to select in tools.
download the “door monitor” file containing libraries needed : https://github.com/samuelclay/doormonitor
the only folders of interests are within the “mirf “ folder are the “Mirf” and the “SPI85” folders, that I dragged within the main libraries folder (not the sketch libraries folder)
according to http://nerdralph.blogspot.com/2014/01/nrf24l01-control-with-3-attiny85-pins.html
, modify the Mirf.cpp as follows:
PORTB |= (1<<PINB2); // SCK->CSN HIGH
delayMicroseconds(64); // allow csn to settle
PORTB &= ~(1<<PINB2); // SCK->CSN LOW
delayMicroseconds(8); // allow csn to settle
unmodified, everything compiled. when i incorporated Ralphs suggestion: