Optimized High Speed NRF24L01+ Driver Class Documenation  V1.0
TMRh20 2014 - Optimized Fork of NRF24L01+ Driver
ATTiny

ATTiny support is built into the library, so users are not required to include SPI.h in their sketches
See the included rf24ping85 example for pin info and usage

Some versions of Arduino IDE may require a patch to allow use of the full program space on ATTiny
See https://github.com/TCWORLD/ATTinyCore/tree/master/PCREL%20Patch%20for%20GCC for ATTiny patch

ATTiny board support initially added from https://github.com/jscrane/RF24

Hardware Configuration

By tong67 ( https://github.com/tong67 )

ATtiny25/45/85 Pin map with CE_PIN 3 and CSN_PIN 4

+-\/-+
NC PB5 1|o |8 Vcc --- nRF24L01 VCC, pin2 --- LED --- 5V
nRF24L01 CE, pin3 --- PB3 2| |7 PB2 --- nRF24L01 SCK, pin5
nRF24L01 CSN, pin4 --- PB4 3| |6 PB1 --- nRF24L01 MOSI, pin6
nRF24L01 GND, pin1 --- GND 4| |5 PB0 --- nRF24L01 MISO, pin7
+----+


ATtiny25/45/85 Pin map with CE_PIN 3 and CSN_PIN 3 => PB3 and PB4 are free to use for application
Circuit idea from http://nerdralph.blogspot.ca/2014/01/nrf24l01-control-with-3-attiny85-pins.html
Original RC combination was 1K/100nF. 22K/10nF combination worked better.
For best settletime delay value in RF24::csn() the timingSearch3pin.ino sketch can be used.
This configuration is enabled when CE_PIN and CSN_PIN are equal, e.g. both 3
Because CE is always high the power consumption is higher than for 5 pins solution

^^
+-\/-+ nRF24L01 CE, pin3 ------| //
PB5 1|o |8 Vcc --- nRF24L01 VCC, pin2 ------x----------x--|<|-- 5V
NC PB3 2| |7 PB2 --- nRF24L01 SCK, pin5 --|<|---x-[22k]--| LED
NC PB4 3| |6 PB1 --- nRF24L01 MOSI, pin6 1n4148 |
nRF24L01 GND, pin1 -x- GND 4| |5 PB0 --- nRF24L01 MISO, pin7 |
| +----+ |
|-----------------------------------------------||----x-- nRF24L01 CSN, pin4
10nF


ATtiny24/44/84 Pin map with CE_PIN 8 and CSN_PIN 7
Schematic provided and successfully tested by Carmine Pastore (https://github.com/Carminepz)

+-\/-+
nRF24L01 VCC, pin2 --- VCC 1|o |14 GND --- nRF24L01 GND, pin1
PB0 2| |13 AREF
PB1 3| |12 PA1
PB3 4| |11 PA2 --- nRF24L01 CE, pin3
PB2 5| |10 PA3 --- nRF24L01 CSN, pin4
PA7 6| |9 PA4 --- nRF24L01 SCK, pin5
nRF24L01 MISO, pin7 --- PA6 7| |8 PA5 --- nRF24L01 MOSI, pin6
+----+


ATtiny2313/4313 Pin map with CE_PIN 12 and CSN_PIN 13

+-\/-+
PA2 1|o |20 VCC --- nRF24L01 VCC, pin2
PD0 2| |19 PB7 --- nRF24L01 SCK, pin5
PD1 3| |18 PB6 --- nRF24L01 MOSI, pin6
PA1 4| |17 PB5 --- nRF24L01 MISO, pin7
PA0 5| |16 PB4 --- nRF24L01 CSN, pin4
PD2 6| |15 PB3 --- nRF24L01 CE, pin3
PD3 7| |14 PB2
PD4 8| |13 PB1
PD5 9| |12 PB0
nRF24L01 GND, pin1 --- GND 10| |11 PD6
+----+