I wrote a little RISC assembly program for ATtiny85 to send data over NRF24l01+
The transmitter side has a button. The receiver side has a LED. When the button is pressed on the one side, the LED is switched on, on the other side.
To program the ATtinys I used AVR Studio 7.0, avrdude.exe, and an Arduino UNO as ISP.
I chose to connect CE to VDD. I don't use the reset pin.
-C"C:\Program Files (x86)\arduino\hardware\tools\avr\etc\avrdude.conf" -v -pt85 -carduino -b19200 -PCOM3 -U lfuse:w:0x62:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m -Uflash:w:"$(ProjectDir)Debug$(TargetName).hex":i
Transmission power can influence the packet loss rate. When the RF modules are close together, choose the minimal power (-18dB).