Some of you might be working on the robot and looking for code of the modules. And here are the source code links for your reference.
NRF24L01 based on 51 / ATMEGA32 / Arduino platform
http://www.icstation.com/ebay/IC/All%20 ... s/1388.zip
HC-SR04 Ultrasonic Module based on C51 / AVR / Arduino platform
http://www.icstation.com/ebay/IC/All%20 ... s/1389.zip