From: http://www.elecfreaks.com/203.html
First of all, if you have any problem, please feel free to let us kown, and the code do not use Arduino’s SPI library, but softwore imitate SPI, maybe you can modified and complete it.
The nRF24L01 module can be controlled in many ways, one of which is Arduino. We tried and tested it, then made a demo. Let’s see how it works with Arduino.
First of all, of course, you need two Arduino boards and at least two RF modules, one to transmit and the other to receive. If you don’t have, you can get them in our store in a very low cost. (Order nRF24L01 module)
If you use a standard Arduino board, you should use the Arduino board’s 3.3V pin（VDD3V3） to provide power. Beacuse the nRF24L01 module is worked at 1.9-3.6V voltage level. Please note, do not use 5V pin(VDD5V) to provide power, which may destroy it.
The Demo pins to Arduino as below:
GND – GND, VCC – 3.3V, CS – D8, CSN – D9, SCK – D10, MOSI – D11, MISO – D12, IRQ – D13
Download the code below into the TX Arduino (transmit) — This code will drive the nRF24L01 module to send out data form 0×00 to 0xFF .
Note, between the write TX_FIFO and clear RX_DR or TX_DS or MAX_RT interrupt flag, would better not serial print anything, which maybe case ACK failed.
void setup()
{
SPI_DIR = ( CE + SCK + CSN + MOSI);
SPI_DIR &=~ ( IRQ + MISO);
// attachInterrupt(1, _ISR, LOW);// interrupt enable
Serial.begin(9600);
init_io(); // Initialize IO port
unsigned char status=SPI_Read(STATUS);
Serial.print("status = ");
Serial.println(status,HEX); // read the mode’s status register, the default value should be ‘E’
Serial.println("*******************TX_Mode Start****************************");
TX_Mode(); // set TX mode
}
void loop()
{
int k = 0;
for(;;)
{
for(int i=0; i<32; i++)
tx_buf[i] = k++;
unsigned char status = SPI_Read(STATUS); // read register STATUS's value
if(status&TX_DS) // if receive data ready (TX_DS) interrupt
{
SPI_RW_Reg(FLUSH_TX,0);
SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH); // write playload to TX_FIFO
}
if(status&MAX_RT) // this is retransmit than SETUP_RETR
{
SPI_RW_Reg(FLUSH_TX,0);
SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH); // disable standy-mode
}
SPI_RW_Reg(WRITE_REG+STATUS,status); // clear RX_DR or TX_DS or MAX_RT interrupt flag
delay(1000);
}
}
Download the code below into the RX Arduino (receive) – This code will drive the nFR24L01 module to receive the data that transmit form the TX module and print it to serial port.
Note, clear RX_FIFO must bellow Read_FIFO
void setup()
{
SPI_DIR = ( CE + SCK + CSN + MOSI);
SPI_DIR &=~ ( IRQ + MISO);
// attachInterrupt(1, _ISR, LOW); // interrupt enable
Serial.begin(9600);
init_io(); // Initialize IO port
unsigned char status=SPI_Read(STATUS);
Serial.print("status = ");
Serial.println(status,HEX); // read the mode’s status register, the default value should be ‘E’
Serial.println("*****************RX_Mode start******************************R");
RX_Mode(); // set RX mode
}
void loop()
{
for(;;)
{
unsigned char status = SPI_Read(STATUS); // read register STATUS's value
if(status&RX_DR) // if receive data ready (TX_DS) interrupt
{
SPI_Read_Buf(RD_RX_PLOAD, rx_buf, TX_PLOAD_WIDTH); // read playload to rx_buf
SPI_RW_Reg(FLUSH_RX,0); // clear RX_FIFO
for(int i=0; i<32; i++)
{
Serial.print(" ");
Serial.print(rx_buf[i],HEX); // print rx_buf
}
Serial.println(" ");
}
SPI_RW_Reg(WRITE_REG+STATUS,status); // clear RX_DR/TX_DS/MAX_RT interrupt flag
delay(1000);
}
}
Now power on both Arduino , and connect the RX one to PC via USB. Open the IDE serial port monitor , change the baud rate to 9600 bps , and you can see the data that received.
If you want to change Arduino pin connecting to module , just modify the define on the NRF24L01.h .
All the project here(include API.h and NRF24L01.h)
Download nRF24L01_Demo_For_Arduino.