File content as of revision 2:653be5496b69:

#include "mbed.h"
#include "nRF24L01P.h"

Serial pc(USBTX, USBRX); // tx, rx

nRF24L01P my_nrf24l01p(p5, p6, p7, p8, p9, p10);    // mosi, miso, sck, csn, ce, irq

DigitalOut myled1(LED1);
DigitalOut myled2(LED2);

Timer t;

int main() {

// The nRF24L01+ supports transfers from 1 to 32 bytes, but Sparkfun's
//  "Nordic Serial Interface Board" (http://www.sparkfun.com/products/9019)
//  only handles 4 byte transfers in the ATMega code.
#define TRANSFER_SIZE   4

    char txData[TRANSFER_SIZE], rxData[TRANSFER_SIZE];
    int txDataCnt = 0;
    int rxDataCnt = 0;
    int tmpDataCnt = 0;
    char tmpData[TRANSFER_SIZE+1];

    my_nrf24l01p.powerUp();

    // Display the (default) setup of the nRF24L01+ chip
    pc.printf( "nRF24L01+ Frequency    : %d MHz\r\n",  my_nrf24l01p.getRfFrequency() );
    pc.printf( "nRF24L01+ Output power : %d dBm\r\n",  my_nrf24l01p.getRfOutputPower() );
    pc.printf( "nRF24L01+ Data Rate    : %d kbps\r\n", my_nrf24l01p.getAirDataRate() );
    pc.printf( "nRF24L01+ TX Address   : 0x%010llX\r\n", my_nrf24l01p.getTxAddress() );
    pc.printf( "nRF24L01+ RX Address   : 0x%010llX\r\n", my_nrf24l01p.getRxAddress() );

    pc.printf( "Type keys to test transfers:\r\n  (transfers are grouped into %d characters)\r\n", TRANSFER_SIZE );

    my_nrf24l01p.setTransferSize( TRANSFER_SIZE );

    my_nrf24l01p.setReceiveMode();
    my_nrf24l01p.enable();

    while (1) {

        // If we've received anything over the host serial link...
        if ( pc.readable() ) {

            // ...add it to the transmit buffer
            txData[txDataCnt++] = pc.getc();

            // If the transmit buffer is full
            if ( txDataCnt >= sizeof( txData ) ) {

                t.start();
                
                // Send the transmitbuffer via the nRF24L01+
                my_nrf24l01p.write( NRF24L01P_PIPE_P0, txData, txDataCnt );
                
                txDataCnt = 0;
            }

            // Toggle LED1 (to help debug Host -> nRF24L01+ communication)
            myled1 = !myled1;
        }

        // If we've received anything in the nRF24L01+...
        if ( my_nrf24l01p.readable() ) {
                
            // ...read the data into the receive buffer
            rxDataCnt = my_nrf24l01p.read( NRF24L01P_PIPE_P0, rxData, sizeof( rxData ) );

            // Display the receive buffer contents via the host serial link
            for ( int i = 0; rxDataCnt > 0; rxDataCnt--, i++ ) {
            
                pc.putc( rxData[i] );
                tmpData[tmpDataCnt++] = rxData[i]; 
            }
            
            if ( tmpDataCnt >= TRANSFER_SIZE ) {
                tmpData[TRANSFER_SIZE] = '\0';
                //pc.printf( "Received data : %s \r\n", tmpData);
                if (strcmp(tmpData, "ackn"))
                {
                    tmpData[0] = 'a';
                    tmpData[1] = 'c';
                    tmpData[2] = 'k';
                    tmpData[3] = 'n';
                    //pc.printf( "Sending data : %s \r\n", "ackn");
                    my_nrf24l01p.write( NRF24L01P_PIPE_P0, tmpData, tmpDataCnt );  
                }
                else
                {
                    t.stop();
                    pc.printf("\r\nThe time taken was %f seconds \r\n", t.read());
                    t.reset();
                }
                
                 
                tmpDataCnt = 0;   
            }

            // Toggle LED2 (to help debug nRF24L01+ -> Host communication)
            myled2 = !myled2;
        }
    }
}