File content as of revision 5:8d2188479eec:

#include "mbed.h"
#include "nRF24L01P.h"
#include "LCD_DISCO_L476VG.h"

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

nRF24L01P my_nrf24l01p(PE_15, PE_14, PE_13, PE_12, PE_10, PE_11);    // mosi, miso, sck, csn, ce, irq

DigitalOut myled1(LED1);
DigitalOut myled2(LED2);
LCD_DISCO_L476VG lcd;

void channelChangeMode (void)
{
    char stayInWhile = 1;
    char receivedChannelCharacter;
    int rf_channel = 2400;
    pc.printf("Channel menu\n\r");
    pc.printf("select channel\n\r");
    while(stayInWhile)
    {
        pc.printf("waiting for Channel\n\r");
         if ( pc.readable() ) 
         {
            
            receivedChannelCharacter = pc.getc();

            if (receivedChannelCharacter >= '1' && receivedChannelCharacter <= '9') // if received 0 through 9 load transmit buffer
k            {
                pc.printf("received valid number\n\r");
                receivedChannelCharacter = receivedChannelCharacter - 0x30;
                rf_channel = rf_channel + receivedChannelCharacter; 
                pc.printf("new channel, %d\n\r", rf_channel);
                my_nrf24l01p.setRfFrequency(rf_channel);
                wait(1);
                pc.printf( "nRF24L01+ Frequency    : %d MHz\r\n",  my_nrf24l01p.getRfFrequency() );
                stayInWhile = 0; 
            }
            else
            {
                pc.printf(" invalid number\n\r");
            }
        }
        wait(1);
    }
    pc.printf("exiting  Channel change mode\n\r");
    
}

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;
    char receivedTerminalCharacter;
    
    uint32_t temp = 0;
    uint8_t stemp[7] = {0};
    //uint8_t title[] = "      DISCOVERY STM32L476";
    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();
    
printf("Hello\n");
    //led_green = 1;
    lcd.Clear();
    lcd.DisplayString((uint8_t *)"HELLO");
    wait(5);
      lcd.Clear();
      
    while (1) {

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

            if (receivedTerminalCharacter >= '0' && receivedTerminalCharacter <= '9') // if received 0 through 9 load transmit buffer
            {
                pc.printf("Loading TX buffer");
                // ...add it to the transmit buffer
                txData[txDataCnt++] = pc.getc();


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

                    // 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;
                }
            }
            
            else if (receivedTerminalCharacter == 'h')
            {
                 pc.printf("Radio help menu\n\r");
                 pc.printf("Press c for channel: \n\r");
                 pc.printf("Press t for TX Power: \n\r");
                 pc.printf("Press d for datarate: \n\r");
            }
            else if (receivedTerminalCharacter == 'c')
            {
                
                channelChangeMode();
                
            }
                
        }

        // 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] );
                
            }
                lcd.Clear();
                lcd.DisplayString((uint8_t *)"REC");
                wait(5);
                lcd.Clear();
}
    
   
    
   // printf("Scroll sequence\n");
    //led_green = 0;
    //lcd.Clear();
   
            // Toggle LED2 (to help debug nRF24L01+ -> Host communication)
            myled2 = !myled2;
        }
    }