File content as of revision 11:1b56bb8ccd04:

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

#define PING 1
#define PONG 2

#define ROLE PONG
#define ID 0

#define nrf_CE      D2
#define nrf_CSN     A3
#define spi_SCK     D13
#define spi_MOSI    D11
#define spi_MISO    D12
#define spi_IRQ     D4

#define TRANSFER_SIZE 14

nRF24L01P nrf(spi_MOSI, spi_MISO, spi_SCK, nrf_CSN, nrf_CE, spi_IRQ);    // mosi, miso, sck, csn, ce, irq

Serial pc(USBTX, USBRX);
Serial lidar(D1, D0);

PwmOut motor_RA(D9);
PwmOut motor_RB(D10);
PwmOut motor_LA(D3);
PwmOut motor_LB(D6);
PwmOut led_B(A5);
PwmOut led_G(A2);
PwmOut led_R(A1);
PwmOut buzzer(D5);
AnalogIn batteryCheck(A0);

void beepStart();
void endBeep();
void initNRF(int role);
void dumpRFInfo();
void turnWheel(int rspd, int lspd);
void getPayload(int id, unsigned int count, int lspeed, int rspeed, char* txData);


int main() {
    int role = ROLE;
    int id=0;
    char txData[TRANSFER_SIZE];
    int txDataCnt = 0;
    char rxData[TRANSFER_SIZE];
    int rxDataCnt = 0;
    
    beepStart();
    pc.baud(115200);
    initNRF(role);
    dumpRFInfo();
    
    while(1) {
        if(role == PING) {
            int id = 1;
            int lspeed=-40;
            int rspeed=50;
            //printf("transmitting\r\n");
            txDataCnt++;
            getPayload(id, txDataCnt, lspeed, rspeed, txData);
            //char txData_[] = "123456789ABCD";
            pc.printf("PING:%s\r\n", txData);
            nrf.write(NRF24L01P_PIPE_P0, txData, TRANSFER_SIZE);
            wait(0.2);
        }
        else if(role == PONG) {
            if ( nrf.readable() ) {
                rxDataCnt = nrf.read( NRF24L01P_PIPE_P0, rxData, TRANSFER_SIZE);
                printf("%s\r\n", rxData);
                int rspd = (rxData[8]-'0')*10+(rxData[9]-'0');
                int lspd = (rxData[11]-'0')*10+(rxData[12]-'0');
                if(rxData[7]=='-')
                    rspd = -rspd;
                if(rxData[10]=='-')
                    lspd = -lspd;
                turnWheel(rspd, lspd);
                printf("%d, %d\r\n", rspd,lspd);
            }
        }
    }
}

void turnWheel(int rspd, int lspd)
{
    if(rspd>0) {
        motor_RA.write((float)rspd/100);
        motor_RB = 0;
    } else {
        rspd=-rspd;
        motor_RB.write((float)rspd/100);
        motor_RA = 0;
    }
    if(lspd>0) {
        motor_LA.write((float)lspd/100);
        motor_LB = 0;
    } else {
        lspd = -lspd;
        motor_LB.write((float)lspd/100);
        motor_LA = 0;
    }
}

void dumpRFInfo()
{
    printf( "nRF24L01+ Frequency    : %d MHz\r\n",  nrf.getRfFrequency() );
    printf( "nRF24L01+ Output power : %d dBm\r\n",  nrf.getRfOutputPower() );
    printf( "nRF24L01+ Data Rate    : %d kbps\r\n", nrf.getAirDataRate() );
    printf( "nRF24L01+ TX Address   : 0x%010llX\r\n", nrf.getTxAddress() );
    printf( "nRF24L01+ RX Address   : 0x%010llX\r\n", nrf.getRxAddress() );
}

void initNRF(int role)
{
    if(role == PING) {
        nrf.setTxAddress(0xDEADBEEF0F);
        nrf.powerUp();
        nrf.setTransferSize( TRANSFER_SIZE );
        nrf.setTransmitMode();
        nrf.enable();
    } else {
        nrf.setRxAddress(0xDEADBEEF0F);
        nrf.powerUp();
        nrf.setTransferSize( TRANSFER_SIZE );
        nrf.setReceiveMode();
        nrf.enable();
    }
}

void getPayload(int id, unsigned int count, int lspeed, int rspeed, char* txData)
{
    *(txData+0) = id/10+'0';
    *(txData+1) = id%10+'0';
    *(txData+2) = count/10000+'0';
    *(txData+3) = count/1000%10+'0';
    *(txData+4) = count/100%10+'0';
    *(txData+5) = count/10%10+'0';
    *(txData+6) = count%10+'0';
    *(txData+7) = lspeed>0?'+':'-';
    *(txData+8) = abs(lspeed)/10+'0';
    *(txData+9) = abs(lspeed)%10+'0';
    *(txData+10) = rspeed>0?'+':'-';
    *(txData+11) = abs(rspeed)/10+'0';
    *(txData+12) = abs(rspeed)%10+'0';
    *(txData+13) = '\0';
}