File content as of revision 19:6f01eb6f4163:

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

#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 15
#define MAX_BUFFER_SIZE 255
#define BUFFER_SIZE MAX_BUFFER_SIZE

#define DATA_PROTOCOL_BEGIN '$'
#define DATA_PROTOCOL_TOKEN ','
#define DATA_PROTOCOL_TOKEN_ ","
#define DATA_PROTOCOL_END   '*'
#define DATA_PROTOCOL_END_  "*"

#define NRF_TRANSMIT    1
#define NRF_RECEIVE     2

#define NRF_RETRIAL_MAX 5

nRF24L01P nrf(spi_MOSI, spi_MISO, spi_SCK, nrf_CSN, nrf_CE, spi_IRQ);    // mosi, miso, sck, csn, ce, irq
Serial pc(USBTX, USBRX);
PwmOut buzzer(D5);

uint64_t txAddr = 0xDEADBEEF0F;
uint64_t rxAddr = 0xDEADBEEF00;

typedef struct {
    int bot_id;
    int cmd_id;
    int lspeed;
    int rspeed;
} payload_t;

void beepStart();
void endBeep();
void initNRF(int mode, int msg_len);
void dumpRFInfo();
int readSerialUntil(char *buffer, unsigned int buf_len, char terminator);
char* inspectData(char *buffer, int buf_len);
payload_t* getPayload(char* raw_data);
int transmitCmd(payload_t *p);

int main()
{
    char buffer[BUFFER_SIZE];
    beepStart();
    pc.baud(115200);
    printf("I'm Master\r\n");
    initNRF(NRF_TRANSMIT, TRANSFER_SIZE);
//    dumpRFInfo();

    memset(buffer, NULL, BUFFER_SIZE);

    while(1) {
        int result = readSerialUntil(buffer, BUFFER_SIZE, DATA_PROTOCOL_END);
        if(result>0) {
            char *data = inspectData(buffer, BUFFER_SIZE);
            if(*data == DATA_PROTOCOL_BEGIN) {
                payload_t *payload = getPayload(data);
                printf("Sent - BotID:%d, CmdID:%d, LSpeed:%d, RSpeed:%d\r\n", payload->bot_id, payload->cmd_id, payload->lspeed, payload->rspeed);
                int n = transmitCmd(payload);
                free(data);
                free(payload);
            }
        }
    }
}

void constructString(char *txData, payload_t *p)
{
    *(txData+0) = '$';
    *(txData+1) = p->bot_id/10+'0';
    *(txData+2) = p->bot_id%10+'0';
    *(txData+3) = p->cmd_id/10000+'0';
    *(txData+4) = p->cmd_id/1000%10+'0';
    *(txData+5) = p->cmd_id/100%10+'0';
    *(txData+6) = p->cmd_id/10%10+'0';
    *(txData+7) = p->cmd_id%10+'0';
    *(txData+8) = p->lspeed>0?'+':'-';
    *(txData+9) = abs(p->lspeed)/10+'0';
    *(txData+10) = abs(p->lspeed)%10+'0';
    *(txData+11) = p->rspeed>0?'+':'-';
    *(txData+12) = abs(p->rspeed)/10+'0';
    *(txData+13) = abs(p->rspeed)%10+'0';
    *(txData+14) = '\0';
}

int transmitCmd(payload_t *p)
{
    int trial = 0;
    int rxDataCnt=0;
    char rxData[MAX_BUFFER_SIZE];
    char buf[TRANSFER_SIZE];
    
    while(trial<NRF_RETRIAL_MAX) {
        initNRF(NRF_TRANSMIT, TRANSFER_SIZE);
        constructString(buf, p);

        nrf.write(NRF24L01P_PIPE_P0, buf, TRANSFER_SIZE);
        initNRF(NRF_RECEIVE, TRANSFER_SIZE);
        wait(0.01);
        rxDataCnt = nrf.read( NRF24L01P_PIPE_P0, rxData, TRANSFER_SIZE);
        if(rxDataCnt>0) {
            return 1;
        }
        trial++;
    }
    printf("No Reply from Bot..\r\n");
    return 0;
}

payload_t* getPayload(char *data)
{
    int n = strlen(data);
    char _data[n+1];
    strcpy(_data, data);
    payload_t *p = (payload_t*)malloc(sizeof(payload_t));
    p->bot_id = atoi(strtok(data+1, DATA_PROTOCOL_TOKEN_));
    p->cmd_id = atoi(strtok(NULL, DATA_PROTOCOL_TOKEN_));
    p->lspeed = atoi(strtok(NULL, DATA_PROTOCOL_TOKEN_));
    p->rspeed = atoi(strtok(NULL, DATA_PROTOCOL_END_));
    return p;
}

char* inspectData(char *buffer, int buf_len)
{
    int start, end;
    for(int i=0; buffer[i-1]!=DATA_PROTOCOL_BEGIN; i++) {
        start = i;
        if(i==buf_len) return 0;
    }
    for(int i=start+1; buffer[i-1]!=DATA_PROTOCOL_END; i++) {
        end = i;
        if(i==buf_len) return 0;
    }
    int data_len = end-start+1;
    char *str = (char*)malloc(sizeof(char)*(data_len+1));
    memset(str, NULL, data_len+1);
    for(int i=0; i<data_len; i++) {
        *(str+i) = buffer[start+i];

        if(buffer[start+i]==DATA_PROTOCOL_BEGIN || buffer[start+i]==DATA_PROTOCOL_TOKEN || buffer[start+i]==DATA_PROTOCOL_END
                || (buffer[start+i]>='0'&&buffer[start+i]<='9') || buffer[start+i]=='+' || buffer[start+i]=='-') {
            continue;
        } else {
            //pc.putc(buffer[start+i]);
            free(str);
            return 0;
        }
    }
    return str;
}

int readSerialUntil(char *buffer, unsigned int buf_len, char term)
{
    int n=0;
    char *str = (char*)malloc(sizeof(char)*buf_len);
    memset(str, NULL, buf_len);
    Timer t;
    t.start();
    int begin = t.read_ms();
    while(t.read_ms()-begin < 100) {
        if(pc.readable()) {
            char inByte=pc.getc();
            *(str+n)=inByte;
            n++;
            if(inByte == term) {
                strcpy(buffer, str);
                free(str);
                return n;
            }
            if(n>buf_len) {
                free(str);
                return -1;
            }
        }
    }
    free(str);
    return 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 mode, int msg_len)
{
#ifndef NRF_FIRST_INIT
#define NRF_FIRST_INIT
    nrf.setTxAddress(txAddr);
    nrf.setRxAddress(rxAddr);
    nrf.powerUp();
#endif
    switch(mode) {
        case NRF_TRANSMIT:
            nrf.setTransferSize(msg_len);
            nrf.setTransmitMode();
            nrf.enable();
            break;
        case NRF_RECEIVE:
            nrf.setTransferSize(msg_len);
            nrf.setReceiveMode();
            nrf.enable();
            break;
        default:
            printf("Invalid NRF Mode\r\n");
    }
}
/*
void getPayload(int id, unsigned int count, int lspeed, int rspeed, char* txData)
{
    *(txData+0) = '$';
    *(txData+1) = id/10+'0';
    *(txData+2) = id%10+'0';
    *(txData+3) = count/10000+'0';
    *(txData+4) = count/1000%10+'0';
    *(txData+5) = count/100%10+'0';
    *(txData+6) = count/10%10+'0';
    *(txData+7) = count%10+'0';
    *(txData+8) = lspeed>0?'+':'-';
    *(txData+9) = abs(lspeed)/10+'0';
    *(txData+10) = abs(lspeed)%10+'0';
    *(txData+11) = rspeed>0?'+':'-';
    *(txData+12) = abs(rspeed)/10+'0';
    *(txData+13) = abs(rspeed)%10+'0';
    *(txData+14) = '\0';
}
xxyyyyyabbcddn

14 chars

xx: robot_id
yyyyy: packet_id
a: sign of lspeed
bb: lspeed
c: sign of rspeed
dd: rspeed
n: NULL 0

0100001+30+30
*/