msprf24_rxtx_ike

Simple RX/TX example from ike -- uses USCI_A SPI port on the MSP430G2553, flip-flops the Red and Green LEDs back and forth; TX side signals Green for successful transmission, Red for unsuccessful transmission, and the RX side reflects the contents of the data packet sent by the TX; it should show the red & green LEDs alternating.

This is not compatible with my nRF24L01+ boosterpack because that is hardwired to use USCI_B; this requires USCI_A so you may need to use jumper wires to hook up the transceiver.

TX example:

#include <msp430.h>
#include "msprf24.h"
#include "nrf_userconfig.h"
#include "stdint.h"

volatile unsigned int user;

void main()
{
    char addr[5];
    char buf[32];

    WDTCTL = WDTHOLD | WDTPW;
    DCOCTL = CALDCO_16MHZ;
    BCSCTL1 = CALBC1_16MHZ;
    BCSCTL2 = DIVS_1;  // SMCLK = DCOCLK/2
    // SPI (USCI) uses SMCLK, prefer SMCLK < 10MHz (SPI speed limit for nRF24 = 10MHz)

    // Red, Green LED used for status
    P1DIR |= 0x41;
    P1OUT &= ~0x41;

    user = 0xFE;  // this is just used for testing, examined via debugger, it can be ignored

    /* Initial values for nRF24L01+ library config variables */
    rf_crc = RF24_EN_CRC | RF24_CRCO; // CRC enabled, 16-bit
    rf_addr_width      = 5;
    rf_speed_power     = RF24_SPEED_1MBPS | RF24_POWER_0DBM;
    rf_channel     = 120;

    msprf24_init();  // All RX pipes closed by default
    msprf24_set_pipe_packetsize(0, 32);
    msprf24_open_pipe(0, 1);  // Open pipe#0 with Enhanced ShockBurst enabled for receiving Auto-ACKs

    // Transmit to 'rad01' (0x72 0x61 0x64 0x30 0x31)
    msprf24_standby();
    user = msprf24_current_state();
    addr[0] = 0xDE; addr[1] = 0xAD; addr[2] = 0xBE; addr[3] = 0xEF; addr[4] = 0x00;
    w_tx_addr(addr);
    w_rx_addr(0, addr);  // Pipe 0 receives auto-ack's, autoacks are sent back to the TX addr so the PTX node
                     // needs to listen to the TX addr on pipe#0 to receive them.

    while(1){
        __delay_cycles(800000);
        if(buf[0]=='0'){buf[0] = '1';buf[1] = '0';}
        else {buf[0] = '0';buf[1] = '1';}
        w_tx_payload(32, buf);
        msprf24_activate_tx();
        LPM4;

        if (rf_irq & RF24_IRQ_FLAGGED) {
            msprf24_get_irq_reason();
            if (rf_irq & RF24_IRQ_TX){
                P1OUT &= ~BIT0; // Red LED off
                P1OUT |= 0x40;  // Green LED on
            }
            if (rf_irq & RF24_IRQ_TXFAILED){
                P1OUT &= ~BIT6; // Green LED off
                P1OUT |= BIT0;  // Red LED on
            }

            msprf24_irq_clear(rf_irq);
            user = msprf24_get_last_retransmits();
        }
    }
}

Example nrf_userconfig.h file for TX (shed the comments at the top for brevity):

#ifndef _NRF_USERCONFIG_H
#define _NRF_USERCONFIG_H

/* CPU clock cycles for the specified amounts of time--accurate minimum delays
 * required for reliable operation of the nRF24L01+'s state machine.
 */
/* Settings for 1MHz MCLK.
#define DELAY_CYCLES_5MS       5000
#define DELAY_CYCLES_130US     130
#define DELAY_CYCLES_15US      15
 */

/* Settings for 8MHz MCLK.
#define DELAY_CYCLES_5MS       40000
#define DELAY_CYCLES_130US     1040
#define DELAY_CYCLES_15US      120
 */

/* Settings for 16MHz MCLK */
#define DELAY_CYCLES_5MS       80000
#define DELAY_CYCLES_130US     2080
#define DELAY_CYCLES_15US      240

/* SPI port--Select which USCI port we're using.
 * Applies only to USCI devices.  USI users can keep these
 * commented out.
 */
#define SPI_DRIVER_USCI_A 1
//#define SPI_DRIVER_USCI_B 1


/* Operational pins -- IRQ, CE, CSN (SPI chip-select)
 */

/* IRQ */
#define nrfIRQport 2
#define nrfIRQpin BIT2

/* CSN SPI chip-select */
#define nrfCSNport 2
#define nrfCSNportout P2OUT
#define nrfCSNpin BIT1

/* CE Chip-Enable (used to put RF transceiver on-air for RX or TX) */
#define nrfCEport 2
#define nrfCEportout P2OUT
#define nrfCEpin BIT0

#endif

RX example:

#include <msp430.h>
#include "msprf24.h"
#include "nrf_userconfig.h"
#include "stdint.h"

volatile unsigned int user;

void main()
{
    char addr[5];
    char buf[32];

    WDTCTL = WDTHOLD | WDTPW;
    DCOCTL = CALDCO_16MHZ;
    BCSCTL1 = CALBC1_16MHZ;
    BCSCTL2 = DIVS_1;  // SMCLK = DCOCLK/2
    // SPI (USCI) uses SMCLK, prefer SMCLK < 10MHz (SPI speed limit for nRF24 = 10MHz)

    // Red LED will be our output
    P1DIR |= BIT0+BIT6;
    P1OUT &= ~(BIT0+BIT6);

    user = 0xFE;

    /* Initial values for nRF24L01+ library config variables */
    rf_crc = RF24_EN_CRC | RF24_CRCO; // CRC enabled, 16-bit
    rf_addr_width      = 5;
    rf_speed_power     = RF24_SPEED_1MBPS | RF24_POWER_0DBM;
    rf_channel     = 120;

    msprf24_init();
    msprf24_set_pipe_packetsize(0, 32);
    msprf24_open_pipe(0, 1);  // Open pipe#0 with Enhanced ShockBurst

    // Set our RX address
    addr[0] = 0xDE; addr[1] = 0xAD; addr[2] = 0xBE; addr[3] = 0xEF; addr[4] = 0x00;
    w_rx_addr(0, addr);

    // Receive mode
    if (!(RF24_QUEUE_RXEMPTY & msprf24_queue_state())) {
        flush_rx();
    }
    msprf24_activate_rx();
    LPM4;

    while (1) {
        if (rf_irq & RF24_IRQ_FLAGGED) {
            msprf24_get_irq_reason();
        }
        if (rf_irq & RF24_IRQ_RX) {
            r_rx_payload(32, buf);
            msprf24_irq_clear(RF24_IRQ_RX);
            user = buf[0];

            if (buf[0] == '0')
                P1OUT &= ~BIT0;
            if (buf[0] == '1')
                P1OUT |= BIT0;
            if (buf[1] == '0')
                P1OUT &= ~BIT6;
            if (buf[1] == '1')
                P1OUT |= BIT6;

        } else {
            user = 0xFF;
        }
        LPM4;
    }
}

The nrf_userconfig.h used by the RX code is the same as that used by the TX code.