51 MCU nrf24l01 transceiver

Pin Diagram

Pin 1: GND, ground terminal; Pin 2: VCC, 1.9V~3.6V

Pin 3: CE, NRF24L01 mode control terminal

Pin 4: CSN, chip select signal

Pin 5: SCK, SPI clock input

Pin 6: MOSI, SPI data input

Pin 7: MISO, SPI data output

Pin 8: IRQ, interrupt output terminal, low level enable, that is, interrupt output low level

Do not exceed 3.6V for the power supply, otherwise the chip may be damaged.

For port pins, they can withstand 5V, that is, they can be connected to TTL ports

Sending Side

#include

#define uchar unsigned char

#define TX_ADR_WIDTH 5 // 5-byte width of the transmit/receive address

#define TX_PLOAD_WIDTH 4 // Data channel effective data width

uchar code TX_ADDRESS[TX_ADR_WIDTH] = {0x34,0x43,0x10,0x10,0x01}; // Define a static send address

uchar RX_BUF[TX_PLOAD_WIDTH];

uchar TX_BUF[TX_PLOAD_WIDTH];

uchar flag;

float DATA = 0x01;

float bdata sta;

sbit RX_DR = sta^6;

sbit TX_DS = sta^5;

sbit MAX_RT = sta^4;

sbit CE = P1^5;

sbit CSN= P1^4;

sbit SCK= P1^3;

sbit MOSI= P1^2;

sbit MISO= P1^1;

sbit IRQ = P1^0;

// SPI(nRF24L01) commands

#define READ_REG    0x00  // Define read command to register

#define WRITE_REG   0x20  // Define write command to register

#define RD_RX_PLOAD 0x61  // Define RX payload register address

#define WR_TX_PLOAD 0xA0  // Define TX payload register address

#define FLUSH_TX    0xE1  // Define flush TX register command

#define FLUSH_RX    0xE2  // Define flush RX register command

#define REUSE_TX_PL 0xE3  // Define reuse TX payload register command

#define NOP         0xFF  // Define No Operation, might be used to read status register

// SPI(nRF24L01) registers(addresses)

#define CONFIG      0x00  // 'Config' register address

#define EN_AA       0x01  // 'Enable Auto Acknowledgment' register address

#define EN_RXADDR   0x02  // 'Enabled RX addresses' register address

#define SETUP_AW    0x03  // 'Setup address width' register address

#define SETUP_RETR  0x04  // 'Setup Auto. Retrans' register address

#define RF_CH       0x05  // 'RF channel' register address

#define RF_SETUP    0x06  // 'RF setup' register address

#define STATUS      0x07  // 'Status' register address

#define OBSERVE_TX  0x08  // 'Observe TX' register address

#define CD          0x09  // 'Carrier Detect' register address

#define RX_ADDR_P0  0x0A  // 'RX address pipe0' register address

#define RX_ADDR_P1  0x0B  // 'RX address pipe1' register address

#define RX_ADDR_P2  0x0C  // 'RX address pipe2' register address

#define RX_ADDR_P3  0x0D  // 'RX address pipe3' register address

#define RX_ADDR_P4  0x0E  // 'RX address pipe4' register address

#define RX_ADDR_P5  0x0F  // 'RX address pipe5' register address

#define TX_ADDR     0x10  // 'TX address' register address

#define RX_PW_P0    0x11  // 'RX payload width, pipe0' register address

#define RX_PW_P1    0x12  // 'RX payload width, pipe1' register address

#define RX_PW_P2    0x13  // 'RX payload width, pipe2' register address

#define RX_PW_P3    0x14  // 'RX payload width, pipe3' register address

#define RX_PW_P4    0x15  // 'RX payload width, pipe4' register address

#define RX_PW_P5    0x16  // 'RX payload width, pipe5' register address

#define FIFO_STATUS 0x17  // 'FIFO Status Register' register address

/**************************************************

Function: init_io()

describe:

    Initialize IO

/**************************************************/

void init_io(void)

{

    CE = 0; // Standby

    CSN = 1; // SPI disabled

    SCK = 0; // SPI clock low

    IRQ = 1; // Interrupt reset

    LED = 1; // Turn off the indicator light

}

/**************************************************/

/**************************************************

Function: delay_ms()

describe:

    Delay x milliseconds

/**************************************************/

void delay_ms(uchar x)

{

    flying i, j;

    i = 0;

    for(i=0; i    {

       j = 250;

       while(--j);

       j = 250;

       while(--j);

    }

}

/**************************************************/

/**************************************************

Function: SPI_RW()

describe:

    According to the SPI protocol, write one byte of data to nRF24L01 and

    Read one byte

/**************************************************/

volatile SPI_RW(volatile byte)

{

    flying i;

       for(i=0; i<8; i++) // loop 8 times

       {

           MOSI = (byte & 0x80); // byte highest bit is output to MOSI

           byte <<= 1; // shift the lower bit to the highest bit

           SCK = 1; // Pull SCK high, nRF24L01 reads 1 bit of data from MOSI and outputs 1 bit of data from MISO

           byte |= MISO; // Read MISO to the lowest bit of byte

           SCK = 0; // SCK is set low

       }

    return(byte); // Returns the read byte

}

/**************************************************/

/**************************************************

Function: SPI_RW_Reg()

describe:

    Write data value to register reg

/**************************************************/

uchar SPI_RW_Reg(uchar reg, uchar value)

{

    flying status;

      CSN = 0; // Set CSN to low and start transmitting data

      status = SPI_RW(reg); // Select register and return status word

      SPI_RW(value); // Then write data to this register

      CSN = 1; // Pull CSN high to end data transmission

      return(status); // Return status register

}

/**************************************************/

/**************************************************

Function: SPI_Read()

describe:

    Read a byte from register reg

/**************************************************/

fly SPI_Read(fly reg)

{

    fly reg_val;

      CSN = 0; // Set CSN to low and start transmitting data

      SPI_RW(reg); //Select register

      reg_val = SPI_RW(0); // Then read data from this register

      CSN = 1; // Pull CSN high to end data transmission

      return(reg_val); // Return register data

}

/**************************************************/

/**************************************************

Function: SPI_Read_Buf()

describe:

    Read bytes from the reg register, usually used to read the receiving channel

    Data or receiving/sending address

/**************************************************/

uchar SPI_Read_Buf(uchar reg, uchar * pBuf, uchar bytes)

{

    flying status, i;

      CSN = 0; // Set CSN to low and start transmitting data

      status = SPI_RW(reg); // Select register and return status word

      for(i=0; i        pBuf[i] = SPI_RW(0); // Read byte by byte from nRF24L01

      CSN = 1; // Pull CSN high to end data transmission

      return(status); // Return status register

}

/**************************************************/

/**************************************************

Function: SPI_Write_Buf()

describe:

    Write the data in the pBuf buffer to nRF24L01, usually used to write the send

    Receive/send channel data or address

/**************************************************/

uchar SPI_Write_Buf(uchar reg, uchar * pBuf, uchar bytes)

{

    flying status, i;

      CSN = 0; // Set CSN to low and start transmitting data

      status = SPI_RW(reg); // Select register and return status word

      for(i=0; i        SPI_RW(pBuf[i]); // Write byte by byte to nRF24L01

      CSN = 1; // Pull CSN high to end data transmission

      return(status); // Return status register

}

/**************************************************/

/**************************************************

Function: RX_Mode()

describe:

    This function sets the nRF24L01 to receive mode and waits for the data packet to be received from the sending device.

/**************************************************/

void RX_Mode(void)

{

    CE = 0;

      SPI_Write_Buf(WRITE_REG + RX_ADDR_P0, TX_ADDRESS, TX_ADR_WIDTH); // The receiving device receiving channel 0 uses the same transmit address as the transmitting device

      SPI_RW_Reg(WRITE_REG + EN_AA, 0x01); // Enable automatic response of receiving channel 0

      SPI_RW_Reg(WRITE_REG + EN_RXADDR, 0x01); // Enable receive channel 0

      SPI_RW_Reg(WRITE_REG + RF_CH, 40); // Select RF channel 0x40

      SPI_RW_Reg(WRITE_REG + RX_PW_P0, TX_PLOAD_WIDTH); // Receive channel 0 selects the same valid data width as the transmit channel

      SPI_RW_Reg(WRITE_REG + RF_SETUP, 0x07); // Data rate 1Mbps, transmit power 0dBm, low noise amplifier gain

      SPI_RW_Reg(WRITE_REG + CONFIG, 0x0f); // CRC enable, 16-bit CRC check, power on, receive mode

    delay_ms(150);

      CE = 1; // Pull up CE to start the receiving device

}

/**************************************************/

/**************************************************

Function: TX_Mode()

describe:

    This function sets nRF24L01 to transmit mode (CE=1 for at least 10us).

    After 130us, the transmission starts. After the data transmission is completed, the sending module automatically switches to receiving.

    Mode waits for response signal.

/**************************************************/

void TX_Mode(uchar * BUF)

{

    CE = 0;

      SPI_Write_Buf(WRITE_REG + TX_ADDR, TX_ADDRESS, TX_ADR_WIDTH); // Write transmit address

      SPI_Write_Buf(WRITE_REG + RX_ADDR_P0, TX_ADDRESS, TX_ADR_WIDTH); // To respond to the receiving device, the receiving channel 0 address is the same as the sending address

      SPI_Write_Buf(WR_TX_PLOAD, BUF, TX_PLOAD_WIDTH); // Write data packet to TX FIFO

      SPI_RW_Reg(WRITE_REG + EN_AA, 0x01); // Enable automatic response of receiving channel 0

      SPI_RW_Reg(WRITE_REG + EN_RXADDR, 0x01); // Enable receive channel 0

      SPI_RW_Reg(WRITE_REG + SETUP_RETR, 0x0a); // Automatic resend delay wait 250us+86us, automatic resend 10 times

      SPI_RW_Reg(WRITE_REG + RF_CH, 40); // Select RF channel 0x40

      SPI_RW_Reg(WRITE_REG + RF_SETUP, 0x07); // Data rate 1Mbps, transmit power 0dBm, low noise amplifier gain

      SPI_RW_Reg(WRITE_REG + CONFIG, 0x0e); // CRC enable, 16-bit CRC check, power on

    delay_ms(150);

    CE = 1;

}

/**************************************************/

/**************************************************

Function: Check_ACK()

describe:

    Check whether the receiving device has received the data packet, and set it to

    Is the number resent?

/**************************************************/

uchar Check_ACK(bit clear)