NRF24L01 and FTDI

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <ftdi.h>

#define PIN_TXD  0x01
#define PIN_RXD  0x02
#define PIN_RTS 0x04
#define PIN_CTS 0x08
#define PIN_DTR 0x10
#define PIN_DSR 0x20
#define PIN_DCD 0x40
#define PIN_RI  0x80

#define PIN_IRQ PIN_DSR
#define PIN_SCK PIN_DCD
#define PIN_MISO PIN_RXD
#define PIN_MOSI PIN_TXD
#define PIN_CSN PIN_DTR
#define PIN_CE PIN_RI
#define PIN_LED PIN_CTS

#define FTDI_BAUDRATE 3000000

struct ftdi_context ftdic;
int pin_state;
uint8_t nrf24l01_status;

void spi_request(uint8_t *tx_data, uint8_t *rx_data, int count) {
    int i, j;
    uint8_t tx_buffer[count * 8 * 2 + 4];
    uint8_t rx_buffer[count * 8 * 2 + 4];
    int k = 0;
    tx_buffer[k++] = pin_state | PIN_CSN;
    tx_buffer[k++] = pin_state;
    for (i = 0; i < count; i++) {
        int byte = *tx_data;
        for (j = 0; j < 8; j++) {
            int bit = (byte >> 7) & 1;
            if (bit) {
                tx_buffer[k++] = pin_state | PIN_MOSI;
                tx_buffer[k++] = pin_state | PIN_SCK | PIN_MOSI;
            } else {
                tx_buffer[k++] = pin_state;
                tx_buffer[k++] = pin_state | PIN_SCK;

            }
            byte <<= 1;
        }
        tx_data++;
    }
    tx_buffer[k++] = pin_state;
    tx_buffer[k++] = pin_state | PIN_CSN;
    ftdi_write_data(&ftdic, tx_buffer, sizeof(tx_buffer));
    ftdi_read_data(&ftdic, rx_buffer, sizeof(rx_buffer));
    if (rx_data) {
        k = 3;
        for (i = 0; i < count; i++) {
            int byte = 0;
            for (j = 0; j < 8; j++) {
                k++;
                byte <<= 1;
                if (rx_buffer[k++] & PIN_MISO) {
                    byte |= 1;
                }
            }
            *rx_data = byte;
            rx_data++;
        }
    }
}

void nrf24l01_ce_pulse() {
    uint8_t buffer = pin_state | PIN_CE;
    ftdi_write_data(&ftdic, &buffer, sizeof(buffer));
    usleep(10);
    buffer &= ~PIN_CE;
    ftdi_read_data(&ftdic, &buffer, sizeof(buffer));
}

uint8_t nrf24l01_nop() {
    uint8_t buffer[] = {0xFF};
    spi_request(buffer, buffer, sizeof(buffer));
    nrf24l01_status = buffer[0];
    return nrf24l01_status;
}

void nrf24l01_write_byte_reg(uint8_t reg, uint8_t value) {
    uint8_t buffer[] = {0x20 | reg, value};
    spi_request(buffer, buffer, sizeof(buffer));
    nrf24l01_status = buffer[0];
}

void nrf24l01_write_long_reg(uint8_t reg, unsigned long long value) {
    uint8_t buffer[1 + 5];
    buffer[0] = 0x20 | reg;
    memmove(buffer + 1, &value, 5);
}

uint8_t nrf24l01_read_byte_reg(uint8_t reg) {
    uint8_t buffer[] = {reg, 0};
    spi_request(buffer, buffer, sizeof(buffer));
    nrf24l01_status = buffer[0];
    return buffer[1];
}

unsigned long long nrf24l01_read_long_reg(uint8_t reg) {
    uint8_t buffer[1 + 5];
    buffer[0] = reg;
    spi_request(buffer, buffer, sizeof(buffer));
    nrf24l01_status = buffer[0];
    return *((unsigned long long*)(buffer + 1));
}

void nrf24l01_tx_payload(uint8_t *data, int len) {
    uint8_t buffer[len + 1];
    buffer[0] = 0xA0;
    memmove(buffer + 1, data, len);
    spi_request(buffer, buffer, sizeof(buffer));
    nrf24l01_status = buffer[0];
}

void nrf24l01_rx_payload(uint8_t *data, int len) {
    uint8_t buffer[len + 1];
    buffer[0] = 0x61;
    spi_request(buffer, buffer, sizeof(buffer));
    memmove(data, buffer + 1, len);
    nrf24l01_status = buffer[0];
}

void nrf24l01_send_packet(uint8_t *data, int len) {
    nrf24l01_tx_payload(data, len);
    nrf24l01_ce_pulse();
}

void nrf24l01_dump_regs() {
    printf("NRF24L01+ register values:\n");
    printf("\tCONFIG = %x\n", nrf24l01_read_byte_reg(0));
    printf("\tEN_AA = %x\n", nrf24l01_read_byte_reg(1));
    printf("\tEN_RXADDR = %x\n", nrf24l01_read_byte_reg(2));
    printf("\tSETUP_AW = %x\n", nrf24l01_read_byte_reg(3));
    printf("\tSETUP_RETR = %x\n", nrf24l01_read_byte_reg(4));
    printf("\tRF_CH = %x\n", nrf24l01_read_byte_reg(5));
    printf("\tRF_SETUP = %x\n", nrf24l01_read_byte_reg(6));
    printf("\tSTATUS = %x\n", nrf24l01_read_byte_reg(7));
    printf("\tOBSERVE_TX = %x\n", nrf24l01_read_byte_reg(8));
    printf("\tCD = %x\n", nrf24l01_read_byte_reg(9));
    printf("\tRX_ADDR_P0 = %x\n", nrf24l01_read_long_reg(10));
    printf("\tRX_ADDR_P1 = %x\n", nrf24l01_read_long_reg(11));
    printf("\tRX_ADDR_P2 = %x\n", nrf24l01_read_byte_reg(12));
    printf("\tRX_ADDR_P3 = %x\n", nrf24l01_read_byte_reg(13));
    printf("\tRX_ADDR_P4 = %x\n", nrf24l01_read_byte_reg(14));
    printf("\tRX_ADDR_P5 = %x\n", nrf24l01_read_byte_reg(15));
    printf("\tTX_ADDR = %x\n", nrf24l01_read_long_reg(16));
    printf("\tRX_PW_P0 = %x\n", nrf24l01_read_byte_reg(17));
    printf("\tRX_PW_P1 = %x\n", nrf24l01_read_byte_reg(18));
    printf("\tRX_PW_P2 = %x\n", nrf24l01_read_byte_reg(19));
    printf("\tRX_PW_P3 = %x\n", nrf24l01_read_byte_reg(20));
    printf("\tRX_PW_P4 = %x\n", nrf24l01_read_byte_reg(21));
    printf("\tRX_PW_P5 = %x\n", nrf24l01_read_byte_reg(22));
    printf("\tFIFO_STATUS = %x\n", nrf24l01_read_byte_reg(23));
    printf("\tDYNPD = %x\n", nrf24l01_read_byte_reg(0x1C));
    printf("\tFEATURE = %x\n", nrf24l01_read_byte_reg(0x1D));
}

int main(int argc, char **argv) {
    ftdi_init(&ftdic);
    if (ftdi_usb_open(&ftdic, 0x0403, 0x6001) < 0) {
        fprintf(stderr, "Error: failed to open FTDI device!\n");
        return 1;
    }
    if (ftdi_set_baudrate(&ftdic, FTDI_BAUDRATE) < 0) {
        ftdi_usb_close(&ftdic);
        fprintf(stderr, "Warning: failed to set bitbang baudrate!\n");
    }
    ftdi_set_bitmode(&ftdic, PIN_LED | PIN_SCK | PIN_MOSI | PIN_CSN | PIN_CE, BITMODE_SYNCBB);
    {
        uint8_t pin_state = PIN_CSN;
        ftdi_write_data(&ftdic, &pin_state, sizeof(pin_state));
        ftdi_read_data(&ftdic, &pin_state, sizeof(pin_state));
    }
    pin_state |= PIN_LED;
    nrf24l01_dump_regs();
    nrf24l01_send_packet("HELLO", 6);
    pin_state &= ~PIN_LED;
    nrf24l01_nop();
    sleep(2);
    printf("%x\n", nrf24l01_read_byte_reg(7));
    ftdi_usb_close(&ftdic);
    return 0;
}