ft232rl_avr_example.c

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <string.h>
#include <ftdi.h>

#define PIN_BUFF  3
#define PIN_MOSI  6
#define PIN_MISO  4
#define PIN_SCK   2
#define PIN_RESET 5

#define CMD_RESULT_OK 0
#define CMD_RESULT_EXIT 1
#define CMD_RESULT_UNKNOWN 2

#define BAUDRATE 600
#define FT245R_CYCLES 2

#define SET_BITS_0(x,pinbit,level) (((x) & ~(pinbit)) | ((level) << (pinbit)))
#define GET_BITS_0(x,pinbit)       ((x) & (1 << (pinbit)))

typedef struct ftdi_context * pftdi;

unsigned char cur_state;

void debug(const char *fmt, ...)
{
  va_list arglist;
  va_start(arglist, fmt);
  vfprintf(stderr, fmt, arglist);
  va_end(arglist);
}

unsigned char *char2bin_str(unsigned char a, unsigned char *buffer) {
  int i;
  buffer[8] = 0;

  for (i = 7; i >= 0; i--) {
    buffer[i] = (a & 1) + '0';
    a >>= 1;
  }

  return buffer;
}

pftdi open_ft232rl()
{
  pftdi ftdi;
  int f;
  unsigned char mode = ~(1 << PIN_MISO);
  unsigned char mode_str[9];
  unsigned char tmp_buf[4096];

  if ((ftdi = ftdi_new()) == 0)
  {
    debug("ftdi_new failed\n");
    return NULL;
  }

  f = ftdi_usb_open(ftdi, 0x0403, 0x6001);

  if (f != 0)
  {
    debug("unable to open ftdi device: %d (%s)\n", f, ftdi_get_error_string(ftdi));
    return NULL;
  }

  ftdi_set_baudrate(ftdi, BAUDRATE);
  ftdi_set_bitmode(ftdi, mode, BITMODE_SYNCBB);

  ftdi_write_data(ftdi, &cur_state, 1);
  ftdi_read_data(ftdi, tmp_buf, sizeof(tmp_buf));

  return ftdi;
}

void close_ft232rl(pftdi ftdi)
{
  ftdi_disable_bitbang(ftdi);
  ftdi_usb_close(ftdi);
  ftdi_free(ftdi);
}

void set_pin(pftdi ftdi, unsigned char pin, unsigned char val)
{
  unsigned char tmp_buf;

  if (val)
    cur_state |= (1 << pin);
  else
    cur_state &= ~(1 << pin);

  ftdi_write_data(ftdi, &cur_state, 1);
  ftdi_read_data(ftdi, &tmp_buf, 1);
}

static inline int set_data(unsigned char *buf, unsigned char data) {
    int j;
    int buf_pos = 0;
    unsigned char bit = 0x80;

    for (j=0; j<8; j++) {
        cur_state = SET_BITS_0(cur_state, PIN_MOSI, data & bit);

        cur_state = SET_BITS_0(cur_state, PIN_SCK, 0);
        buf[buf_pos] = cur_state;
        buf_pos++;

        cur_state = SET_BITS_0(cur_state, PIN_SCK, 1);
        buf[buf_pos] = cur_state;
        buf_pos++;

        bit >>= 1;
    }
    return buf_pos;
}

static inline unsigned char extract_data(unsigned char *buf, int offset) {
    int j;
    int buf_pos = 1;
    unsigned char bit = 0x80;
    unsigned char r = 0;

    buf += offset * (8 * FT245R_CYCLES);
    for (j=0; j<8; j++) {
        if (GET_BITS_0(buf[buf_pos], PIN_MISO)) {
            r |= bit;
        }
        buf_pos += FT245R_CYCLES;
        bit >>= 1;
    }
    return r;
}

void avr_cmd(pftdi ftdi, unsigned char *cmd, unsigned char *out)
{
  int i;
  unsigned char tmp_buf;
  unsigned char buf[64];

  for (i = 0; i < 4; ++i) {
    set_data(buf + i, cmd[i]);
  }
  ftdi_write_data(ftdi, buf, 64);
  ftdi_read_data(ftdi, buf, 64);

  out[0] = extract_data(buf, 0);
  out[1] = extract_data(buf, 1);
  out[2] = extract_data(buf, 2);
  out[3] = extract_data(buf, 3);
}

void start_prog(pftdi ftdi)
{
  unsigned char in_buf[4];
  unsigned char ares[4];
  unsigned char buf_str[9];

  set_pin(ftdi, PIN_BUFF, 1);
  set_pin(ftdi, PIN_RESET, 0);
  set_pin(ftdi, PIN_SCK, 0);

  set_pin(ftdi, PIN_BUFF, 0);
  set_pin(ftdi, PIN_RESET, 1);
  usleep(50);

  set_pin(ftdi, PIN_RESET, 0);
  usleep(50);

  in_buf[0] = 0b10101100;
  in_buf[1] = 0b01010011;
  in_buf[2] = 0;
  in_buf[3] = 0;

  avr_cmd(ftdi, in_buf, ares);

  debug("result:");
  debug(" %s", char2bin_str(ares[0], buf_str));
  debug(" %s", char2bin_str(ares[1], buf_str));
  debug(" %s", char2bin_str(ares[2], buf_str));
  debug(" %s\n", char2bin_str(ares[3], buf_str));

  debug("Read from buffer %d bytes\n", ftdi_read_data(ftdi, buf_str, sizeof(buf_str)));
}

int main(int argc, char **argv)
{
  unsigned char acmd[4];
  unsigned char ares[4];
  pftdi ftdi;

  cur_state = 0xff;
  ftdi = open_ft232rl();

  if (!ftdi) {
    debug("can not open device\n");
    return 1;
  }

  start_prog(ftdi);

  close_ft232rl(ftdi);
}