AQM1248 hadling example for Raspberry Pi via file system version.fill gray all area.

aqm1248fs.c

// AQM1248 hadling example for Raspberry Pi
// via file system version
// compile: cc aqm1248fs.c -o aqm1248fs
// execute: sudo ./aqm1248fs

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

#define CONTRUST 0x1c
#define PORT_RS 25

int passign(int port){
  int ret;
  int fd;
  char buf[40];

  // enable port
  fd = open("/sys/class/gpio/export", O_WRONLY);
  if(fd == -1){
    fprintf(stderr, "fail to open GPIO%d. %s\n", port, strerror(errno));
    return -1;
  }
  sprintf(buf, "%d", port);
  ret = write(fd, buf, strlen(buf));
  close(fd);
  if(ret <= 0){
    fprintf(stderr, "fail to open GPIO%d. %s\n", port, strerror(errno));
    return -1;
  }

  // set port as output
  sprintf(buf, "/sys/class/gpio/gpio%d/direction", port);
  fd = open(buf, O_WRONLY);
  write(fd, "out", 3);
  close(fd);

  // open port for write
  sprintf(buf, "/sys/class/gpio/gpio%d/value", port);
  fd = open(buf, O_WRONLY);

  return fd;
}

void pfree(int port){
  int fd;
  char buf[40];

  // disable port
  fd = open("/sys/class/gpio/unexport", O_WRONLY);
  sprintf(buf, "%d", port);
  write(fd, buf, strlen(buf));
  close(fd);
}

int transfer(int fd, uint8_t value){
  int ret;
  uint8_t tx;

  struct spi_ioc_transfer tr ={
    .tx_buf = (uint32_t)&tx,
    .rx_buf = (uint32_t)NULL,
    .len = 1,
    .delay_usecs = 0,
    .speed_hz = 2000000,
    .bits_per_word = 8,
  };

  tx = value;
  ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
  if(ret < 1){
    fprintf(stderr, "can't send spi message\n");
    return -1;
  }
  return 0;
}

#define CONTRUST 0x1c

int main(int argc, char *argv[]){
  int i, j;
  int ret = 0;
  int pfd;
  int sfd;

  pfree(PORT_RS);
  pfd = passign(PORT_RS);
  sfd = open("/dev/spidev0.0", O_RDWR);
  if(pfd < 0 || sfd < 0){
    fprintf(stderr, "can't open device\n");
    return -1;
  }

  write(pfd, "0", 2);
  transfer(sfd, 0xae);
  transfer(sfd, 0xa0);
  transfer(sfd, 0xc8);
  transfer(sfd, 0xa3);
  transfer(sfd, 0x2c); usleep(2000);
  transfer(sfd, 0x2e); usleep(2000);
  transfer(sfd, 0x2f);
  transfer(sfd, 0x23);
  transfer(sfd, 0x81);
  transfer(sfd, CONTRUST);
  transfer(sfd, 0xa4);
  transfer(sfd, 0x40);
  transfer(sfd, 0xa6);
  transfer(sfd, 0xaf);

  for(i = 0; i < 6; i++){
    transfer(sfd, 0xb0 | i);//page
    transfer(sfd, 0x10);//column 0
    transfer(sfd, 0x00);

    write(pfd, "1", 2);
    for(j = 0; j < 64; j++){
      transfer(sfd, 0x55);
      transfer(sfd, 0xaa);
    }
    write(pfd, "0", 2);
  }

  close(pfd);
  pfree(PORT_RS);
  close(sfd);
  return 0;
}