/*

compile: cc -o pcf8591 pcf8591.c

public domain by Shaddack

do what you wish

*/

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>


#define BASE_ADDR  0x48  // 0b 100 1xxx   xxx=A2,A1,A0

#define I2C_DEVICE "/dev/i2c-1"   // raspberry pi default


int verbose=0;

char i2cdevname[256];
int dev_addr=BASE_ADDR;

int pcfdac=-1;
int enabledac=0;
int pcfaddr=0;
int pcfmux=0;
int outjson=0;

int outhex=0;
int outchan=-1;

void pcf_setaddr(){
  if(pcfaddr<0)pcfaddr=0;
  if(pcfaddr>7)pcfaddr=7;
  dev_addr=BASE_ADDR+pcfaddr;
}



void pcf_i2cwrite(int file,int cfg,int dac){
  char buf[2];
  int cnt=1;
  if(dac>=0)cnt=2;
//  if(dac>255)dac=255;
  buf[0]=cfg;
  buf[1]=dac;
  if(verbose){fprintf(stderr,"raw write:");for(int t=0;t<cnt;t++)fprintf(stderr," %02x",buf[t]);fprintf(stderr,"\n");}
  if (write(file,buf,cnt) != cnt) {
    /* ERROR HANDLING: i2c transaction failed */
    perror("Failed to write to the i2c bus");
    fprintf(stderr,"Cannot talk to addr 0x%02x on bus '%s'.\n",dev_addr,i2cdevname);
    exit(1);
  }
}


void outnum(int n){
  if(outhex)printf("%02x",n);
  else printf("%d",n);
}


void readpcf8591(){
  int file;
  float lux;
  char buf[32]; // we need just 4 but overallocating is a good practice for one-off errors
  int bufr=8;

  // 7=0; 6=analog-out-active,act=H; 5,4=input mux (00=4-channels); 3=0; 2=autoincrement,act=H; 1,0=starting channel
  // b 0000 0100
  int conf=0x04;

  pcf_setaddr();

  if(enabledac)conf|=0x40;
  pcfmux&=0x03;
  if(pcfmux)conf|=(pcfmux << 4);

  if(verbose)fprintf(stderr,"accessing device 0x%02x on %s\n",dev_addr,i2cdevname);

  if ((file = open(i2cdevname, O_RDWR)) < 0) {
    /* ERROR HANDLING: you can check errno to see what went wrong */
    perror("Failed to open the i2c bus");
    fprintf(stderr,"bus '%s'\n",i2cdevname);
    exit(1);
  }

  if (ioctl(file, I2C_SLAVE, dev_addr) < 0) {
    /* ERROR HANDLING; you can check errno to see what went wrong */
    perror("IOCTL error on i2c bus");
    fprintf(stderr,"Failed to acquire bus access and/or talk to slave at 0x%02x.\n",dev_addr);
    exit(1);
  }

  if(verbose)fprintf(stderr,"Reading ADC with config byte = 0x%02x\n",conf);

  pcf_i2cwrite(file,conf,pcfdac);
 // bh_i2cwrite(file,0x00);
//  usleep(600000);

  buf[0]=0xff;buf[1]=0xfe; // make sure we're reading
  if (read(file,buf,bufr+1)!=bufr+1) {
    /* ERROR HANDLING: i2c transaction failed */
    perror("Failed to read from the i2c bus");
    fprintf(stderr,"Cannot talk to addr 0x%02x on bus '%s'.\n",dev_addr,i2cdevname);
    exit(1);
  }

  // ain0=photores (more light - value down), ain1=thermistor, ain2=in, ain3=trimpot
  // aout=LED
  // first two bytes invalid
  if(verbose){//printf("raw read: %02x %02x %02x %02x\n",buf[1],buf[2],buf[3],buf[4]);
    fprintf(stderr,"raw read:");
    //for(int t=0;t<bufr+1;t++)printf(" %02x",buf[t]);
    for(int t=2;t<6;t++)fprintf(stderr," %02x",buf[t]);
    fprintf(stderr,"\n");
    for(int t=0;t<bufr+1;t++)fprintf(stderr," %02x",buf[t]);fprintf(stderr,"\n");
  }

  if(outjson){
    printf("{\"ADC\":[%d,%d,%d,%d]}",buf[2],buf[3],buf[4],buf[5]);
    return;
  }

  if(outchan>3)outchan&=3;
  if(outchan<0){
    for(int t=0;t<4;t++){
      if(t)printf(" ");
      outnum(buf[t+2]);
    }
  }
  else outnum(buf[outchan+2]);
  printf("\n");

}


void help(){
  printf("PCF8591 sensor read\n");
  printf("Usage: pcf8591 [-v] [-x] [-O] [-o <DACval>] [-c <chan>] [-a <addr>] [-d <dev>]\n");
  printf("ADC:\n");
  printf("  -c <num>  display ADC channel (0..3), all if not specified\n");
  printf("  -m <num>  set the input mux (0..3) (bits 4,5 of config; default 0, four separate inputs)\n");
  printf("  -x        hex output\n");
  printf("  -j        json format\n");
  printf("DAC:\n");
  printf("  -O        force DAC output (do not unset when DAC value not specified)\n");
  printf("  -o <num>  set DAC value (0..255)\n");
  printf("I2C:\n");
  printf("  -a <num>  address, 0..7, default=0; adds to base address 0x%02x\n",BASE_ADDR);
  printf("  -d <dev>  specify I2C device, default %s\n",I2C_DEVICE);
  printf("general:\n");
  printf("  -v        verbose mode\n");
  printf("  -h,--help this help\n");
  printf("\n");
}


int main(int argc,char*argv[]){
  float lux;
  int t;

  strcpy(i2cdevname,I2C_DEVICE);

  for(t=1;t<argc;t++){
    // adc
    if(!strcmp(argv[t],"-c")){if(t+1<argc)outchan=strtoul(argv[t+1],NULL,0);t++;continue;}
    if(!strcmp(argv[t],"-m")){if(t+1<argc)pcfmux=strtoul(argv[t+1],NULL,0);t++;continue;}
    if(!strcmp(argv[t],"-x")){outhex=1;continue;}
    if(!strcmp(argv[t],"-j")){outjson=1;continue;}
    // dac
    if(!strcmp(argv[t],"-O")){enabledac=1;continue;}
    if(!strcmp(argv[t],"-o")){if(t+1<argc)pcfdac=strtoul(argv[t+1],NULL,0);t++;enabledac=1;continue;}
    // i2c
    if(!strcmp(argv[t],"-a")){if(t+1<argc)pcfaddr=strtoul(argv[t+1],NULL,0);t++;continue;}
    if(!strcmp(argv[t],"-d")){if(t+1<argc)strncpy(i2cdevname,argv[t+1],255);i2cdevname[255]=0;t++;continue;}
    // gen
    if(!strcmp(argv[t],"-v")){verbose=1;continue;}
    if(!strcmp(argv[t],"-h")){help();exit(0);}
    if(!strcmp(argv[t],"--help")){help();exit(0);}
    // err
    fprintf(stderr,"ERR: unknown parameter: %s\n",argv[t]);
    help();
    exit(1);
  }

  readpcf8591();
//  lux=readlux();
//  printf("%.1f\n",lux);
}