tm1640 and libftdi based clock and system status display

pins.h

#define PIN_TX  0x01  /* Orange wire on FTDI cable */
#define PIX_RX  0x02  /* Yellow */
#define PIN_RTS 0x04  /* Green */
#define PIN_CTS 0x08  /* Brown */
#define PIN_DTR 0x10
#define PIN_DSR 0x20
#define PIN_DCD 0x40
#define PIN_RI  0x80

tm1640.c

//  gcc tm1640.c -lftdi1 -o tm1640 -std=gnu99
#include <stdio.h>
#include <math.h>
#include <errno.h>
#include <error.h>
#include <libftdi1/ftdi.h>
#include <time.h>
#include <stdbool.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/sysinfo.h>
#include <signal.h>
#include <linux/kernel.h>

#include "pins.h"

#define DIN PIN_TX
#define SCLK PIN_DTR

const char FONT[]={
  0b00111111,
  0b00000110,
  0b01011011,
  0b01001111,
  0b01100110,
  0b01101101,
  0b01111101,
  0b00000111,
  0b01111111,
  0b01101111,
  0b11110111, // hex
  0b11111111,
  0b10111001,
  0b10111111,
  0b11111001,
  0b11110001
};

#define DOT 0b10000000

//#define ftdi_write_data(a,b,c) printf("SCLK: %d  DIN: %d\n", ((*b)&SCLK)>0,((*b)&DIN)>0);\
  ftdi_write_data(a,b,c);

void sendMarker(struct ftdi_context* ftdicv, struct timespec* sleeptimev,bool start){
//  printf("MARKER: %d\n", start);
  char pins=0;
  if(start){
    pins=SCLK|DIN;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins=SCLK;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins=0;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
  }else{
    pins=0;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins=SCLK;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins=SCLK|DIN;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
  }
}

void sendByte(struct ftdi_context* ftdicv, struct timespec* sleeptimev, unsigned char byte){
//  printf("BYTE: %x\n",byte);
  char pins=0;
  for(int i=0;i<8;i++){
    pins=((byte>>i)&1)<<(DIN-1);
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins|=SCLK;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
    pins^=SCLK;
    ftdi_write_data(ftdicv,&pins,1);
    nanosleep(sleeptimev,NULL);
  }
}

void sendAddressCmd(struct ftdi_context* ftdicv, struct timespec* sleeptimev, unsigned char addr){
//  printf("ADDRESS: %d\n", addr);
  sendByte(ftdicv,sleeptimev,0b11000000|(0b00001111&addr));
}

void sendDataCmd(struct ftdi_context* ftdicv, struct timespec* sleeptimev, bool autoincrement){
//  printf("DATA: %d\n", autoincrement);
  if(autoincrement)
    sendByte(ftdicv,sleeptimev,0b01000000);
  else
    sendByte(ftdicv,sleeptimev,0b01000100);
}

void sendBrightnessCmd(struct ftdi_context* ftdicv, struct timespec* sleeptimev, unsigned char bright){
//  printf("BRIGHTNESS: %d\n", bright);
  if(bright==0)
    sendByte(ftdicv,sleeptimev,0b10000000);
  else
    sendByte(ftdicv,sleeptimev,0b10001000|(0b00000111&bright-1));
}

bool turnOff;
bool notify;

void handle_signal(int signal) {
  switch (signal) {
    case SIGHUP:
    case SIGINT:
      turnOff=true;
      break;
    case SIGUSR1:
      notify=true;
  }
}
int main(int argc, char const *argv[])
{
  turnOff=false;
  notify=false;
  struct timespec sleeptime;
  sleeptime.tv_sec=0;
  sleeptime.tv_nsec = 500L;

  struct sigaction sa;
  sa.sa_handler=&handle_signal;
  sa.sa_flags = SA_RESTART;
  sigfillset(&sa.sa_mask);

  if (sigaction(SIGHUP, &sa, NULL) == -1) {
      perror("Can't handle SIGHUP");
  }
  if (sigaction(SIGINT, &sa, NULL) == -1) {
      perror("Can't handle SIGINT");
  }
  if (sigaction(SIGUSR1, &sa, NULL) == -1) {
      perror("Can't handle SIGUSR1");
  }

  struct ftdi_context ftdic;
  ftdi_init(&ftdic);

  if(ftdi_usb_open(&ftdic, 0x0403, 0x6001) < 0) {
    perror("Can't open device");
    return ENODEV;
  }

  if(ftdi_set_bitmode(&ftdic, DIN|SCLK,BITMODE_BITBANG)<0) {
    perror("Can't set bitbang mode");
    return EIO;
  }

  char pins=SCLK|DIN;
  ftdi_write_data(&ftdic,&pins,1);
  nanosleep(&sleeptime,NULL);

  sendMarker(&ftdic,&sleeptime,true);
  sendBrightnessCmd(&ftdic,&sleeptime,1);
  sendMarker(&ftdic,&sleeptime,false);

  sendMarker(&ftdic,&sleeptime,true);
  sendDataCmd(&ftdic,&sleeptime,true);
  sendMarker(&ftdic,&sleeptime,false);

  sendMarker(&ftdic,&sleeptime,true);
  sendAddressCmd(&ftdic,&sleeptime,0);
  for(int i=0;i<16;i++){
    sendByte(&ftdic,&sleeptime,0);
  }
  sendMarker(&ftdic,&sleeptime,false);

  time_t *timestamp=malloc(sizeof(time_t));
  struct tm *timestruct=malloc(sizeof(struct tm));
  unsigned char h1,h2,m1,m2,s1,s2;
  struct timespec looptime;
  looptime.tv_sec=0;
  looptime.tv_nsec = 50000000L;

  char obuf[16];
  char obufold[16];
  for(int i=0;i<16;i++){
    obuf[i]=0;
    obufold[i]=0;
  }

  FILE *psfp=fopen("/proc/stat","r");
  FILE *pmfp=fopen("/proc/meminfo","r");
  unsigned int cu,cn,cs,ci,cio,cirq,csirq,csum,cfree,coldfree,coldsum;
  double cuse,cavg;

  struct sysinfo *sysinfop=malloc(sizeof(struct sysinfo));
  double ruse;
  unsigned int rtotal,ravail;
  int frame=0;
  int notifycount=-1;
  double loadavg;
  while(!turnOff){
    time(timestamp);
    localtime_r(timestamp,timestruct);
    h1=timestruct->tm_hour/10;
    h2=timestruct->tm_hour%10;
    m1=timestruct->tm_min/10;
    m2=timestruct->tm_min%10;
    s1=timestruct->tm_sec/10;
    s2=timestruct->tm_sec%10;

    obuf[0]=FONT[h1];
    obuf[1]=FONT[h2]|DOT;
    obuf[2]=FONT[m1];
    obuf[3]=FONT[m2]|DOT;
    obuf[4]=FONT[s1];
    obuf[5]=FONT[s2]|((frame%2==0)?DOT:0);

    if(0!=sysinfo(sysinfop)) continue;

    loadavg=sysinfop->loads[0] / (double)(1<<SI_LOAD_SHIFT);
    if(loadavg>9.99){
      obuf[7]=FONT[(int)loadavg/10];
      obuf[8]=FONT[(int)loadavg%10]|DOT;
      obuf[9]=FONT[(int)(loadavg*10)%10];
    }else{
      obuf[7]=FONT[(int)loadavg%10]|DOT;
      obuf[8]=FONT[(int)(loadavg*10)%10];
      obuf[9]=FONT[(int)(loadavg*100)%10];
    }

    if(frame%15==0 ||frame==0){
      freopen("/proc/stat","r",psfp);
      fscanf(psfp,"cpu  %u %u %u %u %u %u %u",&cu,&cn,&cs,&ci,&cio,&cirq,&csirq);
      csum=cu+cn+cs+ci+cio+cirq+csirq;
      cfree=ci+cio;
      cuse=1.0-(double)(cfree-coldfree)/(double)(csum-coldsum);
      coldfree=cfree;
      coldsum=csum;
      if(cuse>0.99){
        obuf[11]=1;
        obuf[12]=1;
      }else{
        obuf[11]=FONT[(int)(cuse*10)%10];
        obuf[12]=FONT[(int)(cuse*100)%10];
      }

      freopen("/proc/meminfo","r",pmfp);
      fscanf(pmfp,"MemTotal: %u kB MemFree: %*u kB MemAvailable: %u kB", &rtotal, &ravail);
      ruse=1.0-((double)ravail/(double)rtotal);
      //1.0-(double)(sysinfop->freeram + sysinfop->bufferram + sysinfop->freehigh)/(double)(sysinfop->totalhigh + sysinfop->totalram);

      if(ruse>0.99){
        obuf[14]=1;
        obuf[15]=1;
      }else{
        obuf[14]=FONT[(int)(ruse*10)%10];
        obuf[15]=FONT[(int)(ruse*100)%10];
      }
    }


    if(notify){
      notifycount=4;
      notify=false;
    }

    if(notifycount>0){
      for(int i=0;i<16;i++){
        if(notifycount%2==0)
          obuf[i]=FONT[8];
        else
          obuf[i]=0;
      }
    }
    if(notifycount>=0){
      for(int i=0;i<notifycount;i++)
        obuf[i]|=DOT;
      notifycount--;
    }

    for(int i=0;i<16;i++){
      if(obuf[i]==obufold[i])
        continue;
      sendMarker(&ftdic,&sleeptime,true);
      sendAddressCmd(&ftdic,&sleeptime,i);
      while(obuf[i]!=obufold[i] && i<16){
//        printf("buf %d\n",i);
        sendByte(&ftdic,&sleeptime,obuf[i]);
        obufold[i]=obuf[i];
        i++;
      }
      sendMarker(&ftdic,&sleeptime,false);
    }
    frame++;
    nanosleep(&looptime,NULL);
  }

  sendMarker(&ftdic,&sleeptime,true);
  sendAddressCmd(&ftdic,&sleeptime,0);
  for(int i=0;i<16;i++){
    sendByte(&ftdic,&sleeptime,0);
  }
  sendMarker(&ftdic,&sleeptime,false);

  pins=0;
  ftdi_write_data(&ftdic,&pins,1);
  fclose(psfp);

  return 0;
}