/* plantower_SHT30_timer.ino, D. Brooks, January 2022
  PMS5003 with SHT30, timer on/off module to  minimize power.
  See plantower_SHT30_log for code to add more data,
  including AQI calculations, to the output.
*/
char filename[]="PM_TIMER.CSV";
#define KNT_MAX 50
#define WARMUP 60000L
#include <SoftwareSerial.h>
SoftwareSerial pmsSerial(2, 3);
#include <Adafruit_SHT31.h>
Adafruit_SHT31 sht31 = Adafruit_SHT31();
#include <Wire.h>
#include <SD.h>
#define SDpin 10
#include <SPI.h>
#include <RTClib.h>
RTC_DS1307 rtc; // "old" data logger shield
int knt=0,YR,MON,DY,HR,MIN,SEC;
const int donePIN=5;
float pm1=0,pm2_5=0,pm10=0,T,RH;
File logfile;
struct pms5003data {
uint16_t framelen;
uint16_t pm10_standard, pm25_standard, pm100_standard;
uint16_t pm10_env, pm25_env, pm100_env;
uint16_t particles_03um, particles_05um, particles_10um;
uint16_t particles_25um, particles_50um, particles_100um;
uint16_t unused;
uint16_t checksum;
};
struct pms5003data data;
void setup() {
  pinMode(donePIN,OUTPUT); digitalWrite(donePIN,LOW);
  delay(WARMUP); Serial.begin(9600); // just for testing...
  Wire.begin(); rtc.begin(); 
  pmsSerial.begin(9600);
  if (! sht31.begin(0x44)) {   // Set to 0x45 for alternate i2c addr
    Serial.println("Couldn't find SHT31"); while (1) delay(1);
  }
  Serial.print("Initializing SD card...");
  pinMode(SDpin,OUTPUT);
  if (!SD.begin(SDpin)) {Serial.println("Card failed."); 
  delay(50);exit(0);}
  Serial.println(F("card initialized."));  
  logfile=SD.open(filename,FILE_WRITE);  
  //---------------------------------------
  StartRead:
  if (readPMSdata(&pmsSerial)) { // reading data was successful!
    pm1+=data.pm10_env; pm2_5+=data.pm25_env; pm10+=data.pm100_env;
    //Serial.println(pm2_5);
    knt++;
    if (knt==KNT_MAX) {
      DateTime now=rtc.now();
      YR=now.year(); MON=now.month(); DY=now.day();
      HR=now.hour(); MIN=now.minute(); SEC=now.second();   
      pm1/=knt; pm2_5/=knt; pm10/=knt;  
      logfile.print(YR);  logfile.print(',');
      logfile.print(MON); logfile.print(',');
      logfile.print(DY);  logfile.print(',');
      logfile.print(HR);  logfile.print(',');
      logfile.print(MIN); logfile.print(',');
      logfile.print(SEC); logfile.print(',');
      logfile.print(DY+HR/24.+MIN/1440.+SEC/86400.,5);
      logfile.print(',');
      T=sht31.readTemperature(); RH=sht31.readHumidity();
      logfile.print(T,1);    logfile.print(',');
      logfile.print(RH,1);   logfile.print(',');        
      logfile.print(pm1,1);  logfile.print(','); 
      logfile.print(pm2_5,1); logfile.print(',');
      logfile.print(pm10,1); 
      logfile.println(); logfile.flush(); 
      Serial.println("finished..."); goto ShutDown;
    } 
  }
  goto StartRead;
  //---------------------------------------
  ShutDown:
  delay(50); digitalWrite(donePIN,HIGH);  
}
void loop() {}
boolean readPMSdata(Stream *s) {
if (! s->available()) {
return false;
}
// Read a byte at a time until we get to the special 
// '0x42' start-byte
if (s->peek() != 0x42) {s->read();return false;}
// Now read all 32 bytes
if (s->available() < 32) { return false;}
uint8_t buffer[32];
uint16_t sum = 0;
s->readBytes(buffer, 32);
// get checksum ready
for (uint8_t i=0; i<30; i++) {
sum += buffer[i];}
// The data comes in endian'd, this solves it so it works on all platforms
uint16_t buffer_u16[15];
for (uint8_t i=0; i<15; i++) {
  buffer_u16[i] = buffer[2 + i*2 + 1];
  buffer_u16[i] += (buffer[2 + i*2] << 8);}
// put it into a nice struct :)
memcpy((void *)&data, (void *)buffer_u16, 30);
if (sum != data.checksum) {
  Serial.println("Checksum failure");
  return false;}
// success!
return true;
}