Background Info
Uno R3 (w/ DIP-mounted controller)
Arduino IDE 2.3.4
PZEM-004T (v3) sensor module for AC power monitoring
Adafruit RTC + SD-Card shield (RTC is based on the the PCF8523 chip)
Problem
I began with the LCD-display code supplied from Miliohm (sic) guide to the PZEM-004T, which relies on PZEM004Tv30.h in the PZEM004Tv30 library of Jakub Mandula.
I then modified the hardware, adding an Adafruit RTC clock + SD-Card shield. Working methodically, step-wise, I proved that adding the shield did not cause interference with the original code.
I then modified that code from the Miliohm tutorial: I added RTC functionality, and added the Serial.print (but not lcd.print, because the display is always "real time") so that it spits out the real time as Unixtime each time the PZEM module is queried. The serial output looks like this:
Unixtime: 1740396098
Voltage: 121.20V
Current: 0.00A
Power: 0.00W
Energy: 0.000kWh
Frequency: 60.0Hz
Φ: 0.00
I then modified that code, so that I can write the data to an SD card.
I used dataString so that I can write the data in CSV format to the SD card.
I was able to create a dataString that includes all of the named values generated within PZEM004Tv30.h. As things stand now, the Sketch happily writes those values to the SD card, and I can then read them within Excel (etc etc)
However...
For the life of me, I cannot figure out how to add the value of Unixtime to the dataString. Intuitively, this would seem to be a trival matter, but clearly I am not playing with a full deck of cards...
Here is the full code
#include <PZEM004Tv30.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "RTClib.h"
#include <SD.h>
const int chipSelect = 10;
float mark;
RTC_PCF8523 rtc;
char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
LiquidCrystal_I2C lcd(0x27, 16, 2);
PZEM004Tv30 pzem(8, 9); // Software Serial pin 8 (RX) & 9 (TX)
String dataString =""; // holds the data to be written to the SD card
File pzemData;
//
//
void setup(){
// Open serial communications
Serial.begin(9600);
Serial.print("Initializing SD card...");
pinMode(chipSelect, OUTPUT);
//
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
Serial.println("Card failed, or not present");
// don't do anything more:
return;
}
Serial.println("card initialized.");
// define RTclock functions and set clock, lines 22-78 inclusive
if (! rtc.begin()) {
Serial.println("Couldn't find RTC");
Serial.flush();
while (1) delay(10);
}
if (! rtc.initialized() || rtc.lostPower()) {
Serial.println("RTC is NOT initialized, let's set the time!");
// When time needs to be set on a new device, or after a power loss, the
// following line sets the RTC to the date & time this sketch was compiled
rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
// This line sets the RTC with an explicit date & time, for example to set
// January 21, 2014 at 3am you would call:
// rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
//
// Note: allow 2 seconds after inserting battery or applying external power
// without battery before calling adjust(). This gives the PCF8523's
// crystal oscillator time to stabilize. If you call adjust() very quickly
// after the RTC is powered, lostPower() may still return true.
}
// When time needs to be re-set on a previously configured device, the
// following line sets the RTC to the date & time this sketch was compiled
// rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
// This line sets the RTC with an explicit date & time, for example to set
// January 21, 2014 at 3am you would call:
// rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
// When the RTC was stopped and stays connected to the battery, it has
// to be restarted by clearing the STOP bit. Let's do this to ensure
// the RTC is running.
rtc.start();
// The PCF8523 can be calibrated for:
// - Aging adjustment
// - Temperature compensation
// - Accuracy tuning
// The offset mode to use, once every two hours or once every minute.
// The offset Offset value from -64 to +63. See the Application Note for calculation of offset values.
// https://www.nxp.com/docs/en/application-note/AN11247.pdf
// The deviation in parts per million can be calculated over a period of observation. Both the drift (which can be negative)
// and the observation period must be in seconds. For accuracy the variation should be observed over about 1 week.
// Note: any previous calibration should cancelled prior to any new observation period.
// Example - RTC gaining 43 seconds in 1 week
float drift = 43; // seconds plus or minus over oservation period - set to 0 to cancel previous calibration.
float period_sec = (7 * 86400); // total obsevation period in seconds (86400 = seconds in 1 day: 7 days = (7 * 86400) seconds )
float deviation_ppm = (drift / period_sec * 1000000); // deviation in parts per million (μs)
float drift_unit = 4.34; // use with offset mode PCF8523_TwoHours
// float drift_unit = 4.069; //For corrections every min the drift_unit is 4.069 ppm (use with offset mode PCF8523_OneMinute)
int offset = round(deviation_ppm / drift_unit);
// rtc.calibrate(PCF8523_TwoHours, offset); // Un-comment to perform calibration once drift (seconds) and observation period (seconds) are correct
// rtc.calibrate(PCF8523_TwoHours, 0); // Un-comment to cancel previous calibration
Serial.print("Offset is "); Serial.println(offset); // Print to control offset
//end setting of RTclock functions
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0);
lcd.print("PZEM Test");
lcd.setCursor(0, 1);
lcd.print("by Miliohm.com");
delay(2000);
lcd.clear();
}
void loop() {
DateTime now = rtc.now();
Serial.print("Unixtime: ");
Serial.print(now.unixtime());
Serial.println();
float voltage = pzem.voltage();
if (voltage != NAN) {
Serial.print("Voltage: ");
Serial.print(voltage);
Serial.println("V");
lcd.setCursor(0, 0);
lcd.print("V");
lcd.print(voltage);
} else {
Serial.println("Error reading voltage");
}
float current = pzem.current();
if (current != NAN) {
Serial.print("Current: ");
Serial.print(current);
Serial.println("A");
lcd.setCursor(0, 1);
lcd.print("A");
lcd.print(current);
} else {
Serial.println("Error reading current");
}
float power = pzem.power();
if (current != NAN) {
Serial.print("Power: ");
Serial.print(power);
Serial.println("W");
lcd.setCursor(6, 0);
lcd.print("W");
lcd.print(power);
} else {
Serial.println("Error reading power");
}
float energy = pzem.energy();
if (current != NAN) {
Serial.print("Energy: ");
Serial.print(energy, 3);
Serial.println("kWh");
lcd.setCursor(4, 1);
lcd.print("kWh");
lcd.print(energy);
} else {
Serial.println("Error reading energy");
}
float frequency = pzem.frequency();
if (current != NAN) {
Serial.print("Frequency: ");
Serial.print(frequency, 1);
Serial.println("Hz");
lcd.setCursor(11, 0);
lcd.print("f");
lcd.print(frequency);
} else {
Serial.println("Error reading frequency");
}
float pf = pzem.pf();
if (current != NAN) {
Serial.print("Φ: ");
Serial.println(pf);
lcd.setCursor(11,1);
lcd.print("pF");
lcd.print(pf);
} else {
Serial.println("Error reading power factor");
}
Serial.println();
// SD Card writing based on https://rydepier.wordpress.com/2015/08/07/using-an-sd-card-reader-to-store-and-retrieve-data-with-arduino/1740349303Conv
// build the data string
dataString = String(voltage) + "," + String(current) + "," + String(power) + "," + String(frequency) + "," + String(pf); // convert to CSV
//saveData(); // save to SD card
delay(2000); // delay before next write to SD Card, adjust as required
}
//
void saveData(){
if(SD.exists("data.csv")){ // check the card is still there!
// now, let's append new data file!
pzemData = SD.open("data.csv", FILE_WRITE);
if (pzemData){
pzemData.println(dataString);
pzemData.close(); // close the file
}
else{
Serial.println("Error writing to file !");
}
}
delay(2000);
}
Any & all helpful suggestions would appreciated.