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@maxupunk
Created May 22, 2017
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Arduino sketch for Open DC UPS Monitor: Arduino-based voltage monitor for unmanaged DC UPS devices powering unattended CLI Linux computers with DC-DC power supplies - SUSPENDED PROJECT.
/*
Open DC UPS Monitor (ODUMon) v.1.2
Any Arduino or Arduino compatible board should be able to run this sketch.
Open DC UPS Monitor is an Arduino-based voltage monitor for
unmanaged DC UPS devices powering unattended CLI Linux computers with DC-DC power supplies.
Dimitar D. Mitov, 2012 - 2014.
This file is in the public domain.
An interfacing script for the computer powered through ODUMon is also available and recommended.
Based on code from Olimex website:
https://www.olimex.com/Products/Duino/AVR/OLIMEXINO-32U4/resources/Shipping_Blink_Example.zip
Based on code from Arduino Playground:
http://arduino.cc/playground/Main/DirectMathVoltmeter
Created and tested with Olimexino-32U4 - an Arduino Leonardo implementation:
https://www.olimex.com/Products/Duino/AVR/OLIMEXINO-32U4/
Do not connect more than 5 Volts directly to your Arduino pins!
LED INDICATIONS:
================
COMPUTER POWER RELAY ON - GREEN LED IS CONTINUOUSLY ON
COMPUTER POWER RELAY OFF - GREEN LED IS OFF
*/
//// SETTINGS START HERE ////
// UPS PIN:
// +V from the UPS is connected through voltage divider to analog pin 0.
const int UPS_Voltage_Pin = A0;
// COMPUTER RELAY PIN:
// Digital pin 7 is used for the computer relay signal.
// Pin 7 is also connected to the built-in green LED of Olimexino-32U4.
// This could be usefull for testing without the external green LED.
// The external 12V encapsulated green LED of ODUMon is
// connected directly to the computer power relay.
const int Computer_Relay_Pin = 7;
// VOLTAGE REFERENCE:
const float Reference_Voltage = 5.0;
// RESISTOR VALUES:
// You can measure your resistors with a multimeter and put here their exact values.
// Note that the variables are of type "float" and they can accept an arbitrary decimal.
// Resistor values here are for a maximum input voltage of 15 V on a 5V Arduino board:
const float Resistor_1 = 2000; // 2K resistor
const float Resistor_2 = 1000; // 1K resistor
// VOLTAGES:
const float Maximal_Computer_Power_Supply_Voltage = 14.80;
const float Minimal_Online_Voltage = 13.60;
// Shutdown voltage should be more than
// the minimal voltage of the computer power supply
// for the computer to be properly powered during a normal shutdown.
const float Computer_Shutdown_Voltage = 11.25;
const float Minimal_Computer_Power_Supply_Voltage = 11.00;
// CUTOFF DELAY:
const int Computer_Power_Cutoff_Delay = 180000; // 3 minutes
//// SETTINGS END HERE ////
// INITIALISATIONS OF VARIABLES:
// Last state variable:
char Last_State;
// Voltage divider formula:
const float Denominator = Resistor_2 / (Resistor_1 + Resistor_2);
// Voltage variables:
float Voltage = 0.0;
float Maximal_Battery_Voltage_Under_Load = 0.0;
float First_Shutdown_Voltage_Measurement = 0.0;
float Second_Shutdown_Voltage_Measurement = 0.0;
// One percent of usable battery capacity (based on voltage measurement):
float One_Percent_of_Usable_Capacity = 0.0;
void setup(){
// Voltage Reference:
analogReference(DEFAULT);
// Computer relay pin as output:
pinMode(Computer_Relay_Pin, OUTPUT);
// UPS voltage pin as input:
pinMode(UPS_Voltage_Pin, INPUT);
// Begin serial communication:
Serial.begin(9600);
}
void loop(){
voltage_measurement:
// VOLTAGE MEASUREMENT:
// Read the raw data from the voltage divider:
float Analog_Read_Value = analogRead(UPS_Voltage_Pin);
// Calculate the input voltage:
float Input_Voltage = (Analog_Read_Value / 1024) * Reference_Voltage;
// Calculate the real voltage before the voltage divider:
Voltage = Input_Voltage / Denominator;
// OVERVOLTAGE:
if (Voltage > Maximal_Computer_Power_Supply_Voltage){
// Computer relay OFF:
digitalWrite(Computer_Relay_Pin,LOW);
//delay(150);
// Skip the rest, go to end and start again.
goto bailout;
}
// UNDERVOLTAGE:
if (Voltage < Minimal_Computer_Power_Supply_Voltage){
// Computer relay OFF:
digitalWrite(Computer_Relay_Pin,LOW);
//delay(150);
// Skip the rest, go to end and start again.
goto bailout;
}
// ON LINE VOLTAGE:
if (Voltage > Minimal_Online_Voltage && Voltage < Maximal_Computer_Power_Supply_Voltage){
// Computer relay ON:
digitalWrite(Computer_Relay_Pin,HIGH);
//delay(150);
// Serial console message formatted for the interfacing script on the ODUMon-powered computer.
Serial.print("ODUMon|OL|");
Serial.print(Voltage);
Serial.println("|END");
char Last_State = 'ONLINE';
// 1 sec. delay - i.e. read the UPS voltage every second:
delay(1000);
}
// ON BATTERY VOLTAGE - FIRST MEASUREMENT:
if (Voltage < Minimal_Online_Voltage &&
Voltage > Computer_Shutdown_Voltage && Last_State == 'ONLINE'){
Maximal_Battery_Voltage_Under_Load = Voltage;
// UPS Battery Usable Charge (based on voltage measurement):
float One_Percent_of_Usable_Capacity =
(Maximal_Battery_Voltage_Under_Load - Computer_Shutdown_Voltage) / 100;
// Computer relay ON:
digitalWrite(Computer_Relay_Pin,HIGH);
//delay(150);
// Serial console message formatted for the interfacing script on the ODUMon-powered computer.
Serial.print("ODUMon|OB|");
Serial.print(Voltage);
Serial.println("|100|END");
char Last_State = 'BATTERY';
// 1 sec. delay - i.e. read the UPS voltage every second:
delay(1000);
}
// ON BATTERY VOLTAGE -
// SECOND AND EVERY OTHER MEASUREMENT UNTIL
// COMPUTER SHUTDOWN VOLTAGE IS REACHED:
if (Voltage < Minimal_Online_Voltage &&
Voltage > Computer_Shutdown_Voltage && Last_State == 'BATTERY'){
// Computer relay ON:
digitalWrite(Computer_Relay_Pin,HIGH);
//delay(150);
float Remaining_Usable_Battery_Capacity =
(Voltage - Computer_Shutdown_Voltage) / One_Percent_of_Usable_Capacity;
// Serial console message formatted for the interfacing script on the ODUMon-powered computer.
Serial.print("ODUMon|OB|");
Serial.print(Voltage);
Serial.print("|");
Serial.print(Remaining_Usable_Battery_Capacity);
Serial.println("|END");
char Last_State = 'BATTERY';
// 1 sec. delay - i.e. read the UPS voltage every second:
delay(1000);
}
// COMPUTER SHUTDOWN VOLTAGE BEFORE SHUTDOWN COMMAND -
// FIRST MEASUREMENT:
if (Voltage <= Computer_Shutdown_Voltage &&
Last_State == 'BATTERY'){
float First_Shutdown_Voltage_Measurement = Voltage;
// Half a second delay before the next measurement:
delay(500);
goto voltage_measurement;
}
// COMPUTER SHUTDOWN VOLTAGE BEFORE SHUTDOWN COMMAND -
// SECOND MEASUREMENT:
if (Voltage <= Computer_Shutdown_Voltage &&
First_Shutdown_Voltage_Measurement <= Computer_Shutdown_Voltage &&
Last_State == 'BATTERY'){
float Second_Shutdown_Voltage_Measurement = Voltage;
// Half a second delay before the next measurement:
delay(500);
goto voltage_measurement;
}
// COMPUTER SHUTDOWN VOLTAGE -
// THIRD AND FINAL MEASUREMENT AND SHUTDOWN COMMAND:
if (Voltage <= Computer_Shutdown_Voltage &&
First_Shutdown_Voltage_Measurement <= Computer_Shutdown_Voltage &&
Second_Shutdown_Voltage_Measurement <= Computer_Shutdown_Voltage &&
Last_State == 'BATTERY'){
// Computer relay ON:
digitalWrite(Computer_Relay_Pin,HIGH);
//delay(150);
// Serial console message formatted for the interfacing script on the ODUMon-powered computer.
Serial.println("ODUMon|CR|END");
// Wait a predefined ammount of time before cutting off the DC power.
// This will allow the computer to shutdown gracefully.
delay(Computer_Power_Cutoff_Delay);
digitalWrite(Computer_Relay_Pin,LOW);
//delay(150);
char Last_State = 'SHUTDOWN';
float First_Shutdown_Voltage_Measurement = 0.0;
float Second_Shutdown_Voltage_Measurement = 0.0;
// 1 sec. delay - i.e. read the UPS voltage every second:
delay(1000);
goto voltage_measurement;
}
// COMPUTER SHUTDOWN VOLTAGE - AFTER SHUTDOWN:
if (Voltage <= Computer_Shutdown_Voltage && Last_State == 'SHUTDOWN'){
// Computer relay OFF:
digitalWrite(Computer_Relay_Pin,LOW);
//delay(150);
// 1 sec. delay - i.e. read the UPS voltage every second:
delay(1000);
goto voltage_measurement;
}
bailout:
// There must be something after a labeled point in the program.
delay(0);
}
// EOF
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