I am new to arduino and I am trying to make a program that calculates the percentage of charge remaining in a battery, using the coulomb countig method (below a picture with the formula). Is it possible to perform this type of calculation from an arduino?
1.) The Model
Assuming CBat is the capacity of a battery and constant (physicist prefer letter Q for electrical charge; CBat may decrease with aging, "State of Health")
By Definition:
SOC(t) = Q(t)/CBat
Differential Equation:
dQ/dt = I(t)
Approximation: "dt=1"
Q(t)-Q(t-1) ~= I(t)
Or
SOC(t) ~= SOC(t-1) + I(t)/Cbat
2.) Ardunio:
Following is a pure virtual script, online compiler would not serve.
// Assume current coming from serial port
const float C_per_Ah = 3600;
// signal adjustment
const float current_scale_A = 0.1; // Ampere per serial step
const int current_offset = 128; // Offset of serial value for I=0A
float CBat_Ah = 94; /* Assumed Battery Capacity in Ah */
float Cbat_C = CBat_Ah * C_per_Ah; /* ... in Coulomb */
float SOC = 0.7; /* Initial State of Charge */
int incomingByte = current_offset; // for incoming serial data, initial 0 Ampere
float I = 0; /* current */
// the setup routine runs once when you press reset:
void setup()
{
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
}
// the loop routine runs over and over again forever:
void loop()
{
delay(1000); // wait for a second
if (Serial.available() > 0)
{
// read the incoming byte:
incomingByte = Serial.read();
}
I = (incomingByte-current_offset) * current_scale_A;
SOC = SOC + I/Cbat_C;
Serial.print("New SOC: ");
Serial.println(SOC, 4);
}
I'm currently trying to set up a fermentation specific gravity monitor, using a tilt sensor. The process can take several weeks, and must be contained in a sterile container, so must be battery powerered. I'm using a slightly modified ESP8266-01, which enters sleep mode then wakes once an hour to take a measurement, transmit the data, and return to sleep mode. I'm using an MPU6050 for the tilt sensor. Firstly, I can't seem to put the mpu into sleep mode when the esp is off, it always seems to take around 4mA, and secondly, I only need one axis, is it possible to disable everything else to limit power consumption further? I can't seem to find anything in the manual to disable axis, only to calibrate them. my code is below
experimenting with the registers below seem to make no difference, adding them, taking them out altogether, still takes around 4mA. Tried setting to 1 to put the mpu to sleep at the end of the cycle but makes no difference.
Wire.write(0x6B);
Wire.write(0);
I'm very new to this and im struggling to interpret the manual when it refers to bit6 in addr 6b, how do i set bit 6?
If i could restict the mpu to only 1 axis, no acceleration, and to deep sleep inbetween measurements I should be able to get the power consumption around 0.5mA which gives me agood battery life using a single 18650. Any advice would be greatly appreciated!
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include "MPU6050.h"
#include "I2Cdev.h"
#include "Wire.h"
// Update these with values suitable for your network.
const char* ssid = "****";
const char* password = "******";
IPAddress server(192, 168, 1, 90);
WiFiClient espClient5;
PubSubClient client(espClient5);
long lastMsg = 0;
char msg[50];
const uint8_t scl = 5; //D1
const uint8_t sda = 4; //D2
int val;
int prevVal = 0;
String pubString;
char gravity[50];
MPU6050 mpu;
const int sleepTimeS = 10; //only 10 seconds for testing purposes, set to
1hr when operational
int counter=0;
int16_t ax, ay, az;
int16_t gx, gy, gz;
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) { //not
required in this application
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "test";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("AliveRegister", "FermentMon");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
#define ONE_WIRE_BUS 2 // D4 on physical board
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature DS18B20(&oneWire);
float prevTemp = 0;
void setup() {
counter = 0;
Serial.begin(9600);
Wire.begin(0,2);
Wire.write(0x6B); //PWR_MGMT_1 register
Wire.write(0); // set to zero wakes teh 6050
Wire.endTransmission(true);
delay(100);
setup_wifi();
client.setServer(server, 1883);
client.setCallback(callback);
if (!client.connected()) {
reconnect();
}
Serial.println("Initialize MPU");
mpu.initialize();
Serial.println(mpu.testConnection() ? "Connected" : "Connection failed");
float temp;
DS18B20.requestTemperatures();
temp = DS18B20.getTempCByIndex(0); // first temperature sensor
char buff[100];
dtostrf(temp, 0, 2, buff);
temp = temp + 0.5;
int tRound = int(temp);
client.publish("Fermenter/temperature", buff);
Serial.print("Fermenter Temperature: ");
Serial.println(temp);
prevTemp = tRound;
mpu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
val = map(ax, -17000, 17000, 0, 180);
pubString = String(val);
pubString.toCharArray(gravity, pubString.length() + 1);
client.publish("Fermenter/angle", gravity);
Serial.print("Gravity angle: ");
Serial.println(val);
delay(500);
// counter = counter+1;
Serial.println("sleep mode");
Wire.write(0x6B); //PWR_MGMT_1 register
Wire.write(1); // set to zero wakes teh 6050
// sleep
ESP.deepSleep(sleepTimeS * 1000000);
delay(2000);
}
void loop() {
client.loop();
}
I'm very new to this and im struggling to interpret the manual when it refers to bit6 in addr 6b, how do i set bit 6?
Setting a bit is simple.
Use the follow functions to avoid any brain storming.
// Write register bit
void writeRegisterBit(uint8_t reg, uint8_t pos, bool state)
{
uint8_t value;
value = readRegister8(reg);
if (state)
{
value |= (1 << pos);
}
else
{
value &= ~(1 << pos);
}
writeRegister8(reg, value);
}
// Write 8-bit to register
void writeRegister8(uint8_t reg, uint8_t value)
{
Wire.beginTransmission(MPU_addr);
#if ARDUINO >= 100
Wire.write(reg);
Wire.write(value);
#else
Wire.send(reg);
Wire.send(value);
#endif
Wire.endTransmission();
}
Example Usage: writeRegisterBit(MPU6050_REG_INT_PIN_CFG, 5, 1); //Register 37;Interrupt Latch Enable
For your application:
void acclSetSleepEnabled(bool state)
{
writeRegisterBit(MPU6050_REG_PWR_MGMT_1, 6, state);
}
If i could restict the mpu to only 1 axis, no acceleration, and to deep sleep inbetween measurements I should be able to get the power consumption around 0.5mA which gives me agood battery life using a single 18650
To enter low power accelerometer mode use the following function:
void lowPowerAccel(uint8_t frequency) {
uint8_t value;
value = readRegister8(MPU6050_REG_PWR_MGMT_2);
value &= 0b00111000;
value |= (frequency << 6) | 0b111;
writeRegister8(MPU6050_REG_PWR_MGMT_2, value);
value = readRegister8(MPU6050_REG_PWR_MGMT_1);
value &= 0b10010111;
value |= 0b00111000;
writeRegister8(MPU6050_REG_PWR_MGMT_1, value);
}
This lowPowerAccel function also puts the gyro to standy mode. The function needs a wake up frequency parameter.
This is defined as follows:
/*
* LP_WAKE_CTRL | Wake-up Frequency
* -------------+------------------
* 0 | 1.25 Hz
* 1 | 2.5 Hz
* 2 | 5 Hz
* 3 | 10 H
*/
#define LP_WAKE_CTRL_1_25 0x00
#define LP_WAKE_CTRL_2_5 0x01
#define LP_WAKE_CTRL_5 0x02
#define LP_WAKE_CTRL_10 0x03
I hope, I could answer some of your questions.
Good luck! :)
Are you using a breakout board for the MPU6050? e.g. GY-521. Often they use linear regulators and leds which will consume additional power. It may be necessary to remove these and run the IMU from a direct power source.
Each register in the MPU6050 is 8 bits wide. When setting an individual bit to a desired value you can either use bitwise manipulation (not practical here as we aren't directly interacting with the registers) or directly set all of the bits in the register to the register's new state e.g. 0b00100000 ~ 0x20. Instead of writing a 1 to 0x6B when attempting to put the MPU6050 to sleep you should be writing 0x20.
https://www.invensense.com/wp-content/uploads/2015/02/MPU-6000-Register-Map1.pdf
Referencing page 40-42, if you want to take things a step further you can disable the temperature sensor, accelerometers, and redundant gyroscope axes to save power while the device is active.
So I'm creating a code so that I can read and store temperature values
for at least 8hours and store it in the Arduino EEPROM. I also want the Built in LED to flash once every second, while the temperature sensor records once every minute. I wrote the following but I'm left with the LED staying on for a whole minute then off for another minute and so on. I want it to keep constantly flashing. I know it's because of my delay(6000) but I don't know how to fix it. Any help is appreciated, thanks!
#include <EEPROM.h> //LibrerÃa para controlar la EEPROM de la Arduino
float tempC; //Initialize variable for storing Temperature
int tempPin = 0; //Conected at A0
int addr = 0; //Cantidad de espacios (bytes) iniciales
int count = 0; //counter needed to stop at a certain point before overflowing the EEPROM memory
int Voltages[501]; // Array with space for 501 data Points.A little over 8 hours. Holding integer values of Voltages.
float Temps[501]; //Holds float values for Temperatures
const int SWITCH = 8; //set switch to port 8
int ledState = LOW; // ledState used to set the LED
unsigned long previousMillis = 0; // will store last time LED was updated
const long interval = 1000; // blink once per second
void setup(){
Serial.begin(115200);
pinMode(LED_BUILTIN,OUTPUT);
pinMode(SWITCH,INPUT_PULLUP);}
void loop(){
int i;
if (digitalRead(SWITCH)==HIGH & count<=501){
for (int i=0;i<EEPROM.length();i++){
EEPROM.write(i,0);} // Clears the EEPROM so that only new recorded values are shown. In case of terminating before 8h
Serial.println("-------Recording-------");
unsigned long currentMillis = millis(); // current time
if (currentMillis - previousMillis >= interval) {
previousMillis = currentMillis; // save the last time the LED blinked
if (ledState == LOW) {// if the LED is off turn it on and vice-versa:
ledState = HIGH;} else {
ledState = LOW;}
digitalWrite(LED_BUILTIN, ledState);}
for (i=0; i<501; i++){
count = count+1;
int v = analogRead(tempPin); // reads voltage
Voltages[i] = v;
Serial.println(i);
Serial.println(Voltages[i]);
delay(60000);
EEPROM.put(addr, Voltages[i]); //stores voltages in EEPROM
addr= addr +2;}}
I think the solution you are looking for involves the use of timer interrupts. That would execute an interrupt service routine (might as well be a blinking led) regardless of what happens in the rest of your loop function. This might give you a better in-sight: Arduino timer interrupts
I have a question about how to reading RPM and send value with serial
It's my code:
char init(void)
{
UBRRH=(uint8_t) (UBRR_CALC>>8);
UBRRL=(uint8_t) UBRR_CALC;
UCSRB=(1<<RXEN)|(1<<TXEN);
UCSRC=(1<<URSEL)|(3<<UCSZ0);
return 0;
}
void send(unsigned char x)
{
while(!(UCSRA&(1<<UDRE))){}
UDR=x;
}
void sendstring(char *s)
{
while(*s)
{
send(*s);
s++;
}
}
volatile uint16_t count=0; //Main revolution counter
volatile uint16_t rps=0; //Revolution per second
void Wait()
{
uint8_t i;
for(i=0;i<2;i++)
{
_delay_loop_2(0);
}
}
int main(void)
{
Wait();
Wait();
Wait();
Wait();
//Init INT0
MCUCR|=(1<<ISC01); //Falling edge on INT0 triggers interrupt.
GICR|=(1<<INT0); //Enable INT0 interrupt
//Timer1 is used as 1 sec time base
//Timer Clock = 1/1024 of sys clock
//Mode = CTC (Clear Timer On Compare)
TCCR1B|=((1<<WGM12)|(1<<CS12)|(1<<CS10));
//Compare value=976
OCR1A=976;
TIMSK|=(1<<OCIE1A); //Output compare 1A interrupt enable
//Enable interrupts globaly
sei();
while(1)
{
}
}
ISR(INT0_vect)
{
//CPU Jumps here automatically when INT0 pin detect a falling edge
count++;
}
ISR(TIMER1_COMPA_vect)
{
//CPU Jumps here every 1 sec exactly!
rps=count;
send(rps);
count=0;
}
Can we send serial data when interrupt counter and timer, i have error when try it ?
And what is the best methode to read RPM and send value with serial
One potential problem is that rps is defined as int16_t and your send routine is expecting an unsigned char.
Is the range 0-255 high enough for your RPS?
Do you want the RPS to be human readable or are you sending it to another computer or micro-controller?
It is possible to send serial in you interrupt routines but you need to be careful since the serial routines are not usually re-entrant.
i am new to Atmel, so maybe the question is quite simple.
I have the following situation:
I have an ATMega2560 and want to get Interrupts on the Pins PK0-PK7. I am interested in the PIN Change from Low to HIGH. (I have connected one photocell to every PIN)
I have read that the interrupt for PCINT[0-2] are fired everytime (pin high and pin low) so i defined an array to ignore the PIN DOWN Interrupt.
So i have the following code:
Note: I do not understand, why i need to set DDRC as input and not DDRK ?
#define HIGH 1
#define LOW 0
volatile uint8_t portbhistory = 0xFF;
uint8_t pinState[8];
void initSystem()
{
int i;
for(i = 0; i < sizeof(pinState) / sizeof(*pinState); i++)
{
pinState[8] = 0;
}
DDRB = 0xff; // set Port B as output
DDRC = 0; // WHY DDRC ?? PCINT == PK0-7, so DDRK ? // all Pins input
PORTC = 0xff; // same question ... // turn on pullup for every pin
PCICR |= _BV(PCIE2); // enable interrupt for PCIE2
PCMSK2 = 0xff; // Interrupt at all pins
sei(); // turn on interrupts
}
int main(void)
{
initSystem();
while(1)
{
}
}
ISR(PCINT2_vect)
{
int i;
uint8_t changedbits;
changedbits = PINC ^ portbhistory;
portbhistory = PINC;
/*
if(pinState[changedbits] == HIGH)
{
pinState[changedbits] = LOW;
return;
} else
{
pinState[changedbits] = HIGH;
}
*/
setDebugLED(1);
_delay_ms(30);
setDebugLED(0);
}
If i connect 5V to one of the PINS (PK0-7) the LED flashes instantly. But if i disconnect the 5V it takes ~2seconds for the LED to flash again. In this time the one pin i connected 5V before does not let the LED flash again if i connect the 5 V again.
Other Ports work in this time.
So you could say, that the PIN HIGH interrupt for all pins work fine and get fired instantly but the PIN LOW interrupts need some time (~2sec.) In this time the port is "disabled" or somethig.
Can anyone help me with that?
EDIT
Just some wrong edit ...
EDIT 2
So, i totally forgot to post my solution here. sorry for that!
The solution is: My external circuit pulls the PIN to Ground or to 5V.
Thank you!