BackgroundRead.ino File Reference

Example program for the INA Library demonstrating background reads. More...

#include <INA.h>

Functions
	ISR (PCINT0_vect)
void	setup ()
	Arduino method called once at startup to initialize the system. More...
void	loop ()

Variables
const uint8_t	INA_ALERT_PIN = 8
	Pin-Change pin used for the INA "ALERT" functionality.
const uint8_t	GREEN_LED_PIN = 13
	Arduino standard green LED.
const uint32_t	SERIAL_SPEED = 115200
	Use fast serial speed.
INA_Class	INA
	INA class instantiation.
volatile uint8_t	deviceNumber = UINT8_MAX
	Device Number to use in example.
volatile uint64_t	sumBusMillVolts = 0
	Sum of bus voltage readings.
volatile int64_t	sumBusMicroAmps = 0
	Sum of bus amperage readings.
volatile uint8_t	readings = 0
	Number of measurements taken.

Detailed Description

Example program for the INA Library demonstrating background reads.

Description

Program to demonstrate using the interrupt pin of any INA2xx which supports that functionality. It uses a pin-change interrupt handler and programs any INA2xx found to to read voltage and current information in the background while allowing the main Arduino code to continue processing normally until it is ready to consume the readings.

The example program uses the Arduino AVR-based interrupt mechanism and will not function on other platforms

Detailed documentation can be found on the GitHub Wiki pages at https://github.com/Zanduino/INA/wiki

Since the INA library allows multiple devices of different types and this program demonstrates interrupts and background processing, it will limit itself to using the first INA226 detected. This is easily changed in the if another device type or device number to test is required.
This example is for a INA226 set up to measure a 5-Volt load with a 0.1Ohm resistor in place, this is the same setup that can be found in the Adafruit INA226 breakout board. The complex calibration options are done at runtime using the 2 parameters specified in the "begin()" call and the library has gone to great lengths to avoid the use of floating point to conserve space and minimize runtime. This demo program uses floating point only to convert and display the data conveniently. The INA226 uses 15 bits of precision, and even though the current and watt information is returned using 32-bit integers the precision remains the same.
The INA226 is set up to measure using the maximum conversion length (and maximum accuracy) and then average those readings 64 times. This results in readings taking 8.244ms x 64 = 527.616ms or just less than 2 times a second. The pin-change interrupt handler is called when a reading is finished and the INA226 pulls the pin down to ground, it resets the pin status and adds the readings to the global variables. The main program will do whatever processing it has to and every 5 seconds it will display the current averaged readings and reset them.
The datasheet for the INA226 can be found at http://www.ti.com/lit/ds/symlink/INA226.pdf and it contains the information required in order to hook up the device. Unfortunately it comes as a VSSOP package but it can be soldered onto a breakout board for breadboard use. The INA226 is quite similar to the INA219 mentioned above, but it can take bus voltages of up to 36V (which I needed in order to monitor a 24V battery system which goes above 28V while charging and which is above the absolute limits of the INA219). It is also significantly more accurate than the INA219, plus has an alert pin.
The interrupt is set to pin 8. The tests were done on an Arduino Micro, and the Atmel 82U4 chip only allows pin change interrupt on selected pins (SS,SCK,MISO,MOSI,8) so pin 8 was chosen.

GNU General Public License v3.0

This program is free software : you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.You should have received a copy of the GNU General Public License along with this program(see https://github.com/Zanduino/INA/blob/master/LICENSE). If not, see http://www.gnu.org/licenses/.

Author

Written by Arnd Arnd@.nosp@m.Zand.nosp@m.uino..nosp@m.Com at https://www.github.com/SV-Zanshin

Changelog

Version	Date	Developer	Comments
1.0.5	2020-12-01	SV-Zanshin	Corrected "alertOnConversion()" call
1.0.4	2019-02-16	SV-Zanshin	ifdef so that sketch won't compile on incompatible platforms
1.0.3	2019-01-09	SV-Zanshin	Cleaned up doxygen formatting
1.0.2	2018-12-28	SV-Zanshin	Converted comments to doxygen format
1.0.0	2018-06-23	SV-Zanshin	Cloned and adapted example from old deprecated INA226

library

Function Documentation

ISR()

ISR

(

PCINT0_vect

)

Interrupt service routine for the PCINT0_vect

Routine is called whenever the INA_ALERT_PIN changes value

loop()

void loop

(

)

Arduino method for the main program loop

This is the main program for the Arduino IDE, it is called in an infinite loop. The INA226 measurements are triggered by the interrupt handler each time a conversion is ready and stored in variables. The main program doesn't call any INA library functions, that is done in the interrupt handler. Each time 10 readings have been collected the program will output the averaged values and measurements resume from that point onwards

Returns

void

setup()

void setup

(

)

Arduino method called once at startup to initialize the system.

This is an Arduino IDE method which is called first upon boot or restart. It is only called one time and then control goes to the main "loop()" method, from which control never returns

Returns

void