174 lines
5.2 KiB
C++
174 lines
5.2 KiB
C++
// USB Power Tester - Basic
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//
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// This code implements the basic functionality for the USB Power Tester.
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// It reads voltage, current and power from the INA219, calculates capacity
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// and shows the values on the OLED. It uses a reduced character set in order
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// to make it fit on an ATtiny45. The SET button is used to switch between
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// the "recent value screen" and the "min/max value screen".
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//
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// +-\/-+
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// RESET --- A0 (D5) PB5 1| |8 Vcc
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// SET ----- A3 (D3) PB3 2| |7 PB2 (D2) A1 ---- OLED/INA (SCK)
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// A2 (D4) PB4 3| |6 PB1 (D1)
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// GND 4| |5 PB0 (D0) ------- OLED/INA (SDA)
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// +----+
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//
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// Controller: ATtiny45/85
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// Core: ATTinyCore (https://github.com/SpenceKonde/ATTinyCore)
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// Clockspeed: 8 MHz internal
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// Millis: enabled
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//
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// 2020 by Stefan Wagner (https://easyeda.com/wagiminator)
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// License: http://creativecommons.org/licenses/by-sa/3.0/
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//Libraries
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#include <TinyI2CMaster.h> // https://github.com/technoblogy/tiny-i2c
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#include <Tiny4kOLED.h> // https://github.com/datacute/Tiny4kOLED
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#include <avr/pgmspace.h> // for using data in program space
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#include "font8x16a.h" // reduced character set
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// Pin definitions
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#define SETBUTTON 3
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// INA219 register values
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#define INA_ADDR 0b01000000 // I2C address of INA219
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#define INA_CONFIG 0b0000011001100111 // INA config register according to datasheet
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#define INA_CALIB 5120 // INA calibration register according to R_SHUNT
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#define CONFIG_REG 0x00 // INA configuration register address
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#define CALIB_REG 0x05 // INA calibration register address
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#define SHUNT_REG 0x01 // INA shunt voltage register address
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#define VOLTAGE_REG 0x02 // INA bus voltage register address
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#define POWER_REG 0x03 // INA power register address
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#define CURRENT_REG 0x04 // INA current register address
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// Conversions for the reduced character set
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#define mV ".,*"
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#define mA ".+*"
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#define mW ".-*"
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#define mAh ".+/"
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#define SEP "*)*"
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#define SPACE "*"
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// Variables (voltage in mV, current in mA, power in mW)
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uint16_t voltage, current, power;
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uint16_t minvoltage = 65535, maxvoltage = 0;
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uint16_t mincurrent = 65535, maxcurrent = 0;
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uint32_t lastmillis, nowmillis, interval;
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uint32_t capacity = 0;
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bool primescreen = true;
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bool lastbutton = true;
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void setup() {
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// setup pins
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DDRB = 0; // all pins input now
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PORTB = bit (SETBUTTON); // pullup for set button
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// start I2C
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TinyI2C.init();
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// start INA219
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initINA();
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// start OLED
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oled.begin();
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oled.setFont(FONT8X16A);
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oled.clear();
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oled.on();
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oled.switchRenderFrame();
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// init some variables
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lastmillis = millis();
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}
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void loop() {
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// read voltage, current and power from INA219
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updateINA();
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// update min/max values
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if (minvoltage > voltage) minvoltage = voltage;
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if (maxvoltage < voltage) maxvoltage = voltage;
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if (mincurrent > current) mincurrent = current;
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if (maxcurrent < current) maxcurrent = current;
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// calculate power in mW
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power = (uint32_t)voltage * current / 1000;
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// calculate capacity in uAh
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nowmillis = millis();
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interval = nowmillis - lastmillis; // calculate time interval
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lastmillis = nowmillis;
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capacity += interval * current / 3600; // calculate uAh
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// check button
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if (bitRead(PINB, SETBUTTON)) lastbutton = false;
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else if (!lastbutton) {
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primescreen = !primescreen;
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lastbutton = true;
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}
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// display values on the oled
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oled.clear();
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oled.setCursor(0, 0);
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if (primescreen) {
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printValue(voltage); oled.print(F(mV));
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printValue(power); oled.print(F(mW));
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printValue(current); oled.print(F(mA));
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printValue(capacity / 1000); oled.print(F(mAh));
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} else {
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printValue(minvoltage); oled.print(F(SEP)); printValue(maxvoltage); oled.print(F(mV));
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printValue(mincurrent); oled.print(F(SEP)); printValue(maxcurrent); oled.print(F(mA));
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}
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oled.switchFrame();
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// a little delay
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delay(100);
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}
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// writes a register value to the INA219
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void writeRegister(uint8_t reg, uint16_t value) {
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TinyI2C.start(INA_ADDR, 0);
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TinyI2C.write(reg);
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TinyI2C.write((value >> 8) & 0xff);
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TinyI2C.write(value & 0xff);
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TinyI2C.stop();
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}
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// reads a register from the INA219
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uint16_t readRegister(uint8_t reg) {
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uint16_t result;
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TinyI2C.start(INA_ADDR, 0);
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TinyI2C.write(reg);
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TinyI2C.restart(INA_ADDR, 2);
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result = (uint16_t)(TinyI2C.read() << 8) | TinyI2C.read();
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TinyI2C.stop();
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return(result);
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}
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// writes inital configuration and calibration values to the INA
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void initINA() {
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writeRegister(CONFIG_REG, INA_CONFIG);
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writeRegister(CALIB_REG, INA_CALIB);
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}
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// read sensor values from INA219
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void updateINA() {
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voltage = (readRegister(VOLTAGE_REG) >> 1) & 0xfffc;
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current = readRegister(CURRENT_REG);
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if (current > 32767) current = 0;
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//power = readRegister(POWER_REG) * 20;
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}
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// prints 5-digit value right aligned
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void printValue(uint16_t value) {
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uint32_t counter = value;
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if (counter == 0) counter = 1;
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while (counter < 10000) {
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oled.print(SPACE);
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counter *= 10;
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}
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oled.print(value);
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}
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