Introduction: Waveshare E-ink Display Precise Voltmeter (0-90v DC) With Arduino Nano
In this Instructable, I use a 2.9’’ Waveshare E-Paper display with an Arduino Nano, a voltage divider and an ADS1115 to display precise voltages up to 90 volts DC on the E-Paper Display.
This instructable combines these two previous projects:
- Arduino Volt Meter (0-100V DC) - Version 2 - https://www.instructables.com/Arduino-Volt-Meter-0...
- E-Paper Display Partial Refresh With Arduino - https://www.instructables.com/E-Paper-Display-Part...
Supplies
Supplies Used:
1 x Arduino Nano - https://amzn.to/2TiPaHY
1 x Waveshare display - https://amzn.to/33N1XrD
Breadboard and wires - https://amzn.to/2z0KmjH
USB Power Bank - https://amzn.to/3cEhk7Q
1 x ADS 1115 - 16 bit ADC - https://amzn.to/2XO82kD
1 x 1/4W (I suggest using 1W resistors though) 1% Resistors - 690k ohm - https://amzn.to/3dVGfEc
1 x 1/4W (I suggest using 1W resistors though) 1% Resistors - 10k ohm - https://amzn.to/3dVGfEc
Astro AI DM6000AR - https://amzn.to/3cJDVzR
9V Batteries - https://amzn.to/2zST1o0
CanadianWinters is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn fees by linking to Amazon.com and affiliated sites. By using these links, as an Amazon Associate I earn from qualifying purchases, even if you buy something else--and it won't cost you anything.
Step 1: Let's Connect the Components
I connected the components as follows:
Waveshare display:
Display <-> Arduino
BUSY <-> D7
RST <-> D8
DC <-> D9
CS <-> D10
DIN <-> D11
CLK <-> D13
GND <-> GND
VCC <-> 3.3V
ADS1115:
ADS1115 <-> Arduino
VCC <-> 5V
GND <-> GND
ADDR <-> GND
SCL <-> A5
SDA <-> A4
AIN0 <-> Voltage divider
For the voltage divider I used a 680Kohm and a 10Kohm resistors this time. I always measure the resistance values for better accuracy.
The calculations for the voltage divider are available at this spreadsheet that automates the calculations in case you want to use different resistor values: Link to Google Sheet . Please note that the file is not editable, you would need to download it or make a copy on your drive to be able to modify it.
Step 2: Code
The code for the display and for the ADC are quite big and there wouldn't be enough memory on the arduino if I used big characters on the screen.
To solve this, I converted the text to code by creating an image containing the text and then using this online tool to convert the image to code readable by the arduino: https://javl.github.io/image2cpp/
I still used some fonts and characters, but I only use a font containing numbers to display the battery voltage and the charge percentage in order to save memory.
This code displays the voltage of the battery and displays the charge percentage, assuming that at 90v the battery is charged and that at 0v the battery is completely flat. This can be modified to suit your needs.
// base class GxEPD2_GFX can be used to pass references or pointers to the display instance as parameter, uses ~1.2k more code
// enable or disable GxEPD2_GFX base class
#define ENABLE_GxEPD2_GFX 0
#include <GxEPD2_BW.h>
#include <GxEPD2_3C.h>
#include <Fonts/FreeMonoBold9pt7b.h>
#include <U8g2_for_Adafruit_GFX.h>
#include <Adafruit_ADS1015.h>
#include <Wire.h>
Adafruit_ADS1115 ads(0x48); //Adress of the ADC
#if defined(__AVR)
#define MAX_DISPLAY_BUFFER_SIZE 800 //
#define MAX_HEIGHT(EPD) (EPD::HEIGHT <= MAX_DISPLAY_BUFFER_SIZE / (EPD::WIDTH / 8) ? EPD::HEIGHT : MAX_DISPLAY_BUFFER_SIZE / (EPD::WIDTH / 8))
GxEPD2_BW<GxEPD2_290, MAX_HEIGHT(GxEPD2_290)> display(GxEPD2_290(/*CS=10*/ SS, /*DC=*/ 9, /*RST=*/ 8, /*BUSY=*/ 7));
#endif
U8G2_FOR_ADAFRUIT_GFX u8g2Fonts;
void setup()
{
Serial.begin(115200);
Serial.println();
Serial.println("setup");
ads.begin();
display.init();
u8g2Fonts.begin(display); // connect u8g2 procedures to Adafruit GFX
showbitmaps();
delay(500);
Serial.println("setup done");
}
void loop()
{
values();
delay(1000);
}
// 'charging-icon-c', 128x40px
const unsigned char Bat [] PROGMEM = {
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x01, 0xc0, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x0f, 0xc0, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x3f, 0x80, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
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0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x07, 0xff, 0x00, 0x00, 0x00, 0x0f, 0x87, 0xc7, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x3f, 0xff, 0x00, 0x00, 0x00, 0x0f, 0x87, 0xc7, 0xff, 0xff,
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0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x01, 0xff, 0xf0, 0x00, 0x00, 0x0f, 0x87, 0xc7, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x01, 0xff, 0x80, 0x00, 0x00, 0x0f, 0x87, 0xc7, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x01, 0xfe, 0x00, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x03, 0xf0, 0x00, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x03, 0xc0, 0x00, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x80, 0x07, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff
};
const unsigned char battext [] PROGMEM = {
// 'logisoso_epaper_volts_simple4, 128x145px
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x00, 0x1f, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xff, 0x1f, 0x1f, 0xff, 0xff, 0xff, 0xff, 0x80, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xff, 0x1f, 0x1f, 0xff, 0xff, 0xff, 0xff, 0x87, 0xf1, 0xf8, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xfe, 0x1f, 0x1f, 0xff, 0xf8, 0xff, 0xff, 0x8f, 0xf1, 0xf8, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x7e, 0x1f, 0x1f, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xf1, 0xf8, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x38, 0x00, 0x1f, 0xff, 0xf8, 0xff, 0xff, 0xc7, 0xe0, 0xf0, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xfe, 0x07, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x03, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x7f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x41, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x38, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xc3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x18, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc7, 0x18, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0x0e, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0x0e, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x71, 0xc3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0x0e, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x00, 0x07, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc7, 0x0e, 0x1f, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xf8, 0xff, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xf8, 0xff, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xf8, 0xff, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xff, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xff, 0xe3, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x8f, 0xff, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xcf, 0xff, 0xbf, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xc0, 0x7f, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfe, 0x00, 0x0f, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xfc, 0x31, 0x87, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x71, 0xc3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xf1, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x71, 0xc3, 0xff, 0xff, 0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x30, 0x07, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfe, 0x70, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xf0, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0x83, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xe0, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xe3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xfc, 0x00, 0x03, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc3, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x80, 0x0f, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xc3, 0xff, 0xff, 0xfd, 0xff, 0xff, 0x80, 0x03, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x00, 0x01, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0x3f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0xff, 0xff, 0xff,
0xff, 0xff, 0x1f, 0xff, 0x83, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xfe, 0x3f, 0xf0, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xfe, 0x3f, 0x00, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0x00, 0x00, 0x7f, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xf8, 0x01, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0x00, 0x0f, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xe0, 0x00, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0x80, 0x01, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x00, 0x0f, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc3, 0xfc, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xc0, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xfe, 0x03, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xf3, 0xff, 0xff, 0xfd, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc7, 0xfe, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0x00, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x07, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xf0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xcf, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0xff, 0xfc, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xe0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x3f, 0xfc, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x07, 0xfc, 0x9f, 0xff, 0xf8, 0xff, 0xff, 0xc0, 0x00, 0x00, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0x00, 0xfc, 0x1f, 0xff, 0xf8, 0xff, 0xff, 0x87, 0xfe, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xc0, 0x3e, 0x3f, 0xff, 0xf8, 0xff, 0xff, 0x8f, 0xff, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x78, 0x07, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xcf, 0xff, 0xbf, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x3f, 0x00, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x3f, 0xc0, 0x3f, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf9, 0x3f, 0xf8, 0x0f, 0xff, 0xf8, 0xff, 0xff, 0xf1, 0xe0, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xf8, 0x3f, 0xff, 0x0f, 0xff, 0xf8, 0xff, 0xff, 0xe1, 0xc0, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xfc, 0x7f, 0xff, 0xdf, 0xff, 0xf9, 0xff, 0xff, 0xc1, 0x80, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc7, 0x8e, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0x0e, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x87, 0x0e, 0x1f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc7, 0x1e, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0, 0x18, 0x3f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xe0, 0x38, 0x7f, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xf0, 0x78, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf9, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
//this function draws the images
void showbitmaps()
{
uint16_t bg = GxEPD_WHITE;
uint16_t fg = GxEPD_BLACK;
display.firstPage();
do
{
display.fillScreen(bg);
display.drawImage(battext, 0, 60, 128, 145, false,0, true); //text (y from bottom, x from left,height y, lenght x, reverse_color(true/false),rotate(0,1), transparency?(true/false))
display.drawImage(Bat, 0, 5, 128, 40, false,0, true); //battery icon
}
while (display.nextPage());
}
//this function calculates and prints the values on the display
void values()
{
float battV; // Battery Voltage
float perc; // Battery %
int calib = 7; // Value of calibration of ADS1115 to reduce error
float voltage =0; // used to store voltage value
float Radjust = 0.01437283477; // Voltage divider factor ( R2 / R1+R2 ) R1 ~690k and R2 ~10k
int16_t adc0; // 16 bits ADC read of input A0
adc0 = ads.readADC_SingleEnded(0);
voltage = ((adc0 + calib) * 0.1875)/1000;
battV = voltage/Radjust;
// Calculate battery %
perc = (battV/ 90) * 100; //we assume that the max voltage of the battery is 90v
//keep battery % 2-digit max to avoid display issues
if (perc >= 100){
perc = 99;
}
display.setRotation(1); // 0--> No rotation , 1--> rotate 90 deg
uint16_t bg = GxEPD_WHITE;
uint16_t fg = GxEPD_BLACK;
u8g2Fonts.setFontMode(1); // use u8g2 transparent mode (this is default)
u8g2Fonts.setFontDirection(0); // left to right (this is default)
u8g2Fonts.setForegroundColor(fg); // apply Adafruit GFX color
u8g2Fonts.setBackgroundColor(bg); // apply Adafruit GFX color
u8g2Fonts.setFont(u8g2_font_logisoso32_tn); // or u8g2_font_logisoso32_tr or u8g2_font_logisoso32_tn
display.setPartialWindow(203, 0, 100, 128); //(x from left, y from top, lenght x, height y)this sets a window for the values partial update
display.firstPage();
do
{
display.fillScreen(bg);
//Print battery voltage
u8g2Fonts.setCursor(205, 52);
u8g2Fonts.print(battV,1);
//Print battery %
u8g2Fonts.setCursor(205, 110);
u8g2Fonts.print(perc,0);
}
while (display.nextPage());
}<br>Step 3: Let's Test It Out :)
I am quite happy with the results.
I was able to test a number of voltages from about 9v to about 85v with minimum deviation (less than 0.2volts) from the actual voltage.
Once packaged into a nice enclosure this should make a nice little volt meter that can be read in very bright environments :).