Voltmeter ATtiny OLED Arduino (30V Max)

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Voltmeter ATtiny85 Arduino OLED

Simple Voltmeter Max 30V Using ATtiny OLED Arduino – The ATtiny85 is a family of ATMEGA microcontrollers from the MicroChip company (previously Atmel).

It only has 8 pin. This microcontroller has more than enough capabilities to make devices.

The specifications for Attiny85 are:

  • Program Memory Type Flash
  • Program Memory Size (KB) 8
  • CPU Speed ​​(MIPS/DMIPS) 20
  • EEPROM data (bytes) 512
  • Capture/Compare/PWM (CCP) 0
  • Max 8 Bit Digital Timers 2
  • Number of ADCs 0
  • ADC Channels 4
  • Max ADC Resolution (bits) 10
  • Number of Comparators 1
  • temp. Range Min. -40
  • temp. Range Max. 85
  • Operation Voltage Max.(V) 5.5
  • Operation Voltage Min.(V) 1.8
  • Pin Count 8
  • Low Power No

Today I am trying to implement ADC in Attiny85 to measuring voltage from 0V to 30V DC.

To be able to read from 0-30V I used a voltage divider resistor.

From the results of this voltage division, I convert it to a voltage value that will be displayed to the OLED.

Wiring

Now please look at the following picture and follow the wiring.

Voltmeter ATtiny OLED Arduino (30V Max)


Code

Please copy the following program and paste it into Arduino Ide. 

/*
   This basic code from : Pong game by Andy Jackson - Twitter @andyhighnumber
   Edited by chippiko.com
   Volt Meter V0.1
*/

#include "font6x8AJ.h"

#define DIGITAL_WRITE_HIGH(PORT) PORTB |= (1 << PORT)
#define DIGITAL_WRITE_LOW(PORT) PORTB &= ~(1 << PORT)

// Defines for OLED output
#define SSD1306_SCL   PORTB4  // SCL, Pin 4 on SSD1306 Board - for webbogles board
#define SSD1306_SDA   PORTB3  // SDA, Pin 3 on SSD1306 Board - for webbogles board
#define SSD1306_SA    0x78  // Slave address

char buff[10];
String stringVal;


void ssd1306_init(void) {
  DDRB |= (1 << SSD1306_SDA); // Set port as output
  DDRB |= (1 << SSD1306_SCL); // Set port as output

  ssd1306_send_command(0xAE); // display off
  ssd1306_send_command(0x00); // Set Memory Addressing Mode
  ssd1306_send_command(0x10); // 00,Horizontal Addressing Mode;01,Vertical Addressing Mode;10,Page Addressing Mode (RESET);11,Invalid
  ssd1306_send_command(0x40); // Set Page Start Address for Page Addressing Mode,0-7
  ssd1306_send_command(0x81); // Set COM Output Scan Direction
  ssd1306_send_command(0xCF); // ---set low column address
  ssd1306_send_command(0xA1); // ---set high column address
  ssd1306_send_command(0xC8); // --set start line address
  ssd1306_send_command(0xA6); // --set contrast control register
  ssd1306_send_command(0xA8);
  ssd1306_send_command(0x3F); // --set segment re-map 0 to 127
  ssd1306_send_command(0xD3); // --set normal display
  ssd1306_send_command(0x00); // --set multiplex ratio(1 to 64)
  ssd1306_send_command(0xD5); //
  ssd1306_send_command(0x80); // 0xa4,Output follows RAM content;0xa5,Output ignores RAM content
  ssd1306_send_command(0xD9); // -set display offset
  ssd1306_send_command(0xF1); // -not offset
  ssd1306_send_command(0xDA); // --set display clock divide ratio/oscillator frequency
  ssd1306_send_command(0x12); // --set divide ratio
  ssd1306_send_command(0xDB); // --set pre-charge period
  ssd1306_send_command(0x40); //
  ssd1306_send_command(0x20); // --set com pins hardware configuration
  ssd1306_send_command(0x02);
  ssd1306_send_command(0x8D); // --set vcomh
  ssd1306_send_command(0x14); // 0x20,0.77xVcc
  ssd1306_send_command(0xA4); // --set DC-DC enable
  ssd1306_send_command(0xA6); //
  ssd1306_send_command(0xAF); // --turn on oled panel
}

void ssd1306_xfer_start(void) {
  DIGITAL_WRITE_HIGH(SSD1306_SCL);  // Set to HIGH
  DIGITAL_WRITE_HIGH(SSD1306_SDA);  // Set to HIGH
  DIGITAL_WRITE_LOW(SSD1306_SDA);   // Set to LOW
  DIGITAL_WRITE_LOW(SSD1306_SCL);   // Set to LOW
}

void ssd1306_xfer_stop(void) {
  DIGITAL_WRITE_LOW(SSD1306_SCL);   // Set to LOW
  DIGITAL_WRITE_LOW(SSD1306_SDA);   // Set to LOW
  DIGITAL_WRITE_HIGH(SSD1306_SCL);  // Set to HIGH
  DIGITAL_WRITE_HIGH(SSD1306_SDA);  // Set to HIGH
}

void ssd1306_send_byte(uint8_t byte) {
  uint8_t i;
  for (i = 0; i < 8; i++)
  {
    if ((byte << i) & 0x80)
      DIGITAL_WRITE_HIGH(SSD1306_SDA);
    else
      DIGITAL_WRITE_LOW(SSD1306_SDA);

    DIGITAL_WRITE_HIGH(SSD1306_SCL);
    DIGITAL_WRITE_LOW(SSD1306_SCL);
  }
  DIGITAL_WRITE_HIGH(SSD1306_SDA);
  DIGITAL_WRITE_HIGH(SSD1306_SCL);
  DIGITAL_WRITE_LOW(SSD1306_SCL);
}

void ssd1306_send_command(uint8_t command) {
  ssd1306_xfer_start();
  ssd1306_send_byte(SSD1306_SA);  // Slave address, SA0=0
  ssd1306_send_byte(0x00);  // write command
  ssd1306_send_byte(command);
  ssd1306_xfer_stop();
}

void ssd1306_send_data_start(void) {
  ssd1306_xfer_start();
  ssd1306_send_byte(SSD1306_SA);
  ssd1306_send_byte(0x40);  //write data
}

void ssd1306_send_data_stop(void) {
  ssd1306_xfer_stop();
}

void ssd1306_setpos(uint8_t x, uint8_t y)
{
  if (y > 7) return;
  ssd1306_xfer_start();
  ssd1306_send_byte(SSD1306_SA);  //Slave address,SA0=0
  ssd1306_send_byte(0x00);  //write command

  ssd1306_send_byte(0xb0 + y);
  ssd1306_send_byte(((x & 0xf0) >> 4) | 0x10); // |0x10
  ssd1306_send_byte((x & 0x0f) | 0x01); // |0x01

  ssd1306_xfer_stop();
}

void ssd1306_fillscreen(uint8_t fill_Data) {
  uint8_t m, n;
  for (m = 0; m < 8; m++)
  {
    ssd1306_send_command(0xb0 + m); //page0-page1
    ssd1306_send_command(0x00);   //low column start address
    ssd1306_send_command(0x10);   //high column start address
    ssd1306_send_data_start();
    for (n = 0; n < 128; n++)
    {
      ssd1306_send_byte(fill_Data);
    }
    ssd1306_send_data_stop();
  }
}

void ssd1306_char_f6x8(uint8_t x, uint8_t y, const char ch[]) {
  uint8_t c, i, j = 0;
  while (ch[j] != '\0')
  {
    c = ch[j] - 32;
    if (c > 0) c = c - 12;
    if (c > 15) c = c - 6;
    if (c > 40) c = c - 6;
    if (x > 126)
    {
      x = 0;
      y++;
    }
    ssd1306_setpos(x, y);
    ssd1306_send_data_start();
    for (i = 0; i < 6; i++)
    {
      ssd1306_send_byte(pgm_read_byte(&ssd1306xled_font6x8[c * 6 + i]));
    }
    ssd1306_send_data_stop();
    x += 6;
    j++;
  }
}


// Arduino stuff - setup
void setup() {
  ssd1306_init();
  ssd1306_fillscreen(0x00);
  pinMode(A1, INPUT);
}

// Arduino stuff - loop
void loop() {
  // The lower case character set is seriously compromised because I've had to truncate the ASCII table
  // to release space for executable code - hence lower case y and w are remapped to h and / respectively.
  // There is no z in the table (or h!) as these aren't used anywhere in the text here and most of the
  // symbols are also missing for the same reason (see my hacked version of font6x8.h - font6x8AJ.h for more detail)
  ssd1306_char_f6x8(0, 0, "   DC VOLTMETER V1");
  ssd1306_char_f6x8(0, 1,  "---------------------");

  tampilTegangan();
}

void tampilTegangan() {

  //readVal normal nilai arduino
  int readVal = analogRead(A1);
  float val = readVal * 30.0 / 1024.0; //30.0 is maximum voltage read

  stringVal =  String(val, 1);
  stringVal.toCharArray(buff, 5);
  ssd1306_char_f6x8(0, 3, "Voltage");
  ssd1306_char_f6x8(97, 3, buff);
  ssd1306_char_f6x8(120, 3, "V");

  delay(10);
}

Now, make new tab and rename to font6x8AJ.h. Copy this code and paste to it. 

/*
 * SSD1306xLED - Drivers for SSD1306 controlled dot matrix OLED/PLED 128x64 displays
 *
 * @file: font6x8.h
 * @created: 2014-08-12
 * @author: Neven Boyanov
 * 
 * Hacked by andy jackson to allow two games (originally by webboggles.com) to 
 * fit onto an ATTiny85 at the same time - hence several characters are missing
 * and a couple have been moved to limit the amount of software remapping required
 * to map ASCII values onto locations in this array.
 *
 * Source code available at: https://bitbucket.org/tinusaur/ssd1306xled
 *
 */

// ----------------------------------------------------------------------------

#include <avr/pgmspace.h>

// ----------------------------------------------------------------------------

/* Standard ASCII 6x8 font */
static const uint8_t ssd1306xled_font6x8 [] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // sp
/*
  0x00, 0x00, 0x00, 0x2f, 0x00, 0x00, // !
  0x00, 0x00, 0x07, 0x00, 0x07, 0x00, // "
  0x00, 0x14, 0x7f, 0x14, 0x7f, 0x14, // #
  0x00, 0x24, 0x2a, 0x7f, 0x2a, 0x12, // $
  0x00, 0x62, 0x64, 0x08, 0x13, 0x23, // %
  0x00, 0x36, 0x49, 0x55, 0x22, 0x50, // &
  0x00, 0x00, 0x05, 0x03, 0x00, 0x00, // '
  0x00, 0x00, 0x1c, 0x22, 0x41, 0x00, // (
  0x00, 0x00, 0x41, 0x22, 0x1c, 0x00, // )
  0x00, 0x14, 0x08, 0x3E, 0x08, 0x14, // *
  0x00, 0x08, 0x08, 0x3E, 0x08, 0x08, // +
  0x00, 0x00, 0x00, 0xA0, 0x60, 0x00, // ,
  */
  0x00, 0x08, 0x08, 0x08, 0x08, 0x08, // -
  0x00, 0x00, 0x60, 0x60, 0x00, 0x00, // .
  0x00, 0x3C, 0x40, 0x30, 0x40, 0x3C, // w in place of /
  //0x00, 0x20, 0x10, 0x08, 0x04, 0x02, // /
  0x00, 0x3E, 0x51, 0x49, 0x45, 0x3E, // 0
  0x00, 0x00, 0x42, 0x7F, 0x40, 0x00, // 1
  0x00, 0x42, 0x61, 0x51, 0x49, 0x46, // 2
  0x00, 0x21, 0x41, 0x45, 0x4B, 0x31, // 3
  0x00, 0x18, 0x14, 0x12, 0x7F, 0x10, // 4
  0x00, 0x27, 0x45, 0x45, 0x45, 0x39, // 5
  0x00, 0x3C, 0x4A, 0x49, 0x49, 0x30, // 6
  0x00, 0x01, 0x71, 0x09, 0x05, 0x03, // 7
  0x00, 0x36, 0x49, 0x49, 0x49, 0x36, // 8
  0x00, 0x06, 0x49, 0x49, 0x29, 0x1E, // 9
  0x00, 0x00, 0x36, 0x36, 0x00, 0x00, // :
/*
  0x00, 0x00, 0x56, 0x36, 0x00, 0x00, // ;
  0x00, 0x08, 0x14, 0x22, 0x41, 0x00, // <
  0x00, 0x14, 0x14, 0x14, 0x14, 0x14, // =
  0x00, 0x00, 0x41, 0x22, 0x14, 0x08, // >
  0x00, 0x02, 0x01, 0x51, 0x09, 0x06, // ?
  0x00, 0x32, 0x49, 0x59, 0x51, 0x3E, // @
 */
  0x00, 0x7C, 0x12, 0x11, 0x12, 0x7C, // A
  0x00, 0x7F, 0x49, 0x49, 0x49, 0x36, // B
  0x00, 0x3E, 0x41, 0x41, 0x41, 0x22, // C
  0x00, 0x7F, 0x41, 0x41, 0x22, 0x1C, // D
  0x00, 0x7F, 0x49, 0x49, 0x49, 0x41, // E
  0x00, 0x7F, 0x09, 0x09, 0x09, 0x01, // F
  0x00, 0x3E, 0x41, 0x49, 0x49, 0x7A, // G
  0x00, 0x7F, 0x08, 0x08, 0x08, 0x7F, // H
  0x00, 0x00, 0x41, 0x7F, 0x41, 0x00, // I
  0x00, 0x20, 0x40, 0x41, 0x3F, 0x01, // J
  0x00, 0x7F, 0x08, 0x14, 0x22, 0x41, // K
  0x00, 0x7F, 0x40, 0x40, 0x40, 0x40, // L
  0x00, 0x7F, 0x02, 0x0C, 0x02, 0x7F, // M
  0x00, 0x7F, 0x04, 0x08, 0x10, 0x7F, // N
  0x00, 0x3E, 0x41, 0x41, 0x41, 0x3E, // O
  0x00, 0x7F, 0x09, 0x09, 0x09, 0x06, // P
  0x00, 0x3E, 0x41, 0x51, 0x21, 0x5E, // Q
  0x00, 0x7F, 0x09, 0x19, 0x29, 0x46, // R
  0x00, 0x46, 0x49, 0x49, 0x49, 0x31, // S
  0x00, 0x01, 0x01, 0x7F, 0x01, 0x01, // T
  0x00, 0x3F, 0x40, 0x40, 0x40, 0x3F, // U
  0x00, 0x1F, 0x20, 0x40, 0x20, 0x1F, // V
  0x00, 0x3F, 0x40, 0x38, 0x40, 0x3F, // W
  0x00, 0x63, 0x14, 0x08, 0x14, 0x63, // X
  0x00, 0x07, 0x08, 0x70, 0x08, 0x07, // Y
  0x00, 0x61, 0x51, 0x49, 0x45, 0x43, // Z
  /*
  0x00, 0x00, 0x7F, 0x41, 0x41, 0x00, // [
  0x00, 0x55, 0x2A, 0x55, 0x2A, 0x55, // 55
  0x00, 0x00, 0x41, 0x41, 0x7F, 0x00, // ]
  0x00, 0x04, 0x02, 0x01, 0x02, 0x04, // ^
  0x00, 0x40, 0x40, 0x40, 0x40, 0x40, // _
  0x00, 0x00, 0x01, 0x02, 0x04, 0x00, // '
*/
  0x00, 0x20, 0x54, 0x54, 0x54, 0x78, // a
  0x00, 0x7F, 0x48, 0x44, 0x44, 0x38, // b
  0x00, 0x38, 0x44, 0x44, 0x44, 0x20, // c
  0x00, 0x38, 0x44, 0x44, 0x48, 0x7F, // d
  0x00, 0x38, 0x54, 0x54, 0x54, 0x18, // e
  0x00, 0x08, 0x7E, 0x09, 0x01, 0x02, // f
  0x00, 0x18, 0xA4, 0xA4, 0xA4, 0x7C, // g
  0x00, 0x1C, 0xA0, 0xA0, 0xA0, 0x7C, // y (in place of h)
  //0x00, 0x7F, 0x08, 0x04, 0x04, 0x78, // h
  0x00, 0x00, 0x44, 0x7D, 0x40, 0x00, // i
  0x00, 0x40, 0x80, 0x84, 0x7D, 0x00, // j
  0x00, 0x7F, 0x10, 0x28, 0x44, 0x00, // k
  0x00, 0x00, 0x41, 0x7F, 0x40, 0x00, // l
  0x00, 0x7C, 0x04, 0x18, 0x04, 0x78, // m
  0x00, 0x7C, 0x08, 0x04, 0x04, 0x78, // n
  0x00, 0x38, 0x44, 0x44, 0x44, 0x38, // o
  0x00, 0xFC, 0x24, 0x24, 0x24, 0x18, // p
  0x00, 0x18, 0x24, 0x24, 0x18, 0xFC, // q
  0x00, 0x7C, 0x08, 0x04, 0x04, 0x08, // r
  0x00, 0x48, 0x54, 0x54, 0x54, 0x20, // s
  0x00, 0x04, 0x3F, 0x44, 0x40, 0x20, // t
  0x00, 0x3C, 0x40, 0x40, 0x20, 0x7C, // u
  0x00, 0x1C, 0x20, 0x40, 0x20, 0x1C, // v
 // 0x00, 0x3C, 0x40, 0x30, 0x40, 0x3C, // w
 // 0x00, 0x44, 0x28, 0x10, 0x28, 0x44, // x
 // 0x00, 0x1C, 0xA0, 0xA0, 0xA0, 0x7C // y
};

// ----------------------------------------------------------------------------

The result is:

Voltmeter ATtiny OLED Arduino (30V Max)


Now, please move the probe to another node of voltage. You will see change value of the voltage in OLED.

You can modify the code for the other project. Please add a polyfuse to protect your circuit from high current and voltage.

I hope this Voltmeter ATtiny articel is useful.