Doctor Volt
Published © CC BY-SA

Interface VFD Tubes with an Arduino

VFD tubes are a good alternative to Nixie Tubes, especially in retro clock projects. Read about how they can be used with an Arduino.

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Interface VFD Tubes with an Arduino

Things used in this project

Hardware components

Arduino Nano R3
Arduino Nano R3
×1
IV-11 VFD Tubes
×4
Breadboard (generic)
Breadboard (generic)
×1
Jumper wires (generic)
Jumper wires (generic)
×1
TBD62783
Transistor Array with 8 channels
×2
HEF 4017
Decimal counter
×1
Step-Up Voltage Regulator - 30V
×1
Step-Down Voltage Regulator 1.5V
For the filaments
×1

Software apps and online services

Visual Studio Code Extension for Arduino
Microsoft Visual Studio Code Extension for Arduino

Story

Read more

Schematics

Schematic

Code

vfdtubes.ino

Arduino
#include "vfd.h";

// The setup() function runs once each time the micro-controller starts
void setup()
{
  Serial.begin(115200);
  vfd_init();
}

void loop()
{
	vfd_write("12.41.34");
};

vfd.cpp

Arduino
/*This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. 
To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/4.0/deed.en 
	  _____
	 |  e  |
	c|     |f
	 |_____|
	 |  d  |
	b|     |g
	 |_____|
		a    .p  */

#include "vfd.h"
#define SEG_DP (1 << 7)
#define SEG_A (1 << 6)
#define SEG_B (1 << 5)
#define SEG_C (1 << 4)
#define SEG_D (1 << 3)
#define SEG_E (1 << 2)
#define SEG_F (1 << 1)
#define SEG_G (1 << 0)

const byte numbers[] = {
	SEG_D, //-
	0,0,
	SEG_A + SEG_B + SEG_C + SEG_E + SEG_F + SEG_G, //0
	SEG_F + SEG_G, //1
	SEG_A + SEG_B + SEG_D + SEG_E + SEG_F, //2
	SEG_A + SEG_D + SEG_E + SEG_F + SEG_G, //3
	SEG_C + SEG_D + SEG_F + SEG_G, //4
	SEG_A + SEG_C + SEG_D + SEG_E + SEG_G, //5
	SEG_A + SEG_B + SEG_C + SEG_D + SEG_E + SEG_G, //6
	SEG_E + SEG_F + SEG_G, //7
	SEG_A + SEG_B + SEG_C + SEG_D + SEG_E + SEG_F + SEG_G, //8
	SEG_A + SEG_C + SEG_D + SEG_E + SEG_F + SEG_G, //9
};

const byte letters[] = {
	SEG_B + SEG_C + SEG_D + SEG_E + SEG_F + SEG_G, //A - 10
	SEG_A + SEG_B + SEG_C + SEG_D + SEG_G, //b - 11
	SEG_A + SEG_B + SEG_C + SEG_E, //C -12
	SEG_A + SEG_B + SEG_D + SEG_G + SEG_F, //d - 13
	SEG_A + SEG_B + SEG_C + SEG_D + SEG_E, //E - 14
	SEG_B + SEG_C + SEG_D + SEG_E, //F - 15
};
uint8_t chrtable[127];

// Port mask for the 7 segments + decimal point D5
#define PORT_C_MASK 0x3f //A0..A5
#define PORT_D_MASK (1 << 4) + (1 << 5) //D4..D5
// Multiplex
#define RESET 6 //D6
#define CLK 7 //D7
#define MULTIPLEX_MASK (1 << RESET) + (1 << CLK) 

void vfd_init() {
	//serial.println("-->vfd_init");
	DDRC |= PORT_C_MASK; 
	DDRD |= PORT_D_MASK + MULTIPLEX_MASK; 
	memcpy(chrtable+45, numbers, 13);
	memcpy(chrtable+65, letters, 6);
}

//Set the Segments (val) and devimal point (dpoint)
void write(uint8_t val, bool dpoint) {
	val = toupper(val);
	//Serial.println(val);
	PORTC &= ~PORT_C_MASK;
	PORTC = chrtable[val] & PORT_C_MASK;
	PORTD &= ~(PORT_D_MASK + MULTIPLEX_MASK);
	PORTD |= (chrtable[val] >> 2) & PORT_D_MASK;
	dpoint ? PORTD += (SEG_DP >> 2) : PORTD;
}

//Perform the multiplexing
void vfd_write(const char *val) {
	static uint8_t strpos, tube_nr = 1;
	static uint32_t _mills;
	uint32_t mills = millis();
	write((uint8_t)val[strpos], val[strpos + 1] == '.');

	//Multiplex
	if(mills >= _mills + 1){
		_mills = mills;
		if(val[strpos + 1] == '.'){
			strpos++; //Skip decimal point
		}
		strpos++;
		if(tube_nr++ >= NUMBER_OF_TUBES){
			tube_nr = 1;
			strpos = 0;
			bitSet(PORTD, RESET); //Get back to first tube
		};
		bitSet(PORTD, CLK); //enable next tube
	}
}

vfd.h

Arduino
/*This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. 
To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/4.0/deed.en */

#ifndef VFD_H
#define VFD_H

#include <Arduino.h>

//Enter the number of tubes you have here
#define NUMBER_OF_TUBES 6

void vfd_init();
void vfd_write(const char *val);

#endif

Credits

Doctor Volt

Doctor Volt

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