Published September 25, 2020 © GPL3+

ATtiny13-Based, Key-Controlled Simple Dimmer

A tiny dimmer with corrected output for resistive loads. Controlled with 3 keys and showing current value on 8 tiny colored LEDs.

BeginnerFull instructions provided5 hours1,738

ATtiny13-Based, Key-Controlled Simple Dimmer

Things used in this project

Hardware components

Microchip Technology microchip - ATtiny13

74hc164

Triac

Software apps and online services

Microchip Studio

Story

Based on this project, I made a general purpose dimmer for incandescent bulbs or soldering irons with these advantages:

Key controlled: There are 3 keys for up, down and turning the load on/off.
8 LEDs to indicate the percentage of power.
Corrected output, so the light/heat of load is linear based on the current dimmer value.
Saving the value to eeprom to remember the values after reset.

Due to low pin counts of ATtiny13, the LEDs are connected using 74HC164 shift register. This model doesn't have a buffer register so it needs two pins to drive. one less pin than the popular 74HC595.

The input keys are read using a single ADC channel.

The power supply is a well known transformerless, capacitor based one.

Warning: This module is not isolated form mains. it should be kept in a proper plastic casing. The shift register library is platform independent and can be used for any ANSI-C based microcontroller.

The display

Code

#define KEY_DN		0
#define KEY_UP		1
#define KEY_SET		2
#define KEY_NO		3

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>

#include "aux_source.h"
#include "shiftreg.h"
uint8_t	dim_data;
bool deviceOn = true;
const uint16_t Dimmers[8] = { 0, 253, 369, 468, 531, 631, 850, 1000 };

int main()
{
	init_IO();
	dim_data = eeprom_read_byte(0);
	if (dim_data > 7)	dim_data = 7;
	tsr_shiftOut((1 << (dim_data + 1)) - 1);
	_delay_ms(250);
	while(1)
	{
		uint8_t  key = ReadKeys();
		if (deviceOn)
		{
			if (key != KEY_NO && key != KEY_SET)
			{
				if (key == KEY_DN)
				{
					if (dim_data > 0)	dim_data--;
				}
				else if (key == KEY_UP)
				{
					if (dim_data < 7)	dim_data++;
				}
				tsr_shiftOut((1 << (dim_data + 1)) - 1);
				eeprom_write_byte(0, dim_data);
				_delay_ms(100);
			}
		}
		if (key == KEY_SET)
		{
			deviceOn = !deviceOn;
			if (deviceOn)	tsr_shiftOut((1 << (dim_data + 1)) - 1);
			else			tsr_shiftOut(0);
			_delay_ms(800);
		}
	}
}



void sup_delay(uint16_t del)
{
	while (del--)
	{
		_delay_us(10);
	}
}

ISR(INT0_vect)
{
	if (deviceOn)
	{
		if (dim_data != 7)
		{
			//wait according to the Dimming table
			sup_delay(Dimmers[dim_data]);
			//fire triac
			PORTB |= (1 << PORTB0);
			_delay_us(30);
			PORTB &= ~(1 << PORTB0);
		}
		else
		{
			PORTB |= (1 << PORTB0);
			_delay_us(30);
			PORTB &= ~(1 << PORTB0);
		}
	}
}

#include "aux_source.h"

void init_IO()
{
	//B0 for triac fire, B3,B4 for shift register control
	DDRB	= (1 << DDB0) | (1 << DDB3) | (1 << DDB4);
	
	//pull-up the ADC
	PORTB	|= (1 << PORTB2);
	ADMUX	= (1 << ADLAR) | 1;
	DIDR0	= (1 << ADC1D);
	ADCSRA	= (1 << ADEN) | (1 << ADSC) | 5;
	while (!(ADCSRA & (1 << ADIF))) ;
	ADCSRA	|= (1 << ADIF);
		
	//enable external interrupts for both edges
	MCUCR	= 1;
	GIMSK	= (1 << INT0);
	sei();	
}


uint8_t ReadKeys()
{	
	ADCSRA	|= (1 << ADSC);
	while (!(ADCSRA & (1 << ADIF))) ;
	ADCSRA	|= (1 << ADIF);
	return ((ADCH * 3 + 80) / 256) ;
}

#include "shiftReg.h"


uint8_t tsr_buff[DAT_SZ_BYTE] = { 0 };


void tsr_initIO(void)
{
	CLK_DAT_LATCH_OUT_INIT;
	CLK_OUT_LO;
	DAT_OUT_LO;
	LATCH_OUT_LO;
}

void tsr_shiftBuffer(void)
{
	uint8_t j = 0;
	
	while (j < DAT_SZ_BYTE)
	{
		tsr_shiftOut(tsr_buff[j]);
		j++;
	}
	
}

void tsr_shiftOut(uint8_t tsr_var)
{
	uint8_t i = 0b10000000;
	LATCH_OUT_LO;
	while (i != 0)
	{
		if (tsr_var & i)	DAT_OUT_HI;
		else			DAT_OUT_LO;
		CLK_DELAY;
		CLK_OUT_HI;
		CLK_DELAY;
		CLK_OUT_LO;
		CLK_DELAY;
		i	= i >> 1;
	}
}

void tsr_latchOut(void)
{
	LATCH_OUT_HI;
}

void sr_setBit(uint32_t srBuffBit, bool srBuffVal)
{
	uint8_t q = srBuffBit/8;
	uint8_t r = srBuffBit%8;
	if(srBuffVal)	tsr_buff[q] |= (1<<r);
	else					tsr_buff[q] &=~(1<<r);
}

#ifndef __SHIFTREG_H__
#define __SHIFTREG_H__

#include <avr/io.h>
#include <util/delay.h>

#define CLK_DAT_LATCH_OUT_INIT		DDRB	|= (1 << DDB3) | (1 << DDB4)

#define CLK_OUT_HI	PORTB	|= (1<<PORTB3)
#define CLK_OUT_LO	PORTB	&=~(1<<PORTB3)
#define CLK_OUT_TOG PINB	|= (1<<PINB3)
#define DAT_OUT_HI	PORTB	|= (1<<PORTB4)
#define DAT_OUT_LO	PORTB	&=~(1<<PORTB4)
#define LATCH_OUT_HI
#define LATCH_OUT_LO

#define DAT_SZ_BYTE	1
#define CLK_DELAY	


#define DAT_SZ_BYTE	1


extern uint8_t tsr_buff[DAT_SZ_BYTE];


void tsr_initIO(void);
void tsr_shiftOut(uint8_t tsr_var);
void tsr_latchOut(void);
void tsr_setBit(uint32_t srBuffBit, bool srBuffVal);
void tsr_shiftBuffer(void);


#endif

Credits

Amir Kazemi

4 projects • 3 followers

Material science engineering MSc nano material researcher

ATtiny13-Based, Key-Controlled Simple Dimmer

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

schematic

Code

Main.c

peripheral init

shift register library

shift register header

peripheral init header

Credits

Amir Kazemi

Comments

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ATtiny13-Based, Key-Controlled Simple Dimmer

ATtiny13-Based, Key-Controlled Simple Dimmer

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

schematic

Code

Main.c

peripheral init

shift register library

shift register header

peripheral init header

Credits

Amir Kazemi

Comments

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