ESTE: Automatic Dimmer with PWM and ADC

De MediaWiki do Campus São José
Revisão de 10h28min de 24 de novembro de 2015 por Katharine.sf (discussão | contribs) (→‎References)
Ir para navegação Ir para pesquisar

This experiment is part of this project.

This experiment is based on contents of this UFSC project.

Here we are going to build an experiment with an led and a LDR sensor and the same concepts seen on the Dimmer with PWM and ADC Script. Here we will use a potentiometer to turn 1 LED on and off, only if we need luminosity. To know how much luminosity(light) do we need in our surrounding we will use the LDR sensor, that indicates according to it's resistance, how should be the light intensity of the led. If our surrounding is to dark the specific led is turned on according to the potentiometer value. If it is bright enough, the led is turned off.

Pseudo code

Let's begin with a solution. The pseudo code (actual coding is up to you) is below: 

int main() {
    set_point = 127;
    duty_cycle = 0;
    while(1) {
        light = adc->read();
        if (light > set_point && duty_cycle >= 0)
            duty_cycle = 0;
        else if (light <= set_point && duty_cycle <= 255)
            duty_cycle = adc->read();
        pwm->write(duty_cycle);
        delay();
    }
    return 0;
}

The pseudo-code is self-explaining: an infinite loop reading the resistance value of the LDR Photoresistor (that indicates the ambient light), a composed conditional to switch on/off the LED according to the necessity of luminosity, and an ADC channel to which the potentiometer has been connected and determinates the light intensity of the LED.

Schematic

Schematic of the circuit

Part List

  • 1 LED
  • 1 220 ohm resistor to the led
  • 1 10k ohm resistor to the ldr photoresistor
  • 1 10k ldr photoresistor
  • 1 10k potentiometer
  • 1 Protoboard
  • 7 copper wires (tinned) or jumpers


Assembly

Assembly of the circuit

Solutions

  • [C - AVR]
  • [Arduino UNO]

Tools

  • AVR GCC and tools
  • Arduino IDE

References

Disponível em “https://wiki.sj.ifsc.edu.br/index.php?title=ESTE:_Automatic_Dimmer_with_PWM_and_ADC&oldid=97944”