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73 lines
2.0 KiB
C++
73 lines
2.0 KiB
C++
/**
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* @file
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* @Author Septillion (https://github.com/sseptillion)
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* @date 2016-05-20
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* @brief Example how to use buttonRead()
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*
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* Because of the quasi-bidirectional port on the PCF8574 it's
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* possible to use the same pin as input and output at the same time.
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*
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* For this, connect the LED (or other device) between Vcc and the pin and
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* a button between GND and the pin.
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*
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* In order to read the pin the output is shortly (460us @ normal I2C speed)
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* set high during the read. So only use devices that can handle the small break
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* in state. It's not visable for the human eye with a LED.
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*
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* buttonRead() can also be used for pins that are input only.
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*
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* In this example pin 0 of the PCF8574 (address 0x20) is used to blink a
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* LED but at the same time it can be used to toggle the onboard LED of
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* the Arduino.
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*
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* NOTE: The button will affect the LED on the same pin. The led will light up
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* no matter the set output state when you press the button.
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*/
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#include <PCF8574.h>
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#include <Wire.h>
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PCF8574 pcf20(0x20);
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const byte onboardLed = 13;
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const byte PcfButtonLedPin = 0;
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unsigned int blinkMillis;
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unsigned int buttonMillis;
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void setup() {
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Serial.begin(115200);
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pcf20.begin();
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pinMode(onboardLed, OUTPUT);
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}
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void loop() {
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static bool state;
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unsigned int currentMillis = millis();
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//Limit button read to 20 times a second
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//Fast enough for most buttons
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//but this way you don't have a dimmer output because it's blanked during button read
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//a read takes 460us t 16Mhz Arduino and normal I2C speed.
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if(currentMillis - buttonMillis >= 50){
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buttonMillis = currentMillis;
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if(state != pcf20.readButton(PcfButtonLedPin)){
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if(state){
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//toggle the LED
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digitalWrite(onboardLed, !digitalRead(onboardLed));
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}
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state = !state;
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}
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}
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//Lets blink the same output
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if(currentMillis - blinkMillis >= 500){
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//Update time
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blinkMillis = currentMillis;
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pcf20.toggle(PcfButtonLedPin);
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Serial.println(pcf20.read8(), BIN);
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}
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} |