mirror of
https://github.com/xreef/PCF8574_library.git
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81 lines
2.6 KiB
Markdown
81 lines
2.6 KiB
Markdown
Library to use i2c analog IC with arduino and esp8266. Can read and write digital value with only 2 wire (perfect for ESP-01).
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Tutorial:
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To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder PCF8574. Check that the PCF8574 folder contains `PCF8574\\.cpp` and `PCF8574.h`. Place the DHT library folder your `<arduinosketchfolder>/libraries/` folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.
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# Reef complete PCF8574 digital input and output expander with i2c bus.
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I try to simplify the use of this IC, with a minimal set of operation.
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Constructor:
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you must pas the address of i2c (to check the adress use this guide [I2cScanner](https://playground.arduino.cc/Main/I2cScanner))
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```cpp
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PCF8574(uint8_t address);
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```
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for esp8266 if you want specify SDA e SCL pin use this:
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```cpp
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PCF8574(uint8_t address, uint8_t sda, uint8_t scl);
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```
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You must set input/output mode:
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```cpp
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pcf8574.pinMode(P0, OUTPUT);
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pcf8574.pinMode(P1, INPUT);
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pcf8574.pinMode(P2, INPUT);
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```
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then IC as you can see in the image have 8 digital input/output:
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So to read all analog input in one trasmission you can do (even if I use a 10millis debounce time to prevent too much read from i2c):
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```cpp
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PCF8574::DigitalInput di = PCF8574.digitalReadAll();
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Serial.print(di.p0);
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Serial.print(" - ");
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Serial.print(di.p1);
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Serial.print(" - ");
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Serial.print(di.p2);
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Serial.print(" - ");
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Serial.println(di.p3);
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```
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if you want read a single input:
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```cpp
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int p1Digital = PCF8574.digitalRead(P1); // read P1
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```
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If you want write a digital value you must do:
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```cpp
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PCF8574.digitalWrite(P1, HIGH);
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```
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or:
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```cpp
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PCF8574.digitalWrite(P1, LOW);
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```
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You can also use interrupt pin:
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You must initialize the pin and the function to call when interrupt raised from PCF8574
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```cpp
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// Function interrupt
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void keyPressedOnPCF8574();
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// Set i2c address
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PCF8574 pcf8574(0x39, ARDUINO_UNO_INTERRUPT_PIN, keyPressedOnPCF8574);
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```
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Remember you can't use Serial or Wire on interrupt function.
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The better way is to set only a variable to read on loop:
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```cpp
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void keyPressedOnPCF8574(){
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// Interrupt called (No Serial no read no wire in this function, and DEBUG disabled on PCF library)
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keyPressed = true;
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}
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```
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For the examples I use this wire schema on breadboard:
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