84 lines
3.1 KiB
Markdown
84 lines
3.1 KiB
Markdown
You can find updated version of documentation on my site [PCF8591](https://www.mischianti.org/2019/01/03/pcf8591-i2c-analog-i-o-expander/)
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Library to use i2c analog IC with arduino and esp8266. Can read analog value and write analog 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 PCF8591. Check that the PCF8591 folder contains `PCF8591\\.cpp` and `PCF8591.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 PCF8591 Analog input and analog output to digital converter 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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PCF8591(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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PCF8591(uint8_t address, uint8_t sda, uint8_t scl);
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```
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then IC as you can see in the image have 4 analog input and 1 analog output:
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So to read all analog input in one trasmission you can do (the value is from 0 to 255):
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```cpp
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PCF8591::AnalogInput ai = pcf8591.analogReadAll();
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Serial.print(ai.ain0);
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Serial.print(" - ");
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Serial.print(ai.ain1);
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Serial.print(" - ");
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Serial.print(ai.ain2);
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Serial.print(" - ");
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Serial.println(ai.ain3);
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```
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if you want read a single analog input or channel:
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```cpp
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int ana = pcf8591.analogRead(AIN0); // read analog 0
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```
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This IC have multiple type of read and you can use Analog input or analog channel (when you use single read analog input and channel are the same:
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For example to read the value of channel 0 in Two differential input you must do:
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```cpp
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int ana = pcf8591.analogRead(CHANNEL0, TWO_DIFFERENTIAL_INPUT); // read analog 0
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```
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If you want write an analog value you must do (the value is from 0 to 255):
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```cpp
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pcf8591.analogWrite(128);
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```
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Additional feature is to read a write voltage:
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For the calculation of voltage you must pass some parameter:
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- microcontrollerReferenceVoltage: get voltage from microcontroller voltage (only AVR no esp8266 for esp 3.3v fixed)
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- referenceVoltage: if microcontrollerReferenceVoltage false take this value
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The command are:
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```cpp
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void voltageWrite(float value, bool microcontrollerReferenceVoltage = true, float referenceVoltage = 5.0);
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float voltageRead(uint8_t analogPin, bool microcontrollerReferenceVoltage = true, float referenceVoltage = 5.0);
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```
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An examples is:
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```cpp
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pcf8591.voltageWrite(2.7); // 2.7Volts output
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delay(3000);
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float ana0V = pcf8591.voltageRead(AIN0); // Read voltage from analog 0
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Serial.println(ana0V);
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```
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For the examples I use this wire schema on breadboard:
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