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82 lines
2.1 KiB
Markdown
82 lines
2.1 KiB
Markdown
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# PCF8574
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Arduino library for PCF8574 - I2C IO expander
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# Description
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This library gives easy control over the 8 pins of a PCF8574 and PCF8574A chip.
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These chips are identical in behavior although there are two distinct address ranges.
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| TYPE | ADDRESS-RANGE |
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|:----|:----:|
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|PCF8574 | 0x20 to 0x27 |
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|PCF8574A | 0x38 to 0x3F |
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THe library allows to read and write both single pins or 8 pins at once.
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Furthermore some additional functions are implemented that are a little more
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playfull but still are useful.
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### Interface
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**PCF8574(deviceAddress)** Constructor with device address as parameter.
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**begin(val = 0xFF)** set the initial value for the pins and masks.
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**begin(sda, scl, val = 0xFF)** idem, for the ESP32 where one can choose the I2C pins
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What needs to be added in the future is a parameter to choose another Wire interface
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as some processors have multiple hardware Wire interfaces.
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----
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**read8()** reads all 8 pins at once. This one does the actual reading.
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**read(pin)** reads a single pin; pin = 0..7
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**value()** returns the last read inputs again, as this information is buffered
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in the class this is faster than reread the pins.
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----
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**write8(value)** writes all 8 pins at once. This one does the actual reading.
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**write(pin, value)** writes a single pin; pin = 0..7; value is HIGH(1) or LOW (0)
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**valueOut()** returns the last written data.
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----
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TODO
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**setButtonMask(mask)**
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**readButton8()**
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**readButton8(mask = 0xFF)**
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**readButton(pin)**
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----
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**toggle(pin)** toggles a single pin
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**toggleMask(mask)** toggles a selection of pins, if you want to invert all pins use 0xFF.
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**shiftRight(n = 1)** shifts output channels n pins (default 1) pins right (e.g. leds ).
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Fills the higher lines with zero's.
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**shiftLeft(n = 1)** shifts output channels n pins (default 1) pins left (e.g. leds ).
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Fills the lower lines with zero's.
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**rotateRight(n = 1)** rotates output channels to right, moving lowest line to highest line.
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**rotateLeft(n = 1)** rotates output channels to left, moving highest line to lowest line.
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**reverse()** revers the "bit pattern" of the lines, high to low and vice versa.
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# Operation
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See examples
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