MCP23017 Library

Easy to use library for the MCP23017 connected to a Raspberry Pi.

Installation

i2c is required to be enabled in order to communicate with the chip. Also install these packages:

$ sudo apt-get install python-smbus i2c-tools

Usage

This library aims at being very similar to the RPi.GPIO library. At the moment it provides the following functions:

• start(address): Starts the library on the specified chip address.

• setup(pin, mode, pullupEnable): Writes direction (IN, OUT) to the specified pin. pullupEnable enables the internal 100k pullup resistor. Optional, and only works when setting a pin as an input. Valid values are PUHIGH and PULOW.

• output(pin, dir): Writes state (HIGH, LOW) to the specified pin.

• input(pin): Reads and returns pin state (True, False)

• puRead(bank): Reads and returns the pullup registers from both GPIO banks.

  • Valid parameter values: PU_A, PU_B, ALL or leave blank for a default graphic diagram of both banks.

• dirRead(bank): Reads and returns the direction registers from both GPIO banks.

  • Valid parameter values: BANK_A, BANK_B, ALL or leave blank for a default graphic diagram of both banks.

• latRead(bank): Reads and returns the latch registers from both GPIO banks.

  • Valid parameter values: LAT_A, LAT_B, ALL or leave blank for a default graphic diagram of both banks.

Please refer to the image below for the pin mapping.

Constant list

• MCP.OUT = 1
• MCP.IN = 0
• MCP.BANK_A = 0
• MCP.BANK_B = 1
• MCP.ALL = 2
• MCP.LAT_A = 3
• MCP.LAT_B = 4
• MCP.PU_A = 5
• MCP.PU_B = 6
• MCP.HIGH = 1
• MCP.LOW = 0
• MCP.PUHIGH = 1
• MCP.PULOW = 0

Pinout

Pins are mapped according to this diagram:

Code example

This example will set pin #2 as an input, with the pullup resistor enabled and #1 as an output. When the input goes high, pin #1 will also go high.

import mcp23017_lib as MCP

MCP.start(0x26)

MCP.setup(2, MCP.IN, MCP.PUHIGH)
MCP.setup(1, MCP.OUT)

while 1:
   if(MCP.input(2)):
      MCP.output(1, MCP.HIGH)
   else:
      MCP.output(1, MCP.LOW)

TODO list

• Do not use hardcoded i2c address
• Add pullup function
• Add raw write function
• Finish function documentation
• GPIO Zero Support

Contributors

Development:

• @ResonantWave

Debugging:

• @rafacouto

Contributing

• The code is licensed under the GPL V3
• Feel free to contribute to the code