MCP23017

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Introduction

The number of GPIO pins on the ESP module can be expanded with a IO Expander. We will use the MCP23017 that provides 16 more pins that can be used as input or output. This way it becomes possible to control a 16 channel relay board.

Each individual pin can be used as either input or output.

Hardware

MCP23017DIP28.jpg

The MCP23017 needs to be connected through the I2C interface. This chip is compatible with 3V3 and it can be connected to the ESP without levelshifters..

Connections

 MCP23017 	ESP-01
 GND 	 	GND
 VCC    	VCC
 SDA		GPIO 0
 SCL		GPIO 2

Software

ESP Easy

Configuration depends on how you want to use a certain port on this device. Ports are numbered 1 to 16 (if you have a single MCP23017 connected)

Input

To have an input port act as an input switch device (just like with the default onboard GPIO pins) you need to edit a ESP Easy task and select the "MCP23017 input" device.

EasyConfigMCP.png

You then select the portnumber and additional configuration depending on the controller type. For Domoticz, you enter the IDX that was allocated by Domoticz for this virtual switch.

Portnumbering depends on the I2C address used:

A0: A1: A2: Address: Port range:
0 0 0 0x20 1 - 16
1 0 0 0x21 17 - 32
0 1 0 0x22 33 - 48
1 1 0 0x23 49 - 64
0 0 1 0x24 65 - 80
1 0 1 0x25 81 - 96
0 1 1 0x26 97 - 112
1 1 1 0x27 113 - 128

Optional settings

Use of value names

Output

You can control output pins on this chip with the following http command:

http://<ESP IP address>/control?cmd=mcpgpio,<pin>,0

http://<ESP IP address>/control?cmd=mcpgpio,<pin>,1