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Document MCP23017 hardware bug and usage recommendations #1545

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Expand Up @@ -18,6 +18,15 @@ You will need to pick an I2C address in either of the above scenario's using the

![MCP23008 / MCP23017 I2C Address Map](https://github.com/andrethomas/images/raw/master/mcp230xx/i2c_address_map.png)


!!! warning "MCP23017 Hardware Bug"
Avoid using pins **GPA7** (pin 8) and **GPB7** (pin 28) as inputs.
Due to a design flaw in the MCP23x17 series, these pins are highly
sensitive to noise and can cause I2C bus corruption or false triggers.
In the latest version of the datashee, Microchip officially recommends
using them only as **outputs**.


### Supporting modes

Starting with Tasmota v12.4.0.2 there are two different modes to use MCP23xxx.
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