PCF 8574 GPIO pins extension how to use with Blynk iot?

[PeteKnight]

You used the correct part number in your title (PCF8574) but the wrong one here…

@Huzefamaz1

PCF 8564

If you search the forum for the correct part number then there are a few topics…
https://community.blynk.cc/search?q=PCF8574

I’ve never personally used this particular extender/multiplexor, but I have used some alternatives…

Using the MCP23017 IO Expansion Board

This second post looks at expanding on the code used in post #1 to add a second daisy-chained MCP23017 to the first one. I2C addresses when using multiple boards As stated before, it’s possible to have up to 8 boards linked together, to give a total of 128 GPIO pins. If you feel that masochistic then I’ve added comments that allow you to see where blocks of code would need to be duplicated (and adjusted slightly in some cases) to increase the number of boards used. Each board MUST have a uni…

ESP8266 16-way relay board using 2x 74HC595 controllers

I saw this post from @Vitokhv recently and decided to order one of these boards and have a play around with it. Here’s a link to another supplier on AliExpress who’s selling the same board: The boards are basically an ESP8266 with two 74HC595 shift registers that allow the 16 onboard relays to be controlled via just 4 GPIOs. They seem to be available in versions that work with a 5v, 12v or 24v supply voltage, and the relays are supposed to be capable of switching up to 250v at 10A each. …

Pete.