ESP8266 Community Forum

- Tue Jan 19, 2016 2:15 am #39204 I've been trying to Google around and I've spent a good time on eBay looking for a GPIO-expander to use with my ESP8266. The requirements are quite simple: 3.3V I/O-level, control over I2C and it must be a board with interrupt-pin -- I cannot solder small stuff because of a nervous-system issue with my hands, so bare chips are a no-go, and the boards I found on Ebay that aren't 5V don't have the interrupt-pin available on them.

I would appreciate it if someone could point me in the right direction here, I'm kind of at a loss.

- Tue Jan 19, 2016 4:08 am #39207 EDIT - FORGET THIS NO LONGER AVAILABLE AS AN ASSEMBLED BOARD.
Hi, did some testing with the MCP23017 - it played nice and is still quite easy to get in 28 pin 0.1" pitch DIL package.
http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
If your using it with an ESP8266-01. GPIO 0 & 2 for SCL & SDA and GPIO 1 & 3 (Tx & Rx) for the interupts (Rx only if you only need 1 interupt and want to keep serial out for debuging).

- Tue Jan 19, 2016 7:16 am #39218 You could try the PCF8574.
It is digital IO
It supports I2C
It supports interrupt

It has one interrupt out port which has to be connected to one of the ESP6266 ports.
If one of the input ports has an interrupt, an interrupt on this generic interrupt line is created.
On the ESP8266 you have to poll the info from the chip to see which port generated this interrupt.
You can extend it to 8 devices, so you will have 64 ports max.

Easily obtainable at aliexpress: http://tinyurl.com/jv33vl9


You can also try the PCA9555
Datasheet: http://tinyurl.com/jga3e7g

It does the same thing as the PCF8574, but has 16 IO ports
Interrupts are working the same

Also obtainable at aliexpress: http://tinyurl.com/hwwswpf

Lua Timer - Use as many timers as you can fit in memory
https://github.com/MisterBennie/NodeMCU

- Tue Jan 19, 2016 8:57 am #39226 PCF8574 it's a easy one to use. I have used it also as a 8 Bit I/O Port expander on my Analog extension Board AN1, designed for the nEXT EVO Board.
Also used for some projects the MCP23017. Little bit more advanced, 16bit, etc,etc but again depends on what you want to do with. For a basic 8Bit I/O Port I found PCF8574 enough.

ESP8266 MPDMv4 AC MAINS Dimmer Home: http://esp8266-projects.com/2016/04/mpdmv4-mains-dimmerswitch-html/
Available on Tindie: https://www.tindie.com/products/nEXT_EVO1/universal-ac-mains-dimmer-mpdmv41/