I’m working on a project using a bare ESP8266-12F module and purchased your book, “Home_Automation_Using_ESP8266_V4” to get a better understanding. I like your book. It’s as clear and helpful as your tutorials that I have watched for years. In Part 0, your table of Best Pins to Use – ESP8266, is especially helpful. The project I’m working on requires a large number of inputs and I was hoping to use GPIO6 through GPIO11, but those pins are not mentioned in the table (other than to discouraging their use). Would you be able to provide any information about using those pins for inputs?
You can add a I/O expander
I hope it helps
Those pins on the ESP8266 are usually connected to the EPS8266 flash chip (GPIO6 to GPIO11). So, these are not recommended to use.
To have more GPIOs avialable, you can use an I/O expander as DK suggested.
I hope this helps.
Thank you for your help. This is my first attempt at using an ESP8266 so I was a bit naive about the number of usable I/Os that were available for the devices that I wanted to connect. I chose an ESP8266-12F bare module (not development board) to give myself the greatest flexibility for a final project.
Let me be more specific about my problem. I am trying to connect the following devices to the ESP8266:
Real Time Clock on I2C bus (GPIO4-5)
SD Card on SPI bus (GPIO12-15)
DS18B20 temperature sensors (1 GPIO)
3 digital inputs (These could be connected through an I/O expander)
3 DHT-22 sensors each on a single-bus (3 GPIOs) Am I correct, that they won’t work through an I/O expander?
I thought that since I was not connecting a flash chip, that GPIO6-11 would be available for my devices. The ESP8266-12F module that I purchased has pins GPIO6-11 labeled SCLK, MOSI, IO10, IO9, MISO, CS0 from top to bottom along the right side of the chip. (Looking from the front of the chip.)
Would it be possible to implement the SD Card on those pins instead of using GPIO12-15 and free those pins to use as digital i/O?
I welcome any other suggestions you have about my project.
The ESP8266-12F bare module still has the flash chip inside and the ESP8266 uses GPIOs6 to 11 to communicate with the chip via SPI communication, that’s why those pins are labeled as SPI pins.
The I/O expander allows you to control more digital outputs and inputs. I don’t think that the DHT sensors will work through an expander.
I would recommend using an ESP8266 development board instead of the chip, if you want to connect all those peripherals on the same board.