ESP8266 Community Forum

- Mon Feb 18, 2019 7:56 am #80631 In a project I 'm buiding with ESP8266-12E, I want to connect a Nokia 5110 LCD.
I need 5 pins from the ESP.
I have used for other purposes a few of them (GPIO14,GPIO12, GPIO13, GPIO15, GPIO4, GPIO5).
Between RESET and GPIO16 I will add a diode for wake up from deep sleep.

So have been left free: ADC, CH_PD, TXD, RXD, GPIO0, GPIO2, CS0, MISO, GPIO9, GPIO10, MOSI, SCLK.
Can I use any of these or I have ro remove any of them from the list?

ESP8266-12E-free-pins.png (11.53 KiB) Viewed 3123 times

- Mon Feb 18, 2019 9:23 am #80633 CS0, MISO, GPIO9, GPIO10, MOSI, SCLK are used for the ESP8266 access to the Flash chip holding the code. Generally the advice is not to use those pins.

https://github.com/esp8266/Arduino/sear ... ype=Issues

But take a look at the following.
https://github.com/esp8266/Arduino/pull/5489

https://github.com/espressif/esp8266-rt ... HSPI_Slave

https://www.google.com/search?q=hspi_sl ... e&ie=UTF-8

- Mon Feb 18, 2019 10:16 am #80635 Ok, they are removed from the list, so this is what remains:
ADC, CH_PD, TXD, RXD, GPIO0, GPIO2
I can use any of these ones?

- Mon Feb 18, 2019 11:13 am #80637

ADC, CH_PD, TXD, RXD, GPIO0, GPIO2
I can use any of these ones?

No, only TXD, RXD, GPIO0 and GPIO2 are GPIO's, the others aren't.
But special care has to be taken with those GPIO's since they're also used to program the ESP (you'll have to make sure they are properly pulled up or down at boot).

Please note that there are also a lot of nice and cheap OLED and TFT displays that use I2C which only need 2 GPIO's.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.