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By daleschultz
Hi all,

I am relatively new to this world so I have a rather nooby question...

at ... e-overview
it states that pin labeled 14 "Can either be used as ESP8266 GPIO14 or I2C serial clock (SCL)."

My question is - do we have to do anything to prepare the pin to be used as a GPIO?
How will the board 'know' that the pin is now perhaps connected to a relay or LED?

Can we simply expect to do this?
The page goes on to say:
The lower part of the header breaks out one of the ESP8266’s serial UARTs. This serial port is used to program the thing, so be careful using it for other tasks.
This suggests that using GPIO7 and GPIO8 would interfere with serial communication... how can we know which ones are safe to use??

A project I am working on will need 7 outputs to drive 7 relays, so I am trying to work out which pins to use. There are 4 that seem to have no overlap with any other functionality (0, 4, 5 , 15)

GPIO12 and GPIO13 are also MISO and MOSI - if I am not using SPI, I hope I can use them.

GPIO16 is also the deep sleep wake up. I plan on providing power continuously so I don't see me needing to use a sleep mode (presumably to save battery power). Does pinMode(16,OUTPUT) force it to be used as an output and not a wake up input?