ESP8266 Community Forum

- Tue Dec 29, 2015 12:04 pm #37384 Hi all , i hope you can help me on this project.
I wanna use my ESP-07 with arduino ide, and so i'm reading the quick start on this site.
I undestand that to use the ESP in a normal mode i need to boot up the ESP with:
ch-pd high
rst high
gpio15 down

IS it right?

After the boot ... the pins must be always on these set , or i can set them all on DOWN?

How can i use the gpio15 like a real gpio? In my project i need 8 gpios, i don't want use gpio0 (the flasher pin) , so i need to use gpio15. How can i use it if it must be always high?
Can i use the other gpios without limitation?

Thanks
Mirko

- Tue Dec 29, 2015 12:11 pm #37385 CH_PD and RST are not GPIO, they should stay pulled-up all the time.
GPIO15 needs to be pulled-down at power up or reset while GPIO2 and GPIO0 needs to be pulled-up.
After the boot, those 3 GPIOs can be used for something else.
If you still need more GPIOs, you can add an I2C GPIO expander, such MCP23017, attached to an I2C bus using 2 pins, for example the above GPIO2/GPIO0 with pullups.

- Tue Dec 29, 2015 12:23 pm #37386 Thanks for your answer, clear now.
Another quest ...
Considering that i wanna use the gpio2,gpio15,gpio0 after the boot , how can i set them only for the boot.
I need to use a transistor , or something else??
I would a situation where if i want a normal mode , i switch on the board ... and all is running (all gpios included). How can i set in UP the gpios only for the boot time?
thanks
Mirko

- Tue Dec 29, 2015 1:41 pm #37391 Simply by using resistors, pullups and pulldown according to the state mentioned above.
Then, after boot, you can use them as inputs or outputs as you wish.
Simply consider the boot state should be maintain as the priority, example : don't attach a LED to GND on GPIO0, it will act as a pulldown which will prevent the proper boot. If you wish having a LED connected to this GPIO0, you need to reverse the logic, connected to VCC and in your software, setting output to LOW will make that LED turning ON.