- Tue Feb 28, 2017 4:39 am
#63127
Hi Neil,
Thanks for you great book. it is a useful reference that gathers information from many places into one central document and as such it is very helpful
(*) I see in your post that Jan 2017 esp8266 edition is available, however in leanpub only November version is available.
I have few question regarding the ESP-01 available GPIO ports:
According to the documentation in your book and in other places, I see that ports of GPIO 0 and 2 are supposed to be held to High level after reset to allow proper function in normal mode.
GPIO 0 determines if the ESP is working in firmware update or normal mode after reset.
(*) What is the reason to set GPIO 2 to Hi During reset stage?
I understand that you recommend setting these pins as inputs in order to avoid accidental level conflict on these pins.
Assuming I will choose to use one or both of these port(s) as inputs, which I will connect to a sensor - I can't guarantee what the sensor level will be, and the ESP may need to boot, so I can't control the input level on that pin without added special HW that will tie this pin to high during reset.
In addition the ESP can reset itself due to spontaneous power drop or due to some soft reset.
* How would you approach this problem of using one or both of these ports correctly and assuring no damage will be done, and that the chip will power-up in normal working mode after reset unless I specifically want to program it with new FW?
Did you address this issue already?
* Could you please advise both for the GPIO pins as inputs and also when working with them as outputs?
I think that in addition to the answer here - it is worth to add this info to your book - as this is very basic usage that may be required from the ESP, specifically for the ESP01 that has only GPIO 0 and 2 as ports (also GPIO 1 and 3 - if we cancel the use of UART0).
Thanks,
Amit.