ESP8266 Community Forum

- Fri Oct 16, 2015 7:19 am #31517 Dear lakid,

Thanks for the reply.

I am sorry for posting it here but I got this link from Mr. Kolban's book. Now I have posted the followup in the following link.
viewtopic.php?f=6&t=6032

Please look at it.

Thanking you,
Yours sincerely,
Shubham Jain

- Fri Oct 16, 2015 7:20 am #31518 Hi there,
A quick uber noob question for you, on Page 24 of the October version you mention GPIO 15 "should be low on boot and flash"! but on page 25 Diagram it's not connected at all. Should I just pull it low with a resistor?

Many thanks
W.

- Sat Oct 17, 2015 11:51 am #31600 Just downloaded to book.. looking to jump right in
Thanks for all the effort..

I will try to remember to post book corrections/questions here and
tech/project questions elsewhere

- Sat Oct 17, 2015 12:17 pm #31601 Noggin,
That's an excellent question ... thank you for that. There is theory and practice. Ive read through the theory and theory says that GPIO 15 should be low on boot. On page 54 there is what I understand to be the semantics for the 8 combinations of the three pins GPIO 0, GPIO 2 and GPIO 15. So the theory says that GPIO 15 should be pulled low by a resistor. However, the empirical reality seems to show that not being "necessary" for an unused connection to pin 15. Does that mean that it is internally pulled low by default? Does that mean that I am just being "lucky" in whether or not my ESP8266 boots correctly or not? That I don't know. However, your point is indeed well taken and I'll change the circuit diagram to illustrate GPIO15 being explicitly pulled low.

leftyleo,
Thanks for the kind words. Hopefully a lot more information to come in the future over time.

Neil

Free ESP8266 book available for download here.