ESP8266 Community Forum

- Thu Jul 06, 2017 4:55 pm #68002

There doesn't seem to be a definitive source for proper connection of the ESP8266.

Sure there is ! This Wiki page is there for almost 3 years :
wiki/doku.php?id=esp8266_gpio_pin_allocations

That's this website which is a 3rd-party website.
It is unfortunate Espressif's own website is not quite user-friendly.

- Thu Jul 06, 2017 4:58 pm #68003

Most of the tutorials on the internet do not show any pull-up for GPIO0 and GPIO2 and RESET pins.

Yes, the web is full of nonsense.

Maybe so, but due to the lack of proper English language documentation by Espressif there were a lot of people who went at it on their own in the beginning.
They got it to work.
I am grateful to those pioneers who shared their information.

- Thu Jul 06, 2017 6:27 pm #68007

That's this website which is a 3rd-party website.
It is unfortunate Espressif's own website is not quite user-friendly.

I totally agree. Their documentation sucks. Compare their chip with any other established chip producer with a similar product and you will find that Espressif has only a small fraction of the information you normally would find. But the cost of the modules also are a fraction of the cost of comparable products.

Please keep in mind that most manufactures of components are not really interested in the hobby market. And while there are people where my hobby label doesn't apply I'm sure that most of them are not relying on Internet blogs for the core of their information.

I am a professional electronic hardware designer and have been for more than 30 years. For the most part I know what I am doing. I know what I have to look for when it comes to the hardware. What questions need to be answered, how to find those answers. But I am a hobbyist when it come to the ESP8266 because I am using it for my own home projects. And because software is something I am relatively inexperienced with.

I have designed one product based on the ESP-12 module at work close to a year ago. Unfortunately we haven't had a programmer available to do the software. Too busy on other projects. But if I had questions I'm sure they would be answered by Espressif. Because I am the kind of customer they really want. A manufacture that will use their product in the 1000s (minimum), not hobbyist quantities.

- Fri Jul 07, 2017 11:08 am #68036 Following is my experience and measurements on ESP-12F, although I think the ESP-12E is identical in this regard. Disclaimer, I have no argument with those who want to put an external pull up on GPIO 0 and 2. However, I do not think this is necessary for a successful boot particularly if those pins are not wired to external logic.

During boot these 2 pins are connected via internal pull ups to Vd and these have a value of about 30K ohms. After the boot phase the internal pull ups are removed and they are in an input floating condition unless the program puts them into some other mode.

This can be seen by putting a load resistance to ground on those pins and resetting. With say a 39K load to ground one gets around 2V during boot which is interpreted as a high and boot still succeeds. If one uses 10K then the internal pull up means there is only about 0.8V during boot which then fails.

A pull down is needed on GPIO15 and must be sufficiently low to sink the internal pull up to a low logic level (say < 4.7K)