ESP8266 Community Forum

- Mon Mar 05, 2018 2:24 pm #74381 So I built a weather station around the ESP8266-07.

Please have a look at the design. I am interested in making sure that connections to the ESP are proper as far as pull ups/downs etc.

I tied GIPO16 to reset through R10 (100 ohms). I found some sources saying resistor required, others saying directly to ground. I can do any value including 0.

GIPO15 goes to ground through R6(10K). Some sources said 10K, others direct. IDK.

Sorry the schematic is a bit messy, its my first go at Eagle.

The .SCH file is attached for eagle users

A .PDF of the schematic follows for Non-eagle users.

Thanks for the help,

-Dave

SWSSCH2.5.pdf

You do not have the required permissions to view the files attached to this post.

- Mon Mar 05, 2018 4:56 pm #74388 GPIO15 has to be a logical low during reset / boot for it to run. There is an internal pull up of around 33 -40K which is active a that point. Although a 10K pull down will normally work OK it is a bit marginal given that an active low is supposed to be < 0.25Vcc. I would use 4.7K to be more certain.

- Mon Mar 05, 2018 6:54 pm #74391 What would happen if I ran GIPO15 right to ground without a resistor at all?

Thanks!

-Dave

- Mon Mar 05, 2018 8:02 pm #74393

What would happen if I ran GIPO15 right to ground without a resistor at all?

Maybe not quite so dramatic.

I have an LED-resistor connected to D15 and gnd on all my development boards. I get a bright flash for about 1/10th of a second on a reset. If this were shorted to ground there would be a lot more current than there should be. Just put in a resistor or buy a module that already has them, like the ESP-12S. I believe it also has the required pull-ups.

I would also add a couple of resistors on the I2C lines. Most modules include resistors but they are usually high in value and might not work well at faster speeds. Many people have success without them.