esp adaptor board?

[uxhamby]

On this style of esp adaptor board, am I safe to assume that the 3 resistors are gpio pull ups / downs for proper boot state?

I can't find a schematic of these boards anywhere, can anyone point me to one?

Thanks,

Brian H.

[Drum]

I am not aware if any official schematics and have seen several different versions of these, the ones I purchased have pads for an 1117 type voltage regulator which I would never use. You can see the traces under the white paint pretty easily, make your own schematic and be sure it is correct for the version of the board you have. You can also use a ohm meter to check.

[budman1758]

I have some of those boards.
R1 pulls GPIO2 up
R3 pulls CH-PD up
R2 is connected to the pad on the back and is unused unless you install a voltage regulator there.

[LisaM]

ESP32 boot states and GPIO pins are perfectly described here: https://github.com/espressif/esptool/wi ... -Selection

Cheers,

Lisa

[firozkhan]

Great Information.Well done

[TD-er]

If you want to make sure all boot state pins are correctly set, you can also use the ESP-12S.
These have the pull-up (ESP-EN, GPIO-0, GPIO-2) and pull-down (GPIO-15) set.
What does bother me is that these boards apparently have 2 resistors for pull-up/down, so I would expect GPIO-0 and -2 are not set.

[iron]

If you want to make sure all boot state pins are correctly set, you can also use the ESP-12S.
These have the pull-up (ESP-EN, GPIO-0, GPIO-2) and pull-down (GPIO-15) set.
What does bother me is that these boards apparently have 2 resistors for pull-up/down, so I would expect GPIO-0 and -2 are not set.

It is my understanding GPIO-O and GPIO-2 need to be pulled on demand only, no ?

-D

[TD-er]

If you want to make sure all boot state pins are correctly set, you can also use the ESP-12S.
These have the pull-up (ESP-EN, GPIO-0, GPIO-2) and pull-down (GPIO-15) set.
What does bother me is that these boards apparently have 2 resistors for pull-up/down, so I would expect GPIO-0 and -2 are not set.

It is my understanding GPIO-O and GPIO-2 need to be pulled on demand only, no ?

-D

See the documentation: https://espeasy.readthedocs.io/en/lates ... on-esp8266
Some pins should be pulled up or down or else the ESP will not boot properly.
A pull-up or pull-down resistor is meant to just slightly pull its value to some level, but it can be overriden by the ESP itself if needed.
Just make sure the level is well defined during boot.
This also means not all sensors can be connected to all GPIO pins. For example a sensor which pulls a pin to some level may prevent the ESP from booting when connected to one of these pins.

[iron]

If you want to make sure all boot state pins are correctly set, you can also use the ESP-12S.
These have the pull-up (ESP-EN, GPIO-0, GPIO-2) and pull-down (GPIO-15) set.
What does bother me is that these boards apparently have 2 resistors for pull-up/down, so I would expect GPIO-0 and -2 are not set.

It is my understanding GPIO-O and GPIO-2 need to be pulled on demand only, no ?

-D

See the documentation: https://espeasy.readthedocs.io/en/lates ... on-esp8266
Some pins should be pulled up or down or else the ESP will not boot properly.
A pull-up or pull-down resistor is meant to just slightly pull its value to some level, but it can be overriden by the ESP itself if needed.
Just make sure the level is well defined during boot.
This also means not all sensors can be connected to all GPIO pins. For example a sensor which pulls a pin to some level may prevent the ESP from booting when connected to one of these pins.

I understand all that very well. Just pointing out that ESP-EN pull up and GPIO-15 pull down are mandatory for operation and should be "hard wired". While GPIO-0 and GPIO-2 only need to be pulled conditionally therefore should not be hard wired thus there is not pads for those in that adapter.

-D