Any definitive wiring guide for an ESP-01 1M ?

[budman1758]

Sure letting GPIO2 flloat will certainly not heart the ESP, but will it be reliable in the long term?
I prefer rather spending time at start, than repairing stuff later.

Methinks you will be fine long term.

[soif]

Ok thanks for your experienced opinion.

so I will certainly end up ONLY wiring CH_PD to VCC + GPIO-0 10k pullup, if nobody else disapprove.

Any advice on the capacitor?
Is my 10uF tantalum one a good choice?
just in case (because I have no oscilloscope to check the power supply).

[soif]

BTW while searching for other esp related things, I found on this , which seems a reliable source:
http://arduino-esp8266.readthedocs.io/e ... ml#minimal

Minimal boot (for ESP12):


CH_PD + GPIO0 confirmed to be pull-up + ( GPIO15 pulldown should ceraintly be ignored, as it is NOT present on ESP01)

[Shardan]

A 10KOhm from Reset to 3.3V is always a good idea. Some ESP-01 have it in board some rely on the ESP8266's own "weak" pullup.

I'd always add a capacitor as near as possible to +3.3V and Gnd.
I reccomend to electrolytic or tantalum capacitors.
Use a ceramic type (X5R or X7R series). These MLCC capacitors have a much
better performance on high frequencies then other types. 100nF...1µF will do.

For the R3 (GPIO15 -> GND) .... GPIO15 must be pulled down to GND to start the firmware.
I won't ignore this......

[SophieDeziel]

I found this post (and the wonderful guide) using Google trying to find an answer to a pretty specific question:

To flash the ESP8266-01, I have found that some modules need the GPIO2 pin to be connected to VCC and some others can be left dangling, while in all cases GPIO0 must be connected to ground.

I'm trying to find the reason or a way to identify which modules need to have GPIO2 to be up at boot time to flash. Could it be because of some external factor like power source? I'll be very happy to contribute to the guide with this information.

[Shardan]

It is a somewhat specific problem with ESP-01:

There is a mess of versions, all called ESP-01. (V.1, V.2, V.3, ESP-01S and maybe more)
The types differ a bit with their internal circuits, some have pull-ups other versions miss and so on.

For my own circuits I tend to use external pullup resistors anyways.

Why?

Well, it does not hurt if you add a 10KOhm resistor in parallel to the internal pullup on the board if there is any.
On the other side it makes sure that every version works.

Sure you may connect CH_PD directly to Vcc - prefer a 10KOhm resistor anyways.
When switching power supply on or off voltage spikes may occur for example.
A resistor is a protection for the inputs in that case.

Together with this: Give RST a 10KOhm to Vcc and a capacitor 22µ...47µ to GND.
This keeps the chip on reset for a short moment after powering up. Just make it wait a bit for stable power line.
Even a good power supply is somewhat unpredictable when switched on/off.

You can leave GPIO2 floating, sure. But be aware that the internal on-chip pullup is "weak". External interferences
may influence the input - it needs a well defined "high" level for correct booting. If you really need a resistor depends
on your circuit anyways. If you drive a LCD 2004 display on GPIO 0/2 of an ESP-01 it is usually not necessary: Most display
driver boards have pullups built in

The study books say "don't leave any input floating" for a reason - reliability.
This on one side is pure theory. On the practical side any input involved in startup should have a pull-resistor.
That will give a good reliability for daily use (Besides things like filtering capacitors and such, obviously.... )

Regards

[grovkillen]

...

You're back!

[SophieDeziel]

Thank you so much Shardan!

Your explanations are super clear. Not only there is the "how" but also the "why". I'll follow your advices with the pull-up resistors and also the capacitor.