ESP8266 Developer Zone

Re: bizarre wave on GPIO0

2016-01-06T22:45:17+08:00

same phenomenon.
viewtopic.php?f=6&t=1485

Statistics: Posted by wakky — Wed Jan 06, 2016 10:45 pm

Re: bizarre wave on GPIO0

2015-11-21T06:27:39+08:00

Please watch the wave at the time of the reset, if you have an oscilloscope. Surely you are surprised.

Statistics: Posted by wakky — Sat Nov 21, 2015 6:27 am

Re: bizarre wave on GPIO0

2015-11-14T16:27:12+08:00

My circuit is very simple. That has only 5V to 3.3V voltage regulator, R, C, LED, SW and wire.
When I observed the wave, I could't believe the wave.
It is reasonable that you can't believe this wave.

Statistics: Posted by wakky — Sat Nov 14, 2015 4:27 pm

Re: bizarre wave on GPIO0

2015-11-14T16:21:36+08:00

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Statistics: Posted by wakky — Sat Nov 14, 2015 4:21 pm

Re: bizarre wave on GPIO0

2015-11-14T16:23:39+08:00

deleted

Statistics: Posted by wakky — Sat Nov 14, 2015 4:16 pm

Re: bizarre wave on GPIO0

2015-11-14T16:28:33+08:00

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Statistics: Posted by wakky — Sat Nov 14, 2015 4:14 pm

Re: bizarre wave on GPIO0

2015-11-14T05:21:17+08:00

Not sure why you're seeing the voltage go above 3.3 volt; probably parasitic capacitance and inductance is causing ringing close to the 27Mhz frequency.

Not the end of the world but I do think it is a bug because GPIO0 is also used as input during boot. Unfortunately it's baked in the boot ROM so we'll have to wait for the ESP32 to fix this

If the voltage overshoot causes problems you could add a resistor and a zener diode to clip it to 3.5 or so volts?

Statistics: Posted by joostn — Sat Nov 14, 2015 5:21 am

Re: bizarre wave on GPIO0

2015-11-13T23:50:28+08:00

AT command firmware output same bizarre wave at reset.

Statistics: Posted by wakky — Fri Nov 13, 2015 11:50 pm

Re: bizarre wave on GPIO0

2015-11-13T22:50:23+08:00

My chip's photo
I have 5 chips, and all chip's GPIO0's behavior is same.

All my friend said "Your oscilloscope is broken". But they confirmed bizarre wave.

Statistics: Posted by wakky — Fri Nov 13, 2015 10:50 pm

Re: bizarre wave on GPIO0

2015-11-13T22:39:21+08:00

Dear Espressif_Kelly
My friend observed that wave https://www.facebook.com/photo.php?fbid ... 912&type=3 .
Yellow wave is GPIO0's wave.
magenta wave is RESET's wave.

Yellow wave's behavior was as follows
(1)3.3V constant
(2)from -0.5V to 4.0V 26MHz wave.
(3)0.0V constant
(4)from -0.5V to 4.0V 26MHz wave.
(5)3.3V constant

I think that bootloader has bug.

Statistics: Posted by wakky — Fri Nov 13, 2015 10:39 pm

Re: bizarre wave on GPIO0

2015-11-13T19:23:06+08:00

Dear Wakky,

If you use 3.3V DC power supply, the peak to peak voltage of GPIO0 shoule be 3.3V.

Please double check if your oscilloscope has been correctly set.

Any more questions, please let us know.

Thanks.

Statistics: Posted by Espressif_Kelly — Fri Nov 13, 2015 7:23 pm

Re: bizarre wave on GPIO0

2015-11-12T08:47:30+08:00

The bootloader have a bug -- set GPIO0 as clock output. Bootloader v1.2 and v1.4(b) have same bug.

Statistics: Posted by wakky — Thu Nov 12, 2015 8:47 am

Re: bizarre wave on GPIO0

2015-11-07T09:36:26+08:00

Dear Espressif_Kelly
Frequency is 27.5MHz
https://www.facebook.com/photo.php?fbid ... =3&theater

> GPIO0 of ESP8266EX can output the clock frequency of the external cystal
I understood.

Why is the voltage from -1V to 5V over this GPIO0?
This voltage from -1V to 5V gives damege to my circuit.

Wave at download time is https://www.facebook.com/computerartisa ... 369391869/

Statistics: Posted by wakky — Sat Nov 07, 2015 9:36 am

Re: bizarre wave on GPIO0

2015-11-04T11:36:37+08:00

Dear Wakky,

GPIO0 of ESP8266EX can output the clock frequency of the external cystal(e.g. 26Mhz or 40MHz) by default.

Please check it by measuring the frequency of this bizarre wave.

Any more questions, please let us know.

Thanks.

Statistics: Posted by Espressif_Kelly — Wed Nov 04, 2015 11:36 am

Re: bizarre wave on GPIO0

2015-11-02T18:56:16+08:00

GPIO0 wave at download https://www.facebook.com/computerartisa ... 369391869/
and other man's report https://www.facebook.com/photo.php?fbid ... 912&type=3

Statistics: Posted by wakky — Mon Nov 02, 2015 6:56 pm

bizarre wave on GPIO0

2015-10-30T22:54:51+08:00

I observed bizarre wave on GPIO0 at the time of reset.
My circuit is most simile and use 3.3V DC.
What is the wave?

Statistics: Posted by wakky — Fri Oct 30, 2015 10:54 pm