ESP32 specifiaction

frenkR
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ESP32 specifiaction

Postby frenkR » Sun Nov 29, 2015 11:09 am

is there any info on ADC I/O support? I mean channels, type of chanel, internal, external reference, speed?

ESPGURU
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8 channel ADC ...

Postby ESPGURU » Thu Dec 03, 2015 2:20 am

frenkR wrote:is there any info on ADC I/O support? I mean channels, type of chanel, internal, external reference, speed?
think we have 13 BIT, 8 channel, can measure 0..4 V in 0..4096 by setting atten 0,1,2,3

http://www.esp32.com/viewtopic.php?f=5&t=19&p=79&#p79
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kolban
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Re: ESP32 specifiaction

Postby kolban » Thu Jan 07, 2016 2:52 am

Isn't a range of 0-4095 12 bits?
Free book on ESP32 available here: https://leanpub.com/kolban-ESP32

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rudi ;-)
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Re: ESP32 specifiaction

Postby rudi ;-) » Thu Jan 07, 2016 3:51 am

kolban wrote:Isn't a range of 0-4095 12 bits?
adc_tune.png
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hope this helps

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rudi ;-)
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Re: ESP32 specifiaction

Postby rudi ;-) » Thu Jan 07, 2016 4:05 am

btw..
"..GURU" information is ok, have the same info from code..
but the info "range" 0, 4096 is wrong and i started practical with firmware and test like you see in video.
adc_info_bug.png
adc_info_bug.png (24.25 KiB) Viewed 19034 times

btw, we have up to 16 channel

:mrgreen:

hope now is clear
..
Last edited by rudi ;-) on Thu Jan 07, 2016 4:08 am, edited 1 time in total.
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ESP_Me-no-dev
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Re: ESP32 specifiaction

Postby ESP_Me-no-dev » Thu Jan 07, 2016 12:28 pm

I have found the ADC to be really bad.
Full range at max attenuation (0-4V) actually is 0-3V or a bit below VCC
In the middle of the scale (2048) voltage is actually above 2Volts which is way off of the expected 1.5V (half of full)
Same can be noticed throughout the range and attenuations.
Basically you can not do any real measurement using this ADC.
Observations done with two multimeters.

thereza
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Re: ESP32 specifiaction

Postby thereza » Fri Jan 08, 2016 9:46 pm

Actually, this isn't clear to me at all. When talking about the 'N-bits' of an ADC, it's commonly understood that you have a range of values from 0-(N^2-1) for a total of N^2 divisions (assuming non- 2s complement encoding). 13 bits would equal a range of 0 - 8191. If the range is truly 0-4096 then that doesn't make sense (from a hardware/implementation perspective), and at best it would be called '12-bit plus 1' or something.

Reza

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ESP_Me-no-dev
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Re: ESP32 specifiaction

Postby ESP_Me-no-dev » Sat Jan 09, 2016 12:08 am

Why are you guys going over those bits so much :)
It's really simple. 12 bits = 0 -> 4095 and those are actually 4096 steps, because 0 is a value as well.

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rudi ;-)
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Re: ESP32 specifiaction

Postby rudi ;-) » Sat Jan 09, 2016 2:02 am

me-no-dev wrote:
It's really simple. 12 bits = 0 -> 4095 and those are actually 4096 steps, because 0 is a value as well.

:mrgreen:
( fun! )

we have then 4096 steps? :mrgreen:

example: 1v in
atten= 0

1V / 4096 = 0,000244140625 V
we have then max value 4095 = ( ( 1V / 4096 ) * 4095 ) = 0,999755859375V

if we have 4095 steps :mrgreen:
1V / 4095 = 2,442002442002442e-4 V
we have then max value 4095 = ( (1V / 4095 ) * 4095 ) = 1V

..

btw
if we have value : 0
then
( ( 1 V / 4096 ) * 0 ) = 0
( ( 1 V / 4095 ) * 0 ) = 0

have a look : same here:
steps_in_adc.png
steps_in_adc.png (17.02 KiB) Viewed 18902 times

:mrgreen:

(/fun)

i allways calc

Value ?
Value : 4095
then 1 step = 1V / 4095

best wishes
rudi ;-)


btw
value 1023 same ( blue circle )
we have no 1 / 1024
we have max 1 / 1023

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rudi ;-)
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Re: ESP32 specifiaction

Postby rudi ;-) » Sat Jan 09, 2016 2:09 am

thereza wrote:.. 13 bits would equal a range of 0 - 8191. If the range is truly 0-4096 then that doesn't make sense (from a hardware/implementation perspective), and at best it would be called '12-bit plus 1' or something.

Reza
you are right.
the 13 bit is value range 0..8191

but we have range 0..4095.
so we have 12 bit adc.

'12-bit plus 1' there is no chance to get this in real :mrgreen:

nice talk, this fun!

think there is a description mistake in the code / understand mistake.
we have 1 / 1024 but we have not really to calculate the step 0
because value 0 = 0 V
our calc base is max value.
this is 12 bit, 4095
so i think ( hope )
1 / 4095 is the right
or
1 / 1023
and so on.

best wishes
rudi ;-)
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