ESP32 Forum

Hi espressif,
( no hurry )

can we for test later do mod (dismantle/remove)
C11 ( 270pF) Chip Pin5+6
C12 (270pF) Chip Pin 7+8

to get full (without sensor function)
ADC1_PAD_GPIO37(Chip Pin 7)
ADC1_PAD_GPIO38 (Chip Pin 8)

then
ADC1_PAD_GPIO36 (Chip Pin 6)
ADC1_PAD_GPIO39 (Chip Pin 9)
is without C11,C12, Complications inside SoC?
I think inside no, but ask before do next time.

of course, we must solder there pads,(missing 37,38 pad on board)
have not found PAD for GPIO37, GPIO38
so my thinking is, for later test to remove the C11, C12 and docking there for wire.
ok?

second question: ( edit i have move to SDK )

thank you espressif!
best wishes
rudi

Dear Rudi,

C11 and C12 can be used as the sample capacitors for internal switching amplifier.

Application scenario 1: with C11 and C12

You can get a high-precision amplifier which can sense the tiny voltage between SENSOR_VP and SENSOR_VN.

Application scenario 2:without C11 and C12

You can get 4 channels of normal adc (SENSOR_VP SENSOR_CP SENSOR_CN SENSOR_VN ).

Please be noted that this is an either-or situation.

Any more questions, please let us know.

Thanks.

hi, I want to use GPIO37and GPIO38 as normal analog input pins what should I do?
can you guide me with few detailed steps?
thank you in advance.

@Espressif_Kelly is it necessary to remove this two capacitors to use GPIO37 & GPIO38 as normal analog input pins.
Thank you in advance.

Hi guys! (and maybe ladies?)

A bit of necroposting here. Could someone clarify:
1) Is it still valid for recent esp32 models, like d0wd which I use?
2) What is the range of these "tiny voltages"?
3) Do I understand correctly that vp should be used for +, and vn should be used for negative inputs? No needs to have a common ground then?
4) Why these pins ain't mentioned in the latest docs, like datasheets or design guidelines?

Thank you!

Viktrrrr wrote: ↑

Thu Aug 29, 2024 7:11 pm

1) Is it still valid for recent esp32 models, like d0wd which I use?
2) What is the range of these "tiny voltages"?
3) Do I understand correctly that vp should be used for +, and vn should be used for negative inputs? No needs to have a common ground then?
4) Why these pins ain't mentioned in the latest docs, like datasheets or design guidelines?

The idea is that the ADC could be used as a differential amp using those capacitors. In practice, it didn't really work that well, and as no one actually used it in a commercial product, we decided to deprecate it: it's not in the datasheet or supported by software and we don't test that feature anymore in new silicon.