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ESP-12 DHT22 sensor shield (My first PCB design).

PostPosted: Mon Feb 13, 2023 3:58 am
by aphlox
Hello,

I have designed a PCB to run an ESP-12F with DHT-22 temperature tumidity sensor on battery.

I have no experience on designing a PCB so If anyone can point out if there is a problem I'd highly appreciate it.

I wanted to reset from pin to be able to wake from deep sleep also from the switch. I don't know if that is possible.
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Re: ESP-12 DHT22 sensor shield (My first PCB design).

PostPosted: Mon Feb 13, 2023 4:59 am
by btidey
Main issue I see is that your reset switch will short GPIO16 (mormally high) to GND when pushed. You want o include a diode , preferably schottky between GPIO16 and reset to prevent the conflict.

I would also include an electrolytic capacitor e,g, 220uF on the regulated 3.3V regulator output.

The 10K pull down on GPIO15 for start up is marginal in my view. I like to use 4k7.

Re: ESP-12 DHT22 sensor shield (My first PCB design).

PostPosted: Mon Feb 13, 2023 5:41 am
by aphlox
btidey wrote:Main issue I see is that your reset switch will short GPIO16 (mormally high) to GND when pushed. You want o include a diode , preferably schottky between GPIO16 and reset to prevent the conflict.

I would also include an electrolytic capacitor e,g, 220uF on the regulated 3.3V regulator output.

The 10K pull down on GPIO15 for start up is marginal in my view. I like to use 4k7.


The direction of the current is from GPIO16 to GND when the switch is pressed so if I block the current with diode I think I will also be blocking the wake up signal from GPIO16 to RESET. And if the diode is placed other way around there is still a short between GPIO16 and GND.

Am I wrong?
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This one still shorts GPIO16 to GND when switch is pressed

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This one blocks GPIO16 signal

Re: ESP-12 DHT22 sensor shield (My first PCB design).

PostPosted: Tue Feb 14, 2023 7:29 am
by btidey
The correct second one doesn't block the GPIO16 signal. During wake up the GPIO16 pulses low and this will pull the reset line low through the diode.