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ESP32 schematic help
#1
I am not an electronic geek but have built a number of diy PCBs over the years.

Would like to build the ESP32 interface for glass/magnetic scales.

I figure I don't need the "clock out" or the probe/tach section.

This part of the schematic leaves me realising my inadequate knowledge.

Can anyone explain it to me? 

   
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#2
(01-20-2024, 12:19 AM)Greolt Wrote: I am not an electronic geek but have built a number of diy PCBs over the years.

Would like to build the ESP32 interface for glass/magnetic scales.

I figure I don't need the "clock out" or the probe/tach section.

This part of the schematic leaves me realising my inadequate knowledge.

Can anyone explain it to me? 

This is a 3-pin header for selection the scale supply voltage. You don't really need it for a DIY build.

Regards
Yuriy
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#3
Thanks Yuriy

I had pretty much come to that conclusion.

Just trying to get my head around the 5v/3.3v needs.

ESP32 needs 5v
Glass scale needs5v
74HC14 needs 3.3v

I have ordered a ESP32 WROOM but has not arrived.
Does that board have a 3.3v output available to power the 74HC14 ?

And I assume the 3.3v signal output from the 74HC14 is sufficient for the ESP32 inputs signal.

Really appreciate any help.
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#4
Yes, the ESP32 board has a 3.3v output that can be used for the 74HC14s. The header you highlighted is for the scale power. As you are using glass scales, you just need to run their Vcc lines from your source USB supply.
The 3.3v option is if you are running capacitive scales.

I have recently built this board (in the UK) and found problems with cheap Amazon ESP32's with regards to the Bluetooth function. It took 4 boards to find one that worked reliably (I ended up buying 5 in total, but as they were very cheap, this was more annoying than costly)

Dave
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#5
Thanks for the reply Dave.

I am making progress and have two different ESP32 boards.  One with 30 pins and another with 38 pins.  Both have flashed the firmware successfully.  Used the "flash download tool". 
Couldn't make head or tail of the "ESP-IDF development framework"

Now trying to get one glass scale hooked up to the bread board to confirm all is well.

Only looking to provide for three axis so I should get away with only one SN74HC14N chip.

Need to work out if the USB can provide enough power for scales and everything or it needs a 5v regulator circuit built into the PCB.

All hard work for an old retired carpenter's brain.  Smile
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#6
(02-01-2024, 08:33 AM)Greolt Wrote: Thanks for the reply Dave.

I am making progress and have two different ESP32 boards.  One with 30 pins and another with 38 pins.  Both have flashed the firmware successfully.  Used the "flash download tool". 
Couldn't make head or tail of the "ESP-IDF development framework"

Now trying to get one glass scale hooked up to the bread board to confirm all is well.

Only looking to provide for three axis so I should get away with only one SN74HC14N chip.

Need to work out if the USB can provide enough power for scales and everything or it needs a 5v regulator circuit built into the PCB.

All hard work for an old retired carpenter's brain.  Smile

I am using mine to run 3 glass scales. I am powering from a standard 2.1A USB phone adapter but not direct into the ESP32 board connector. I feed through a veroboard mounted USB socket to a 5v Vcc strip, which then feeds the ESP32 and the scales separately. It works fine.
Phone chargers are actually well regulated 5v supplies. Just make sure they have a good current rating (less than 1A probably won't be up to the job)

Flashing the board was OK, but the first couple of boards would not reliably boot up the bluetooth connection. Sometimes it would work but other times not (I did start a thread on this forum but no one provided any thoughts).
The board I am using flashed exactly the same but works every time.

Dave
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