bluetooth problem with esp32-S3 custom board

iceMan806
Posts: 9
Joined: Tue Sep 20, 2022 4:50 am

bluetooth problem with esp32-S3 custom board

Postby iceMan806 » Tue Sep 20, 2022 6:04 am

hi dears...
I designed a custom esp32-S3 board and I program the board using the USB interface.
Almost most of the parts have been tested and worked without problems, recently I found out in the Bluetooth test that this part does not work at all.
I searched the forum, several people had my problem, but I did not find a clear answer as to where exactly the problem came from.
But one question stuck in my mind:
Does ESP32-S3 automatically check impedance matching? Because even if impedance matching is not observed, Bluetooth should be visible only at short distances (I programmed the Blufi example). But this does not happen and no device is visible.
The interesting point is that I have the same problem with ESP32-c3
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PCB layout is like this
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Spilz87
Posts: 5
Joined: Mon Oct 10, 2022 9:55 am

Re: bluetooth problem with esp32-S3 custom board

Postby Spilz87 » Mon Oct 10, 2022 9:58 am

hi

I had a similar issue.
I saw in your PCB you didn't had the capacitors close to the oscillator.

adding them solved my issue.

I hope it help you

Spilz87
Posts: 5
Joined: Mon Oct 10, 2022 9:55 am

Re: bluetooth problem with esp32-S3 custom board

Postby Spilz87 » Tue Oct 11, 2022 12:59 pm

you can look at this topic for impedance matching circuit
https://esp32.com/viewtopic.php?t=26106

the esp32C3 / S3 seems to be 35+j10 ohm
your antenna is usually 50 ohm

So the matching circuit seems to be 4.7pF / 1.8nH / 3.9pF (rounded to classic values)

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