How do I interface an ESP32 PICO D4 with a CP2102N?

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Sashvat

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Hello everyone, I am trying to make my own custom board for which I am thinking of programming the ESP 32 microcontroller via USB. I have seen the PICO D4 Development kit which uses a CP2102N but not sure how to use it. I am trying to keep my PCB as small as possible so I am thinking of using the QFN-20 package. Would like to know how to connect it to my MCU.

Here is the data sheet for the CP2102N-https://www.mouser.com/datasheet/2/368/cp2102n_datasheet-1634912.pdf

Thank you
 
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Here's a good start from the EEVBlog forum. This gets you the USB side (data and power).

On the microcontroller side, remember RX-->TX and TX-->RX (i.e., they are swapped.).

 
Visitor said:
This gets you the USB side (data and power).
Click to expand...
That appears to not use Vusb but a separate 5V supply. Actually, two - 5V and Vdd - how strange.

To the OP, the schematic for the Wemos Lolin ESP32 board is freely available.

Mike.
Edit, the modules are available from banggood for $5½.
Schematic.
 
Last edited:
Visitor said:
Here's a good start from the EEVBlog forum. This gets you the USB side (data and power).

On the microcontroller side, remember RX-->TX and TX-->RX (i.e., they are swapped.).

Click to expand...
Thanks, I am thinking of using the 20 pin QFN package but DTR is missing would that be a problem?
 
There is also a "Battery Charger Detect" function that is available. My project does use a battery. I am not able to understand its function. What does it do?
 
Sashvat said:
Thanks, I am thinking of using the 20 pin QFN package but DTR is missing would that be a problem?
Click to expand...
I think DTR is used to reset the processor when the software needs to talk to it. The QFN24 has DTR and is only 4x4mm.

Mike.
 
Sashvat said:
There is also a "Battery Charger Detect" function that is available. My project does use a battery. I am not able to understand its function. What does it do?
Click to expand...
Woops, sorry that is obviously a version with a battery. If you google ESP32 schematic, there are lots available.

Mike.
 
Pommie said:
I think DTR is used to reset the processor when the software needs to talk to it. The QFN24 has DTR and is only 4x4mm.

Mike.
Click to expand...
right, but the 3x3mm qfn 20 doesn't have DTR, I sometimes use an FTDI board without DTR, would that be ok for me? Is DTR necessary when dealing with UART?
 
The circuit above is designed to run off a single Lipo battery and charge it when the USB cable is plugged in. Will this do what you want?

Mike.
 
Pommie said:
The circuit above is designed to run off a single Lipo battery and charge it when the USB cable is plugged in. Will this do what you want?

Mike.
Click to expand...
Is it the circuit you shared? But I have a different battery charging IC not the tp4054
 
Visitor said:
Here's a good start from the EEVBlog forum. This gets you the USB side (data and power).

On the microcontroller side, remember RX-->TX and TX-->RX (i.e., they are swapped.).

Click to expand...
I see there is a DTR pin that is not used and is NC. Is that ok? So now If I follow this circuit (even with the QFN 20 package) then would it be fine?
 
If you look at both the schematic I posted and the one you did, they both use DTR along with RTS to toggle the EN line on the processor. So, I think you need the DTR line. Which battery charging IC do you have?

Mike.
 
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