Connecting USB to Reset RXD and TXD of ATMEGA328P

Other Hardware 3rd Party Boards
1

Hello,

Summary: Will connecting a USB cable directly from a PC to ATMEGA328P cause damage?

Details:
I am making a board with an ATMEGA328P and I would like to make it as small as possible by using a micro USB connector for battery charging and for programming.

I understand I need a programmer between PC USB and ATMEGA328P and plan to use this:
https://www.digikey.ca/product-detail/en/ftdi-future-technology-devices-international-ltd/TTL-232R-3V3/768-1015-ND/1836393

I am assuming that will work, please let me know if you disagree.

My main concern is what happens if someone plugs a USB cable directly from PC to 328P? Will that cause any problems?

This would probably be the connection in that case:
USB 328P
1 (5V) Vcc
2 (D-) TXD
3 (D+) RXD
4 DTR
5 (GND) GND

2

Update: I will actually probably use an UNO to program my board (connected through the micro USB port). Forgot the convert cable doesn't seem to handle the reset needed for the ATMEGA328P.

3

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4

Thank you for the reply.

I plan to use these connections for upload:

Only mentioned micro USB because I want to use that type of connector on my board to save on space and cost.

I would like to connect wires from UNO to micro USB plug and then plug it into micro USB socket on my board to DTR, RXD, TXD and power of ATMEGA328P.

What will happen if someone plugs that micro usb connector directly to a PC?

Will it cause damage if a PC is connected to DTR, TXD and RXD?

5

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6

Yes, the ATMEGA328P will be running at 3.3V

7

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8

It is very poor practice to use a USB cable for something other than USB; IMO you should either integrate the USB-serial adapter, so the USB cable will be connecting to a proper USB device on the other side, or you should use the USB connector for power only and have a separate connector for serial (I would use the 1x6 pin "FTDI" style header)

9

Thank you for the replies. This was just the push I needed to find a way to cram a tiny 5 pin header on my board for this:

TXD
RXD
DTR (reset)
5V
GND