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Communication between motherboard serial port and usb ftdi chip

helpdesk
#1

I am trying to communicate between a serial port on a motherboard and a usb ftdi chip.

The ftdi chip is plugged into a windows machine and is assigned the label COM3. I used putty to set the baud rate to 115200, 8 bit, no parity, no flow and 1 stop bit:

putty setup

putty_setup

The serial port on the motherboard has the standard pinout:

serial pinout

And I have the grounds connected and the rx/tx connections properly swizzled.

I am running ubuntu server 18.04.2 on the machine with the serial port and I am using tio to setup the serial port:

[email protected]:~$ sudo tio --baudrate 115200 --databits 8 --flow none --stopbits 1 --parity none /dev/ttyS0

But all I seem to be able to send/receive is gibberish:

putty output

putty_com3

tio output

So I have obviously missed something, but I am not sure what. If anyone has any ideas, I would appreciate the help.

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#2

Turns out I’m a moron and rs-232 and ttl serial aren’t the same, I need another chip:

https://lcsc.com/product-detail/RS232_MAXIM_MAX232CSE-T_MAX232CSE-T_C45119.html

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