Usb-uart


#1

hi
I want to connect to the board via usb-urat cable.
the UART output for dragon should have a voltage of 1.8v.

however, the output of most of uart-usb cables are 3.3v.

can I use the “Linker Mezzanine card for 96board” as a level sifter for the uart-usb of voltage 3.3 v?

http://linksprite.com/wiki/index.php5?title=Linker_Mezzanine_card_for_96board


#2

Hi @amati,

I have not tried it by myself but looking into the schematics of the Linker Mezzanine card is converting 1.8V UART for the serial console with level shifter on connector “UART”.

Pin1 - GND
Pin2 - VIN
Pin3 - TX
Pin4 - RX

The schematics is unclear whether it is converting to 3.3V or 5V UART, probably it is 3.3v, so please check the voltage with your multimeter first.

Please let me know if it is 3.3V.


#3

thanks for your reply.
actually, I dont have the linker. I want to order it if it is useful for me.

I want to measure the power consumption of board, so the minimal energy consumption of the peripheral boards(such as linker) it is important for me.
in addition, I was wondering if it is safe to use UART with output of 3.3 or 5 v with the Linker Mezannine card for Dragon 420c or not.


#4

There’s an example on the linksprite website (source code included) to show you how to do communicate with the UART on the board. The mezzanine comes with a jumper defaulted to 5v but you can easily move it to the 3.3v setting if you want.

http://learn.linksprite.com/project/uart-communication/


#5

Hi @amati,

I confirmed that it is able to change the voltage of the UART and other connectors between 5v or 3.3v by moving the jumper pin JP9.

As @vchong mentioned, it is sold with the jumper on 5V side as a default.