GPIO pin assignments for EPC-R3720/UIO-4030

There are wikis that describe GPIOs for the EPC-R5710, but none for the EPC-R3720.
How are the GPIO pin assignments for the EPC-R3720 defined?


Hi, Please check the link below for UIO-4030 user guide on EPC-R3720 wiki page.
UIO-4030 - ESS-WIKI (

There is GPIO pin assignment information:

1 Like

Thanks for infomation! I had overlooked it.
Is DB9-5 GND?

echo 505 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio1/direction
echo 1 > /sys/class/gpio/gpio1/value

I have executed the above command and connected the buzzer to DB9-6 and DB9-5 (possibly GND) but no sound.
Am I doing something wrong?


Could you try to short DB9-1 and DB9-6 for testing? And check if the DB9-1(DI1) can read the 1 status of the DB9-6(DO1).

Hi @Jems_Cheng
DB9-1 can read 1 from DB9-6.
( I re-implemented it and it can read 1. sorry)

Dear advantech.
The test section is blank on Wiki, Did you test the GPIOs by lighting LEDs, etc.?
Did you just short DI and DO?

HI Kawahara ,

Thank you for your instruction and read attentively. It’s a typo on this UIO device testing page when we created the UIO device testing page.
Addationally , we already removed the blank section . and hope that it doesn’t inconvenience you too much.