# GPIO pin assignments for EPC-R3720/UIO-4030 **URL:** \ **Category:** Technical Supports\ **Created:** [May 29, 2023, 4:02am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463 "2023-05-29T04:02:56Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Tetsuya\_Kawahara](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aim-linux.advantech.com/tetsuya_kawahara/32/476_2.png) [@Tetsuya\_Kawahara](https://forum.aim-linux.advantech.com/u/Tetsuya_Kawahara)\ **Post date:** [May 29, 2023, 4:02am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/1 "2023-05-29T04:02:56Z")
There are wikis that describe GPIOs for the EPC-R5710, but none for the EPC-R3720. [http://ess-wiki.advantech.com.tw/view/GPIO](http://ess-wiki.advantech.com.tw/view/GPIO) How are the GPIO pin assignments for the EPC-R3720 defined? Thanks. ---
**Author:** ![Jems\_Cheng](https://avatars.discourse-cdn.com/v4/letter/j/c57346/32.png) [@Jems\_Cheng](https://forum.aim-linux.advantech.com/u/Jems_Cheng)\ **Post date:** [May 29, 2023, 7:25am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/2 "2023-05-29T07:25:28Z")
Hi, Please check the link below for UIO-4030 user guide on EPC-R3720 wiki page. [UIO-4030 - ESS-WIKI (advantech.com.tw)](http://ess-wiki.advantech.com.tw/view/UIO-4030) ![image](https://us1.discourse-cdn.com/flex016/uploads/aim_linux/original/1X/8bec1e9e979a3af7951da00b8cb8caf25dbdd2f2.png) There is GPIO pin assignment information: ![image](https://us1.discourse-cdn.com/flex016/uploads/aim_linux/original/1X/114e3e10beb05c95d65bd2c733c99c4b79bba0ab.png) ---
**Author:** ![Tetsuya\_Kawahara](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aim-linux.advantech.com/tetsuya_kawahara/32/476_2.png) [@Tetsuya\_Kawahara](https://forum.aim-linux.advantech.com/u/Tetsuya_Kawahara)\ **Post date:** [May 29, 2023, 7:39am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/3 "2023-05-29T07:39:38Z")
Thanks for infomation! I had overlooked it. Is DB9-5 GND? ---
**Author:** ![Tetsuya\_Kawahara](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aim-linux.advantech.com/tetsuya_kawahara/32/476_2.png) [@Tetsuya\_Kawahara](https://forum.aim-linux.advantech.com/u/Tetsuya_Kawahara)\ **Post date:** [May 30, 2023, 3:05am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/4 "2023-05-30T03:05:32Z")
```auto 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? ![image](https://us1.discourse-cdn.com/flex016/uploads/aim_linux/original/1X/1ff6e0d68cbf056516a11e2a930ce1e3d78b850e.png) ---
**Author:** ![Jems\_Cheng](https://avatars.discourse-cdn.com/v4/letter/j/c57346/32.png) [@Jems\_Cheng](https://forum.aim-linux.advantech.com/u/Jems_Cheng)\ **Post date:** [May 30, 2023, 7:58am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/5 "2023-05-30T07:58:46Z")
Hi, 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). ---
**Author:** ![Tetsuya\_Kawahara](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aim-linux.advantech.com/tetsuya_kawahara/32/476_2.png) [@Tetsuya\_Kawahara](https://forum.aim-linux.advantech.com/u/Tetsuya_Kawahara)\ **Post date:** [May 30, 2023, 8:29am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/6 "2023-05-30T08:29:28Z")
Hi @Jems_Cheng DB9-1 can read 1 from DB9-6. ( I re-implemented it and it can read 1. sorry) ---
**Author:** ![Tetsuya\_Kawahara](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aim-linux.advantech.com/tetsuya_kawahara/32/476_2.png) [@Tetsuya\_Kawahara](https://forum.aim-linux.advantech.com/u/Tetsuya_Kawahara)\ **Post date:** [May 31, 2023, 1:15am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/7 "2023-05-31T01:15:49Z")
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? [http://ess-wiki.advantech.com.tw/view/UIO-4030](http://ess-wiki.advantech.com.tw/view/UIO-4030) ---
**Author:** ![phill.liu](https://avatars.discourse-cdn.com/v4/letter/p/a8b319/32.png) [@phill.liu](https://forum.aim-linux.advantech.com/u/phill.liu)\ **Post date:** [May 31, 2023, 9:05am UTC](https://forum.aim-linux.advantech.com/t/gpio-pin-assignments-for-epc-r3720-uio-4030/463/8 "2023-05-31T09:05:34Z")
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.