# GRMON is unable to attach to Arty A7 using UART debug link

**URL:** <https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197>\
**Category:** NOEL-V\
**Created:** [20 October 2021 21:28 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197 "2021-10-20T21:28:13Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![mmo](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@mmo](https://discourse.grlib.community/u/mmo)\
**Post date:** [20 October 2021 21:28 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/1 "2021-10-20T21:28:13Z")

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Hi,

in my setup GRMON (eval-3.2.13) is not able to attach to Arty A7 (rev.E) using UART debug link while printing “UART initialization failure, retrying” message. The Noel grlib b14267 is in use. The switch SW[3] is ON.

Would somebody confirm that it actually works (not necessarily with the same GRMON, grlib versions)?

Thanks,  
Martin

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**Author:** ![lcvisser](https://avatars.discourse-cdn.com/v4/letter/l/a5b964/32.png) [@lcvisser](https://discourse.grlib.community/u/lcvisser)\
**Post date:** [24 October 2021 11:55 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/2 "2021-10-24T11:55:27Z")

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I have managed to get a LEON3 running on a Arty A7-35T rev. E board. Not sure if the below applies to a NOEL too.

I used this command to connect:

```bash
$ grmon -digilent -freq 83

```

The `freq` flag should not be necessary, but I’ve noticed that some things work better if you do specify it. I did not have any of the switches on.

Note that you need the `ftdi` drivers that Digilent ships with the Adept software. The open source `libftdi` does not work.

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**Author:** ![hgrbz](https://avatars.discourse-cdn.com/v4/letter/h/8edcca/32.png) [@hgrbz](https://discourse.grlib.community/u/hgrbz)\
**Post date:** [8 August 2022 07:31 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/3 "2022-08-08T07:31:45Z")

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Hello. I have a nexys4-ddr fpga card. When I try to connect with the current version of GRMON, it gives a license problem and says I need to upgrade to the pro version. In which version did you try this?

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**Author:** ![mmo](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@mmo](https://discourse.grlib.community/u/mmo)\
**Post date:** [8 August 2022 20:48 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/4 "2022-08-08T20:48:06Z")

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Hi,

I downloaded the latest GRMON 3.2 Evaluation/Academic version (grmon-eval-64-3.2.17.tar.gz) from [Debug Tools](https://www.gaisler.com/index.php/downloads/debug-tools). Then I issued the command ./grmon -uart /dev/ttyUSB1 to connect successfully to Nexys A7 with Leon3.

Hope it helps.

Br,  
Martin

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**Author:** ![arvid](https://dub1.discourse-cdn.com/flex017/user_avatar/discourse.grlib.community/arvid/32/12_2.png) [@arvid](https://discourse.grlib.community/u/arvid)\
**Post date:** [16 August 2022 12:01 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/5 "2022-08-16T12:01:13Z")

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Hello,

GRMON Eval only supports designs using cores from GRLIB GPL and custom cores using the GRLIB vendor id VENDOR\_CONTRIB.

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**Author:** ![ciaociao](https://avatars.discourse-cdn.com/v4/letter/c/9fc29f/32.png) [@ciaociao](https://discourse.grlib.community/u/ciaociao)\
**Post date:** [8 February 2023 13:10 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/6 "2023-02-08T13:10:41Z")

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Hi,

I have the same issue. I’m using grmon 3.3 eval (grmon-eval-3.3.2.tar.gz / 23-Dec-2022) to attach Arty A7 100T FPGA board. The bitstream file contains NOELV RISCV Processor. I tried two debug links: uart and ethernet. The uart debug link is not working, while the ethernet debug link is working well.

1. attach the board with uart debug link (grmon -uart /dev/ttyUSB1)

2. attach the board with ethernet debug link(grmon -eth 192.168.0.51)

The greth, and ahbuart/ahbjtag can be found from the “info sys”, why it’s not possible to use the uart debug link?

 ![Screenshot from 2023-01-31 15-05-26](https://europe1.discourse-cdn.com/flex017/uploads/grlib/original/1X/24a772dc9a2e2295617c895b18ac0725f2db9f27.png)

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**Author:** ![fabio](https://avatars.discourse-cdn.com/v4/letter/f/f4b2a3/32.png) [@fabio](https://discourse.grlib.community/u/fabio)\
**Post date:** [10 February 2023 09:29 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/7 "2023-02-10T09:29:13Z")

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Hi ciaociao,  
Did you try using the jtag debug link?  
grmon -digilent

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<div class="post-metadata">

**Author:** ![ciaociao](https://avatars.discourse-cdn.com/v4/letter/c/9fc29f/32.png) [@ciaociao](https://discourse.grlib.community/u/ciaociao)\
**Post date:** [13 February 2023 08:43 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/8 "2023-02-13T08:43:33Z")

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Hi Fabio,  
I tried the jtag debug link today and it’s working well now.  
I tried this way last December and was told no digilent cables was found. So I abandoned jtag debug link for around two months until you told me.  
Many thanks

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<div class="post-metadata">

**Author:** ![fabio](https://avatars.discourse-cdn.com/v4/letter/f/f4b2a3/32.png) [@fabio](https://discourse.grlib.community/u/fabio)\
**Post date:** [13 February 2023 09:00 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/9 "2023-02-13T09:00:02Z")

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Hi ciaociao,  
Glad to hear that it’s now working for you!  
Vivado’s HW server keeps the JTAG drivers busy so it’s not possible to connect with GRMON with the digilent link when the Vivado HW server is running. So one needs to

1. Program the FPGA
2. Close the Vivado HW server
3. Connect with GRMON

Perhaps this was the issue you had in December?

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<div class="post-metadata">

**Author:** ![ciaociao](https://avatars.discourse-cdn.com/v4/letter/c/9fc29f/32.png) [@ciaociao](https://discourse.grlib.community/u/ciaociao)\
**Post date:** [14 February 2023 10:51 UTC](https://discourse.grlib.community/t/grmon-is-unable-to-attach-to-arty-a7-using-uart-debug-link/197/10 "2023-02-14T10:51:33Z")

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Hi Fabio,

It might be this issue, I’m not sure now. but thanks for your tips 😊