Cora Z7 board disconnects every few minutes

[DavidD]

Cora Z7 board disconnects every few minutes.

I get the message:

[Labtools 27-2312] Device arm_dap_0 is no longer available.
Check cable connectivity and that the target board is powered up then
use the disconnect_hw_server and connect_hw_server to re-initialize the hardware target.
Use open_hw_target to re-register the hardware device.

 

Then I have to unplug and replug the USB to get it to be available again so that I can program the FPGA on the Cora Z7 from Vivado.

How can this "disconnect every few minutes problem on the Cora Z7 be fixed?

[JColvin]

Hi @DavidD,

There are a couple of likely culprits causing this issue.

One is a USB cable of insufficient quality or bad connection (bad connection also could happen if you are routing the cable though an already busy USB hub). The second could be inconsistent power, potentially from the USB cable (also an issue with a busy).

What I would personally be attempting to resolve this is to try both a different USB cable and USB port (I have had both fail on me before).

Let me know what you find out.

Thanks,
JColvin

[DavidD]

On 2/6/2024 at 10:19 AM, JColvin said:

Hi @DavidD,

There are a couple of likely culprits causing this issue.

One is a USB cable of insufficient quality or bad connection (bad connection also could happen if you are routing the cable though an already busy USB hub). The second could be inconsistent power, potentially from the USB cable (also an issue with a busy).

What I would personally be attempting to resolve this is to try both a different USB cable and USB port (I have had both fail on me before).

Let me know what you find out.

Thanks,
JColvin

Please provide the product ID of a USB cable that is known to work with this device. It did not come with a USB cable. So if your product is sensitive to the cable, then you need to provide a way of someone getting a cable that will work reliably. Otherwise, you need to fix your product to work with most USB cables.

Thanks for your help!

On 2/6/2024 at 10:19 AM, JColvin said:

Hi @DavidD,

There are a couple of likely culprits causing this issue.

One is a USB cable of insufficient quality or bad connection (bad connection also could happen if you are routing the cable though an already busy USB hub). The second could be inconsistent power, potentially from the USB cable (also an issue with a busy).

What I would personally be attempting to resolve this is to try both a different USB cable and USB port (I have had both fail on me before).

Let me know what you find out.

Thanks,
JColvin

 

[DavidD]

Also, I tried using an external 5v power supply with up to 4A of capability. Programming and running worked fine but did not help with the “disconnect every few minutes” issue

[JColvin]

Hello,

Digilent sells a compatible cable on our store here, https://digilent.com/shop/usb-a-to-micro-b-cable/, but in theory any micro-B cables that support USB 2.0 speeds should work fine. The two cables that I use daily at my desk don't have any branding marked on them. The benefit of buying/paying for shipping for the USB cable from Digilent would be that if you still experience disconnect issues is that it would quickly narrow down the possible points of failure.

I don't know when/where you purchased the Cora Z7 (I don't have access to such data), but it's my understanding that when purchasing an FPGA from Digilent, you can optionally choose to add the appropriate USB cable for free to the purchase (the button for that is directly below the price listing; example on the Basys 3 page here: https://digilent.com/shop/basys-3-artix-7-fpga-trainer-board-recommended-for-introductory-users/). This looks somewhat easy to miss though, so I'll submit that as feedback to the web team.

Thanks,
JColvin