Azure Sphere custom device noise issue

95504669 521

Hi, We use Azure sphere module in our custom device. Azure has to send some hex values by UART to another device after restart. But even if azure sends proper values, the other device receives extra unwanted hex values along with default values only when azure restarts. When the Azure has to send hex values without restart, there is no unwanted values received by other device.

Have tested using the waveform app with Azure Tx. Unwanted hex values are observed along with needed hex values. Please let me know how to fix this issue. Thank you.

LeelaRajeshSayana-MSFT 13,471 Reputation points

2023-07-26T23:20:39.1966667+00:00

Hello @95504669 , thank you for posting the question here. Is the issue in question encountered with using Azure Sphere Guardian module May I know if you have any specific processes in your custom application that are being executed either during the disconnection or the reconnection with the Azure service.
95504669 521 Reputation points

2023-07-28T06:37:10.9433333+00:00

I have tested this with Azure starter kit Rev2 but didnt face any issue.
With our custom device , we see extra bytes after restart of the device.
Currently after the External device update, we want to restart the azure to downlodd regular Azure Iot code. But during the restart the azure reruns the current external dfu application until it downloads the main Azure Iot code. At this time after the restart of azure, we see extra bytes on azure uart. No extra unwanted bytes are seen if there is no restart.
So we confirmed the restart caused this issue.
We have check using FTDI with Azure Tx and mostly its not visible by terminal.
We have confirmed the unwanted bytes by using oscilloscope and waveform app. The unwanted values will be or ÿ or something else.
How can we fix this issue? Thank you
95504669 521 Reputation points

2023-07-28T06:53:48.7433333+00:00

We have tested this with Azure starter kit Rev2 and we didnt face this issue.
Only with our custom board during the restart of azure we see extra unwanted bytes being sent from Azure along with our default uart data.
We confirmed this happens only after restarting the azure.
we currently have 2 seperate codes for external dfu and regular Azure Iot. So we need restart after the external dfu is done. But the restart causes some issue and adds extra bytes which will disrupt the dfu process.
How can i avoid this unwanted bytes. I have tried connecting a pullup resistor to azure Tx and 3.3V. Still couldnt fix this.
Connected a oscilloscope to azure Tx and confirmed the extra unwanted bytes using waveform app. This values are most of the time not visible by FTDI. The extra byte will be ÿ or or or something else.
Thank you.
Alistair Lowe 191 Reputation points Microsoft Employee

2023-08-02T21:19:39.0933333+00:00
Hello @95504669,

Could I please confirm some further details for clarity:

If you perform the exact same steps, you don't receive this issue on starter kit Rev2? (same application, same UART, same reset mechanism etc).

What module are you using? (the manufacturer and part number).

What mechanism are you using to perform the reset?

Does the extra byte occur immediately after reset or only after you configure the UART and start to send your desired data?

Which UART and pins are you using, and with what settings?

Are you using the HLCore or RTCore?

Could you please confirm you're following all guidance provided here, if using the HLCore: https://learn.microsoft.com/en-us/azure-sphere/app-development/uart?

Could you describe in more detail the sequence of events?

Please note that we also provide sample hardware schematics here: https://github.com/Azure/azure-sphere-hardware-designs/tree/main/P-MT3620RDB-1-7, however, if you're using a module, you may need to consult with the module manufacturer for their specific recommendations.

Many thanks
Alistair Lowe 191 Reputation points Microsoft Employee

2023-08-17T08:04:13.45+00:00

@95504669 Just checking in to see if you've been able to resolve this issue, or to refer you to the above questions should you require further support.

Many thanks
Alistair Lowe 191 Reputation points Microsoft Employee

2023-08-21T10:16:48.51+00:00

@95504669 Thank you for the update and I'm happy to hear you were able to resolve the issue. If possible we'd appreciate if you're able to mark your response as an answer (or post an answer is not) so that we can close-off this thread. Many thanks

2 answers

95504669 521 Reputation points

2023-08-21T10:12:17.5+00:00

Yes. We have the Tx Rx pin taken our custom board. We were using jumpers to connect Azure to external device. Once we soldered the TX Rx, it worked. Thank you.
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LeelaRajeshSayana-MSFT 13,471 Reputation points

2023-08-23T14:43:20.67+00:00

Hi @95504669 I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to accept the answer .

Issue:

After embedding Azure Sphere module in our custom device, the device receives extra unwanted hex values along with default values only when azure restarts.

Solution:

We have the Tx Rx pin taken our custom board. We were using jumpers to connect Azure to external device. Once we soldered the TX Rx, it worked

If I missed anything please let me know and I'd be happy to add it to my answer, or feel free to comment below with any additional information.

I hope this helps!

If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.
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1 person found this answer helpful.

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