MD4 real time clock and internal temperature sensor issue

David Dufour 7 years ago in Master modules / MD4 updated by mehdi tech87 3 years ago 8


I have several issue comes from a customer who run MD4/MC31 multimaster system.

They have MD4 who are not anymore able to keep the RTC.

To be sure, I took a kit apart and tested it myself. Finally, I move the MD4 alone and tried it with a very small program. Only value to show date/time/temp.

When it boot, the RTC is resetted and the temperature is OK (around 40 Celsius).

But when I update the date/time from iQanRun, the date and time appear to be OK, but the internal temp goes to -1C and give critical error.

I did a short video to show what I did and to show what's append.



There is some picture to complete:

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Under review

Thank you for the very detailed description of the issue.

I do no know what could cause this symptom, but my recommendation is to send the IQAN-MD4 for investigation/repair. 

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Hi Gustav,

Who is the best person to send unit(s) attention?

I'll send them to the canada division.

My customer have several unit like this.

Theses units are used on an electric school buses, in case this can help to figure out the problem.



I checked with my colleges in Canada and in the US, and they will contact you about this unit (if they have not done so already, I am a few days late)

Perfect, Aurelio already send me a RMA to return the two units I have in hand. If not already at the division, they are about to be.




I will be interested if you find a solution.  We have had many problems with the RTC failing on MD4s as well usually after about 12 months of operation.  We have had 5 units fail out of about 40 in the field so far.

we also have stopped using the RTC's in our applications as there were too many complaints.


Thank you all for reporting this problem, we also saw MD4 returns via the regular after-sales channels. 

In the investigation that followed, we found out that the failure of the RTC and the internal temperature measurement relate to a damaged RTC component, when the RTC failed it also affected the communication with the temperature sensor. 

A solution was implemented in MD4 production in September, the solution is giving better protection of the RTC component, making it less prone to failure.