NXQ1TXH5 wrong LED behavior when new charge after charge complete

[cbarbier]

Good morning,

We have a custom design with a wireless transmitter and receiver using NXQ1TXH5 chip. Our design is mature and functioning properly now. However we observe sometimes a corner case with the LED behavior when new charge occurs after a charge complete. Let me describe more how to reproduce this:

We put the receiver device on the transmitter. Charging starts properly and transmitter LED is blinking green. When device is fully charged, charge complete signal is sent, charging stops and transmitter LED is permanent green. All good. Then device is kept on transmitter and after a while, when device battery has discharged enough that device needs to be charged again, charge request is sent and transmitter starts charging again the device. Everything works fine except that transmitter LED keeps permanent green while we would expect it to be blinking green.

Have you ever seen this behavior?
We use LED configuration mode 11.

We also have NXQ1TH5DB1355 plugin board and we tried to get log while this behavior occurs but we did not find anything strange yet. When new charge is asked after charge complete we properly see again, signal strength packet, identification packet, configuration packet and then the duo control error/received power packets while new charge is occurring.

Best regards,

Corentin

[TomasVaverka]

Good morning Corentin,

I would like just to inform you that I have forwarded your question to our application engineer who supported the NXQ1TXH5 when it was an Active device. I hope he can still help.

BRs, Tomas

[TomasVaverka]

Good afternoon Corentin,

Please see below the answer I have just received from the application engineer.

I have no experience with this issue, but when I read the line:

"Everything works fine except that transmitter LED keeps permanent green while we would expect it to be blinking green."

...then I would expect this is something to be in the state diagram.

However, this project has stopped years ago and the designers are not there any more so I do not see a possibility to further investigate this. I'm sorry for that.

Please accept our apologies for not being to help more.

BRs, Tomas 

[TomasVaverka]

Good afternoon Corentin,

Please find the NXQ1TXH5 datasheet attached.
In paragraph 8.1.6 there is some explanation about the charged state. I hope it helps.

BRs, Tomas

[cbarbier]

Dear Tomas,

Thank you for your answers. Yes I read that part before in the datasheet but our wireless receiver is not sending these specific end of charge messages anyway.
However I think I could catch a difference when the issue happens compared to when it doesn't happen. In the log from the NXQ1TH5DB1355 plugin board:

- in normal behavior when LED restarts blinking green when charge restarts after battery level went too low, we can see in the wireless communication between transmitter and receiver that transition from "state charged" to "state dping" to identification and configuration and then to "state transfer":

- when issue occurs and LED keeps permanent green when charge restarts after battery level went too low, we can see in the wireless communication between transmitter and receiver that "state dping" and "state transfer" are missing :

Best regards,

Corentin