W32K hang, unable to reset

We have a SL6087 with firmware R7.46 without any OpenAT application running.
In this particular application we set AT+W32K=1 and control the sleep mode with DTR signal.

To reduce communication we monitor the module by looking at the FLASH_LED signal.

Occasionally the module seems to “hang” somehow, and it’s not possible to power off normally (with the AT+CPOF sequence) as the module no longer responds to any AT commands.
When that happens, it’s also not possible to even RESET the module using the documented reset procedure.
The only thing that seems to help is to remove power completely, or reduce power below usable levels.

This hang can happen after hours, or after several days of operation, making it very difficult to test things.

Power draw from the module when it enters this hang is a solid 84mA @ 3.8V.

I haven’t seen anything in documentation that the emergency reset is inoperable when something happens to the module in W32K mode.

Has anyone else run into this problem? Does anyone know if upgrading the module firmware helps?

Hi tobias,

I beleive there is some application running whch is giving this command. :question:
Never ran into such kinda problem. May be if u tell some steps or something which i could try to simulate your use case and see whether the problem is there or not…

Upgrading might help you. It’s kinda big upgrade from 7.46 to 7.52. Not sure, but most of the bugs would have been fixed…

still, lemme know if i could do some tests at my end with 7.46


It’s been a while but I thought I’d update a little.

The module is controller by an external microcontroller in this case.

I tried to update one to 7.52 and after two weeks of the problem not appearing I thought it was safe to say it was resolved, but on the third week it happened again.

The reset procedures do not work and the only way to resume operation when it happens is to drop power to the module to below 3V.

The reset procedures work fine until the problem occurs.

Presumably the problem is triggered by network problems, but more than that I haven’t been able to determine.