AT_CLIENT app not working

[David Zapata]

Hello,

I have a Thingy91 pca20035 board (not the DK). So far, I have had success building my own modifications of the asset_tracker application by building it using SES and loading the HEX file into the device by using the nRF connect programmer. 

My issue is that I am not able to make the AT_CLIENT work. I tried programming the device with the default HEX file (both the image_dfu and the image_full version) found in https://www.nordicsemi.com/Software-and-Tools/Prototyping-platforms/Nordic-Thingy-91/Download#infotabs (the asset_tracker application found there works just fine). I have tried both COM ports in the nRF connect LTE link monitor. I have also the "auto device/port filter" option unchecked. I have tried turning on and off the device as well as reloading the LTE Link Monitor several times. All I see is this:

Additionally, the UART, Modem, UICC and LTE indicators are red color, while the PDN indicator is grey in the LTE Link Monitor.

It would be nice if you guys have any suggestion?

[Heidi]

Hi!

Since you mention trying both image_full and image_dfu_hex, how are you actually flashing the application to your device? Are you flashing over USB using MCUBoot, or using a debugger (like the nRF960 DK)? 

Best regards,

Heidi

[David Zapata]

Hi Heidi,

As I wrote in my question, I am loading the HEX image into the device using the nRF connect "programmer". I guess "programmer" uses MCUBoot deep inside, but I really don't know. 

 

After writing my question, I kept plugging and unplugging the device, resetting the LTE Link Monitor and turning on and off the device (since that was one suggestion for one similar question) and it worked just once! HOWEVER, I was not able to make it work again. So I suspect something funky is happening. I tested with another USB cable, but I saw no difference. 

[Heidi]

Hi, so you're not using a debugger but just trying the load the hex file onto the PCA20035 board directly with USB? Did you follow these steps?

If you want to use MCUboot, please see this tutorial on how to do that.

[David Zapata]

Yes, I followed those steps for loading the HEX image into the Thingy91 PCA20035. It has worked so far several times for me.

I am sure the AT_CLIENT image is correctly loaded into the device since after trying to connect to LTE Link Monitor a few more times (using the same HEX image), it connected once (but only once). I was not able to make a successful connection again. Is that a known issue? Could it be that the device is waiting for something before being able to respond to AT commands?

[Heidi]

No, this isn't a known issue. There could be something wrong with your device.

Could you send over the log file from LTE Link Monitor? Or is it completely empty? 

What AT Commands are you trying to send to the modem?