WP7605 is, after the IDLE state continued for several hours, Wakeup by SMS does not work properly

I am designing a GPS tracking device using WP7605.
The device transitions to IDLE immediately after powering on.
The application simply detects SMS arrival and sends GPS information to the server.
And it changes to an IDLE state again.

If WP7605 receives SMS at 3 minute intervals, it will not respond to SMS after 1-6 hours. At this time, RRC State did not change from Connected.

Recovery method:
-Connect to PC with USB cable
-Detach and Attach

Apparently after Paging, the radio stayed there.
This problem will occur 100%. FW R13.3 (Softbank — GCF)
Please help solve this problem.

Hi akatagiri1977,

Are you developing Legato app or you are using external processor?


Thank you for the your reaction.
The device currently under development uses only the WP7605 processor.
Therefore, only Legato APP is working.

If I understand correctly, your app works after boot up, but it enter suspend then no longer work?
Is it possible to try different carrier SIM card?

And during this state:

If WP7605 receives SMS at 3 minute intervals, it will not respond to SMS after 1-6 hours. At this time, RRC State did not change from Connected.

Would you please check and share below?



Thank you for the reaction.

This product works only with WP7605 processor.
In other words, only Legato APP and no external MPU is used.

Battery – DC IN — WP7605 ----LTE/GPS Antenna

The operation cycle is as follows:

-Power ON
-Auto LTE Attach
-MS-Based A-GPS Start
-Send Positioning Data to Cloud
-APP end
-The module automatically switches from Aciteve to Idle (Suspend mode).
SMS arrives (3-minute cycle) (*)

  • Module resumed from Idle (Suspend mode)
    –Auto LTE Attach
    -MS-Based A-GPS Start
    -Send Positioning Data to Cloud
    -APP end
    Repeat waiting for SMS arrival.(goto *)

It takes a lot of time to reproduce this problem, so it is difficult to try with other carrier SIMs.

The following AT command results are currently saved.
Current Time: 54733 Temperature: 23
Modem Mitigate Level: 0 ModemProc Mitigate Level: 0
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
IMS reg state: UNKNOWN IMS mode: Not Support
LTE band: B3 LTE bw: 15 MHz
LTE Rx chan: 1674 LTE Tx chan: 19674
EMM state: Registered Normal Service
RRC state: RRC Connected

PCC RxM RSSI: -72 RSRP (dBm): -94
PCC RxD RSSI: -71 RSRP (dBm): -92
Tx Power: 0 TAC: 1857 (6231)
RSRQ (dB): -8 Cell ID: 00347102 (3436802)


The !GSTATUS response looks ok, unit still registered so it should able to receive SMS, but info not enough to tell what happens.

Can you try resume WP (connect USB to PC), then capture Legato log for both incoming SMS and outgoing SMS?

Please also try “cm” tool to send/receive SMS.

And does your app set wake lock during incoming SMS?

Thank you for your reply.
When this happens, when I connect the USB cable to the WP7605, sometimes it starts working properly and sometimes it doesn’t.
If it doesn’t work after connecting USB, try sending / receiving SMS and getting DM logs.

Please tell me one.
The application works as follows:
However, it does not have a wakeup source.
1.Idle (Suspend mode)
2.SMS arrival
3.A-GPS MS-Based positioning start 5 seconds
4. Send GPS positioning result to server
5. Continue GPS positioning for 1 minute
6. Send GPS positioning result to server
7. It will automatically switch to Suspend,
(Sometimes at this time, RRC Connected stays and SMS
Is in a state where it cannot be received. )

Can this issue occur if the application does not hold Wakeup resources from 1 to 7?

Hi akatagiri1977,
Personally, I would hold wake lock at step 2 during incoming SMS callback to make sure system stay awake for the remaining actions, then release the wake lock at step 7.

If we don’t hold the wake lock, system may enter suspend mode quickly thus the remaining action freeze and not guarantee.

Anyhow, further test and Legato log may show more hints.
Hope it helps.

Thank you very much for your advice.
Anyway, I hope to add Wake Lock and get good results.
I’ll let you know about additional results.

BR Katagiri