# No URCs or Network Recovery After Wake-Up From Hibernate (CEREG:4 Stuck) **URL:** \ **Category:** Uncategorized\ **Created:** [May 30, 2025, 2:26pm UTC](https://forum.sierrawireless.com/t/no-urcs-or-network-recovery-after-wake-up-from-hibernate-cereg-4-stuck/35004 "2025-05-30T14:26:43Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![zsen](https://avatars.discourse-cdn.com/v4/letter/z/b487fb/32.png) [@zsen](https://forum.sierrawireless.com/u/zsen)\ **Post date:** [May 30, 2025, 2:26pm UTC](https://forum.sierrawireless.com/t/no-urcs-or-network-recovery-after-wake-up-from-hibernate-cereg-4-stuck/35004/1 "2025-05-30T14:26:43Z")
Modem fw: HL7812.5.5.17.0-24.03.0.FreeRTOS.w10 We’ve made some progress on this issue [Unexpected GPIO6 and fast shotdown pin Behavior When Trying to Enter PSM on HL7812 – Not Matching Docs](https://forum.sierrawireless.com/t/unexpected-gpio6-and-fast-shotdown-pin-behavior-when-trying-to-enter-psm-on-hl7812-not-matching-docs/34986). After setting `AT+KSIMDET=0`, the device is now able to enter sleep modes correctly, in my case, it successfully goes into **hibernate**. However, I’m now running into a new problem: the device **never wakes up** from hibernate after I assert the wake-up pin. It also doesn’t transition from `CEREG:4` (not registered) to `CEREG:5` (registered, home network), even after the wake-up signal. Wake-up Procedure I Followed: 1. Assert the wake-up pin (set it high). 2. Wait for a `+KCELLMEAS` URC (or any sign of life from the modem). But nothing happens — I don’t receive any URCs, and the modem stays stuck in `CEREG:4`. Should I open a new issue to track this wake-up behavior, or is it okay to continue the discussion here? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [May 30, 2025, 2:34pm UTC](https://forum.sierrawireless.com/t/no-urcs-or-network-recovery-after-wake-up-from-hibernate-cereg-4-stuck/35004/2 "2025-05-30T14:34:26Z")
Can you enter AT command after asserting wake up pin? Btw, you can have a look on this application note > **[HL78xx - Low Power Modes Application Note](https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/hl78xx_low_power_modes_application_note/)** > > This document provides a detailed description of the HL78xx’s low power modes while it is configured in PSM or eDRX. BTW, does this issue relate to this thread? > [@Unexpected +KCELLMEAS URC prevents PSM from functioning properly](https://forum.sierrawireless.com/t/unexpected-kcellmeas-urc-prevents-psm-from-functioning-properly/33815/7): > > Yes, here is a log that shows psm works good without KCELLMEAS=1,10. I think the problem may not be the KCELLMEAS here, As you said here, something is waking up the module, and automatically I am getting kcellmeas after 10secs as it is expected according to the reference guides. I think the psm loop issue occurs because of my software, that doesn’t expect that much quick kcellmeas. The problem is that the first wake up by something we dont know ATM. +CEREG: 4,,,,,,"00001111","00001111" 3957… ---
**Author:** ![zsen](https://avatars.discourse-cdn.com/v4/letter/z/b487fb/32.png) [@zsen](https://forum.sierrawireless.com/u/zsen)\ **Post date:** [June 2, 2025, 4:02pm UTC](https://forum.sierrawireless.com/t/no-urcs-or-network-recovery-after-wake-up-from-hibernate-cereg-4-stuck/35004/3 "2025-06-02T16:02:25Z")
It looks like the issue was caused by using `AT+KCELLMEAS=0`. Based on the command description, I assumed that mode 0, which provides standard cell coverage details, would result in the fastest URC response. Maybe I misunderstood how it works? In any case, switching to `AT+KCELLMEAS=1,35` solved the problem for me. > [@jyijyi](#): > > Can you enter AT command after asserting wake up pin? Yes, there is no problem with running an at cmd. > [@jyijyi](#): > > Btw, you can have a look on this application note > > [https://source.sierrawireless.com/resources/airprime/application\_notes\_and\_code\_samples/hl78xx\_low\_power\_modes\_application\_note/](https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/hl78xx_low_power_modes_application_note/) This is what I am following to set power configs. > [@jyijyi](#): > > BTW, does this issue relate to this thread? No, not with this thread; I think it was more relevant to the [PSM issue](https://forum.sierrawireless.com/t/unexpected-gpio6-and-fast-shotdown-pin-behavior-when-trying-to-enter-psm-on-hl7812-not-matching-docs/34986/12) thread than this one. btw, I checked the issue, and the modem sw version at that time was 5.5.8. it looks like that psm issue has existed since that version.