We are using the nRF5340 with the nRF7002 Wi-Fi module on our custom board. Our application periodically sends data to a server. During continuous testing, we encountered an issue while trying to bring up the Wi-Fi interface. Below are the details:
Issue Description:
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After completing Wi-Fi operations, we shut down the Wi-Fi module and put the system into IDLE mode.
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When exiting shutdown mode and attempting to reinitialize Wi-Fi, the following error occurs:
<err> wifi_nrf: nrf_wifi_fmac_chg_vif_state: RPU is unresponsive for 10 sec<err> wifi_nrf: nrf_wifi_if_start_zep: nrf_wifi_fmac_chg_vif_state failed<err> nrf7002_wifi: Cannot bring up iface (-1) -
We are following the shutdown and exit shutdown procedures as demonstrated in the sample shutdown code provided in the SDK.
Steps Taken:
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Power Supply Check:
- Based on recommendations from this DevZone thread, we verified that the VBAT supply to the Wi-Fi module is stable.
- The LDO used for VBAT can provide up to 500mA, meeting the suggested 300mA requirement.
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Continuous VBAT Supply:
- We provide a continuous supply to the nRF7002 VBAT line, even when the Wi-Fi module is in shutdown mode.
- We suspect this continuous supply could be contributing to the issue but need clarification on whether this is acceptable.
Questions:
- What could cause the RPU to become unresponsive during Wi-Fi initialization in this scenario?
- Is providing a continuous VBAT supply to the nRF7002 Wi-Fi module during shutdown mode recommended, or should it be disconnected?
- Are there additional guidelines or hardware considerations we should review to ensure proper behavior during shutdown and reinitialization?
- Is there any additional debugging or logging configuration that might help us isolate the root cause?