LPUART req pin low when expected high

[Roman Veselskyi]

Hello team,

I am trying to test the lpuart functionality on our custom PCB and it doesn't work, but the issue is that by some reason even original samples from the SDK doesn't work. 

I just take the sample Bluetooth: HCI low power UART - build it with no changes for the nrf52840 and flash to nRF9160DK nRF52840. 

Then I take the Cellular: LTE Sensor Gateway - build it with no changes for the nrf9160/ns and flash into nRF9160DK to nRF9160. 

And I get these errors:

[00:00:00.311,279] <wrn> lpuart: req pin low when expected high
[00:00:00.311,401] <err> lpuart: Empty receiver state:4

[00:00:01.053,436] <err> bt_gatt: Unable to import the key for AES CMAC -134

*** Booting nRF Connect SDK v3.1.1-e2a97fe2578a ***
*** Using Zephyr OS v4.1.99-ff8f0c579eeb ***
[00:00:00.309,295] <inf> lte_ble_gw: LTE Sensor Gateway sample started
[00:00:00.309,509] <inf> lte_ble_gw: Initializing Bluetooth..
[00:00:00.311,279] <wrn> lpuart: req pin low when expected high
[00:00:00.311,401] <err> lpuart: Empty receiver state:4
[00:00:00.562,255] <inf> lte_ble_gw: Establishing LTE link (this may take some time) ...
[00:00:01.035,552] <inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)
[00:00:01.035,583] <inf> bt_hci_core: HW Variant: nRF52x (0x0002)
[00:00:01.035,614] <inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 252.16862 Build 1121034987
[00:00:01.043,182] <inf> bt_hci_core: HCI transport: H:4
[00:00:01.043,273] <inf> bt_hci_core: Identity: C3:2F:71:87:B9:99 (random)
[00:00:01.043,304] <inf> bt_hci_core: HCI: version 6.1 (0x0f) revision 0x1069, manufacturer 0x0059
[00:00:01.043,334] <inf> bt_hci_core: LMP: version 6.1 (0x0f) subver 0x1069
[00:00:01.043,365] <inf> lte_ble_gw: Bluetooth ready
[00:00:01.048,919] <inf> lte_ble_gw: Scanning...
[00:00:01.053,436] <err> bt_gatt: Unable to import the key for AES CMAC -134
+CEREG: 2,"A88E","0901B92B",9
+CSCON: 1
+CEREG: 1,"A88E","0901B92B",9,,,"00000001","00100001"
[00:01:25.829,620] <inf> nrf_cloud_info: Device ID: nrf-350457790695371
[00:01:25.830,169] <inf> nrf_cloud_info: IMEI:      350457790695371
[00:01:25.830,596] <inf> nrf_cloud_info: Modem FW:  mfw_nrf9160_1.3.7
[00:01:25.830,627] <inf> nrf_cloud_info: Protocol:          MQTT
[00:01:25.830,657] <inf> nrf_cloud_info: Download protocol: HTTPS
[00:01:25.830,688] <inf> nrf_cloud_info: Sec tag:           16842753
[00:01:25.830,718] <inf> nrf_cloud_info: Host name:         mqtt.nrfcloud.com

The build configuration is attached:

SDK 3.1.1

[Hung Bui]

Hi Roman, 
What you reported could be not related to LPUART. Can you take a look here? 

bt_gatt: Unable to import the key for AES CMAC -141
Amanda provided a link to the fix. 

[Roman Veselskyi]

Hi,

Thanks for the reply, but what about first two errors? 

[00:00:00.311,279] <wrn> lpuart: req pin low when expected high
[00:00:00.311,401] <err> lpuart: Empty receiver state:4

[Hung Bui]

Hi Roman, 
My suggestion is to try testing with only one side first. You can manually pull the LP pin low and high to test. Have you tested with the lpuart sample ? 
Please double check if the req and rdy pins are configured correctly. 

[Roman Veselskyi]

Hello Hung Bui ,

I am using the nRF9160DK together with the samples from SDK with no changes, this info was mentioned on request. I am expecting the configuration must be correct at least from the Nordic provided samples, did you try it on your side with DK?  

[Hung Bui]

Hi Roman, 
Sorry I thought that you didn't have the lpuart: Empty receiver state:4  error with the DK. 

I think it's a known issue: 
RE: Bluetooth HCI lpuart issue - nRF9160 + nRF52840

But do you have other error after the <err> lpuart: Empty receiver state:4 ? 
We need to see if you have the same problem or not.