nRF9160: LTE Sensor Gateway on Thingy:91

[Mattchew]

I am trying to fun the LTE Sensor Gateway on the Thingy:91.

The boards are missing from zephyr so I copied nrf52840_pca20035 and nrf9160_pca20035 from ncs\nrf\boards\arm.

When running samples/bluetooth/hci_uart.

The BLE and UART don't seem to be configured correctly. I get "warning: BT_CTLR_DTM_HCI" and "warning: BT_CTLR_ASSERT_HANDLER".

I created ncs\zephyr\samples\bluetooth\hci_uart\nrf52840_pca20035.overlay based on https://devzone.nordicsemi.com/f/nordic-q-a/51693/hci_uart-on-thingy-91

This still doesn't work.

Adding the lines below to nfr52840_pca20035\Kconfig.defconfig seem to fix the BLE issues? UART is not working so, I don't know if it is working.

config BT_CTLR
default BT

When running samples/nrf9160/lte_ble_gateway I get errors "warning: UART_2_NRF_UARTE" and "warning: UART_2_NRF_FLOW_CONTROL"

I see that nrf9160_pca20035ns.overlay is missing from the folder but I am not sure how to modify it. There is no status light configured. 

Help?

[Sigurd]

Hi,

The Thingy:91 is not configured for this use-case at this time. A colleague of mine tested this a couple of days ago, and here it the changes/files used:

thingy_91_lte_changes.zip

nrf_changes.diff applies to ncs/nrf

zephyr_changes.diff applies to ncs/zephyr

nrf52840_pca20035.conf and .overlay should be placed in ncs/zephyr/samples/bluetooth/hci_uart/

nrf9160_pca20035.overlay should be placed in ncs/nrf/samples/lte_ble_gateway/

Use Segger RTT viewer to view the log output. Note that you need to manually keep the nRF52 in reset for several seconds before releasing it. Holding it in reset is done by grounding TP8 (apply patch to enable reset pin). On the nRF91-DK we are using a GPIO line between the nRF52 and nRF91 in order to reset the nRF52. I believe it should be possible to add this functionality to the thingy:91 as well, by using one of the lines originally used by the UART, e.g. pin 20. But there are some bugs on the master branch at the moment, so this reset functionality is currently not working reliably.

[Mattchew]

I don't see the device show up on nRF Cloud. I also am not able to see anything on the RTT viewer. 

[Cody]

Okay I am trying it again this morning and I have had a little bit of luck, following your directions exactly I can get the Thingy91 to boot up and blink blue LEDS then blue and red LEDS.

This is with one caveat - I have to have the Thingy91 plugged in to my computer via USB. It appears that if I unplug the USB cable from the Thingy91 and attempt to reboot the device, it will fail.

[Sigurd]

Cody said:

This is with one caveat - I have to have the Thingy91 plugged in to my computer via USB. It appears that if I unplug the USB cable from the Thingy91 and attempt to reboot the device, it will fail.

You are correct. In the original usb_uart_bridge sample, the nRF52840 is just put into system OFF sleep mode when there is no USB connected. But in our use-case with the LTE gateway, we need the nRF52840 powered on for the BLE HCI.

Should be a simple fix for this, in hci_uart_with_usb_uart_bridge, modify the function power_thread() in main.c to look someting like this:

void power_thread(void)
{
	while (1) {
		if (!nrf_power_usbregstatus_vbusdet_get()) {
			//nrf_power_system_off
			k_sleep(100);
		}
		k_sleep(100);
	}
}

I have not tested this, but alternatively we could perhaps just remove the power thread functionality completely, if the nRF52840 is on all the time anyways.

I hope this helps. Let me know how it goes.

[Cody]

Thank you Sigurd, will attempt this as soon as I can.

UPDATE: After applying the power thread related patch above, things appear to be working well. Testing continues, will let you know if I encounter additional issues.

[Dheeraj]

Hi Sigurd,

We have tried the above fix and able to receive the BLE values from nRF52840_PCA20035.

But we encountered an issue.

1. Connected the Thingy91(PCA20035)  using USB and SWD cable via nRF9160 DK(PCA10090)

flashed the hci_uart_with_usb_uart_bridge (NOTE: Disabled the power_thread) on nRF52840_PCA20035 and flashed the application Image on nRF9160_PCA20035. 

Observed the BLE values and sending to the nRF cloud. --> NO ISSUE

Issue Scenario:

2. Now, we have removed thingy91 from USB and SWD cable (Kept thingy91 as standalone), still, BLE values observed and sent to the nRF cloud.

BUT,

3. We have tried resetting (Power cycle) the device using nrf9160 SW3 Button, in this particular case we have observed: "Scanning failed to start, err -12".  and NO BLE values observed from nRF52840.

Recovery: Connect the thingy91 back to the system with USB  and give the power cycle. Observe the BLE values. 

Expectation: The nRF52840 should send BLE values, though we removed the USB and power cycle the Thingy91 using SW3/SW4.  

If Thingy91 is NOT connected to USB, nRF52840 should get 1.8V power supply from PMIC (ADP536x), but it looks like this is not happening. Results we need to connected Thingy1 to USB in order to get the BLE values. 

Please help us in directing to the right way to fix the above issue. 

NOTE: We have tried to test on 2 Thingy91 devices, observed the same behavior. 

[Marshed]

This works fine with your hex file, however when i apply the patch and use segger embedded studio to make the hex file and upload the program runs with this error

Bluetooth init failed (err -19)

please assist