Thingy:91 Serial LTE modem PSM

RE: Thingy:91 Serial LTE modem PSM

SilasV — Sun, 24 Jan 2021 20:05:11 GMT

Hi Stian

Just for the test sake, I tried this in the prj file:

# Enable GPIO wakeup if sleep is expected
CONFIG_SLM_GPIO_WAKEUP=y
CONFIG_SLM_INTERFACE_PIN=26

Although my custom board does not use P0.26 pin, this pin is left open on the current version of the nrf9160 PCB. And surprisingly it works!!

when powered up, it does not respond with "ready", but just sending a random character, it responds with "ready", so I believe that after power up, the modem is in sleep mode. Sending character 'a' wakes it up, and then sending regular commands for UDP connection and sending data. After that sending "AT#XSLEEP=1" to put it sleep mode. I tried wake up after 15min, and it worked as expected.

Is there any time limit to which the sleep mode? I tried wake up after 50min, and it did not respond with 'ready'. In normal application, the sleep period of the device would be between 15min to 30min (user configurable). Would you please let me know if there is any limitation on the sleep period for nRF9160 .

Thanks you

RE: Thingy:91 Serial LTE modem PSM

Stian Røed Hafskjold — Wed, 20 Jan 2021 23:20:14 GMT

Hi, I just tried waking up using a dummy byte over UART, and I managed to do it successfully while also keeping the connection.

First you have to set CONFIG_SLM_INTERFACE_PIN to 19, which is the uart0 RX on the thingy91.

Then in the exit_idle() function add a 1 second delay before slm_at_host_init(), so that the dummy byte finishes transmitting before the at host init. The function should now look like this:

static void exit_idle(struct k_work *work)
{
	int err;

	LOG_INF("Exit Idle");
	gpio_pin_interrupt_configure(gpio_dev, CONFIG_SLM_INTERFACE_PIN,
				     GPIO_INT_DISABLE);
	gpio_remove_callback(gpio_dev, &gpio_cb);
	/* Do the same as nrf_gpio_cfg_default() */
	gpio_pin_configure(gpio_dev, CONFIG_SLM_INTERFACE_PIN, GPIO_INPUT);
	/* Restart SLM services */
	
	k_sleep(K_MSEC(1000)); // <- ADD THIS LINE
	
	err = slm_at_host_init();
	if (err) {
		LOG_ERR("Failed to init at_host: %d", err);
	}
}

Here are the AT commands I used in the LTE link Monitor:

a
Ready
AT+CFUN=1
OK
AT+CEREG=5
OK
AT+CPSMS=1,"","","10100001","00000000"
OK
AT+CEREG?
+CEREG: 5,5,"0AD3","020EC516",7,,,"00000000","00000110"
OK
AT#XSLEEP=0
a
Ready
Ready
AT+CEREG?
+CEREG: 5,5,"0AD3","020EC516",7,,,"00000000","00000110"
OK

So you can see that I'm waking up with just sending the letter "a", then I get the Ready response, and then you see from the AT+CEREG? that the modem is still connected

I also tried unplugging the USB after AT#XSLEEP=0, and plugging it back in, and it still works, still connected to the network (you have to reconnect to the USB device in the LTE Link Monitor software)

NOTE

I see that you are using AT#XSLEEP=1. This command is shutting down the modem, disconnecting from the network before going to sleep. Use AT#XSLEEP=0 if you want to keep the connection

RE: Thingy:91 Serial LTE modem PSM

SilasV — Wed, 20 Jan 2021 16:03:43 GMT

Thanks for your suggestion. On my custom board, I am using P0.05 - RX and P0.06 TX, and I configured the RX pin=5 as wakeup --> CONFIG_SLM_INTERFACE_PIN=5, but that did not help, the modem does not respond on power up (I don't receive Ready response).

So I am considering a dedicated pin for the wakeup. I will soon get the new version of PCB.

Thank you

RE: Thingy:91 Serial LTE modem PSM

Michal Mühlpachr — Sun, 17 Jan 2021 00:12:30 GMT

Hi, thank you for hints.

I have CONFIG_SLM_GPIO_WAKEUP=y and CONFIG_SLM_INTERFACE_PIN=26 in prj.conf.

In thingy91_nrf9160ns.overlay I have:

&uart1 {
status = "disabled";
};

&uart0 {
/delete-property/ hw-flow-control;
/delete-property/ rts-pin;
/delete-property/ cts-pin;
};

I am able to wake up nRF9160 by GPIO.

I am getting sometimes during nRF9160 wake up and always after closing serial port in nRF Connect LTE LInk Monitor those logs in nRF9160 RTT:

[00:00:07.882,720] <wrn> at_host: RX_STOPPED (4)
[00:00:07.882,720] <wrn> at_host: RX_STOPPED (8)
[00:00:07.882,812] <wrn> at_host: RX_STOPPED (4)
[00:00:07.882,843] <wrn> at_host: RX_STOPPED (8)
[00:00:07.882,904] <wrn> at_host: RX_STOPPED (4)
[00:00:07.882,934] <wrn> at_host: RX_STOPPED (8)
[00:00:07.882,995] <wrn> at_host: RX_STOPPED (4)
[00:00:07.883,026] <wrn> at_host: RX_STOPPED (8)
[00:00:07.883,087] <wrn> at_host: RX_STOPPED (4)
[00:00:07.883,117] <wrn> at_host: RX_STOPPED (8)
[00:00:07.883,178] <wrn> at_host: RX_STOPPED (4)
[00:00:07.883,209] <wrn> at_host: RX_STOPPED (8)

After that nRF9160 stops to communicate on serial port (do not react on AT). Serial port is reopened.

In this state I have to power cycle nRF9160.
How to fix that please ?

I am using AT+CPSMS=1,,,"00100001","00000000" for PSM.

After AT#XSLEEP=1 while in +CEREG: 5 and wakeup by GPIO (button on Thingy91) nRF9160 always re-register into EPC open new session and goes through +CEREG: 2.
How to keep session during PSM please and save power for re-register please ?

RE: Thingy:91 Serial LTE modem PSM

Stian Røed Hafskjold — Tue, 12 Jan 2021 22:00:42 GMT

I believe you can try to set the UART RX pin as the wakeup pin. Then send a dummy byte from the UART host to wake up the nRF9160. The level changes on the UART RX pin should be equivalent to pushing a button. I've not been able to test this my self, but I don't see why it shouldn't work. It's worth a try.

RE: Thingy:91 Serial LTE modem PSM

SilasV — Fri, 08 Jan 2021 00:16:05 GMT

Hi, thanks for your reply :)

For my current version of custom board, I do not have a GPIO pin designed to get wakeup trigger from external MCU.

Is there a way to config nRF9160 to just wake up from the UART1 after putting nRF9160 to sleep with the SLEEP command?

In my next version of the pcb design, I will make sure to update and include this GPIO wakeup from external MCU.

Thank you!

RE: Thingy:91 Serial LTE modem PSM

Stian Røed Hafskjold — Thu, 07 Jan 2021 14:56:49 GMT

Hi, I tried this on a thingy91 and it works almost out of the box, with a couple of changes. I tried with the Serial LTE Modem application from NCS 1.4.0.

You have to add CONFIG_SLM_GPIO_WAKEUP=y and CONFIG_SLM_INTERFACE_PIN=26 to the prj.conf as you did. No other changes are necessary to wake up using the button.

Here is my full prj.conf:

#
# Copyright (c) 2019 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: LicenseRef-BSD-5-Clause-Nordic
#
# General config
CONFIG_LOG=y
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_STACK_SENTINEL=y
CONFIG_NEWLIB_LIBC=y
CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y
CONFIG_RING_BUFFER=y

# Segger RTT
CONFIG_USE_SEGGER_RTT=y
CONFIG_RTT_CONSOLE=y
CONFIG_UART_CONSOLE=n
CONFIG_LOG_BACKEND_RTT=y
CONFIG_LOG_BACKEND_UART=n

# Network
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_NATIVE=n

# BSD library
CONFIG_BSD_LIBRARY=y
# Align the max FD entry to BSD_MAX_SOCKET_COUNT(8)
CONFIG_POSIX_MAX_FDS=8
# Enable below for modem trace
#CONFIG_BSD_LIBRARY_TRACE_ENABLED=y

# Use GPIO
CONFIG_GPIO=y
CONFIG_GPIO_NRFX=y
CONFIG_GPIO_NRF_P0=y

# UART interface
CONFIG_SERIAL=y
CONFIG_UART_ASYNC_API=y
CONFIG_NRFX_TIMER2=y

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

# Stacks and heaps
CONFIG_MAIN_STACK_SIZE=4096
CONFIG_HEAP_MEM_POOL_SIZE=16384
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=8192

# AT_CMD
# Enable AT_CMD debug for details
#CONFIG_AT_CMD_LOG_LEVEL_DBG=y

# Device power management
CONFIG_DEVICE_POWER_MANAGEMENT=y

# Enable SUPL client support
#CONFIG_SUPL_CLIENT_LIB=y

# FOTA
CONFIG_HTTP_PARSER_URL=y
CONFIG_FOTA_DOWNLOAD=y
CONFIG_FOTA_DOWNLOAD_PROGRESS_EVT=y
CONFIG_DFU_TARGET=y
CONFIG_DOWNLOAD_CLIENT=y
CONFIG_DOWNLOAD_CLIENT_STACK_SIZE=4096
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_IMG_MANAGER=y
CONFIG_FLASH=y
CONFIG_IMG_ERASE_PROGRESSIVELY=y

# Application-specific
CONFIG_SLM_LOG_LEVEL_INF=y
# Enable GPIO wakeup if sleep is expected
CONFIG_SLM_GPIO_WAKEUP=y
CONFIG_SLM_INTERFACE_PIN=26
# Use UART_0 (when working with PC terminal)
CONFIG_UART_0_NRF_HW_ASYNC_TIMER=2
# Use UART_2 (when working with external MCU)
#CONFIG_SLM_CONNECT_UART_2=y
#CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2
# Use optional TCP/TLS Proxy
#CONFIG_SLM_TCP_PROXY=y
# Use optional UDP/DTLS Proxy
#CONFIG_SLM_UDP_PROXY=y

In order to reduce the idle current UART1 has to be disabled, since this is turned on by default in Zephyr. The easiest way to do this is to add an overlay file:

Add the following to a file called thingy91_nrf9160ns.overlay (or thingy91_nrf9160.overlay if you are not building for non-secure) and save the file in the project root folder:

&uart1 {
    status = "disabled";
};

You might have to delete the build folder for the new file to be found.

Then, build for board thingy91_nrf9160ns (or thingy91_nrf9160), and flash the FW.

Remember that the connectivity FW has to be flashed on the nRF52 in order to see the UART output over the USB connection.

Push the button and you should see the terminal print "ready".

RE: Thingy:91 Serial LTE modem PSM

SilasV — Thu, 24 Dec 2020 17:06:17 GMT

I have similar issue, (posted here)

After sending either AT#XSLEEP=0 or AT#XSLEEP=1, cannot wake up nRF9160 by sending any AT command.

The currents in both sleep or idle mode is lower than 10uA. I cannot measure the exact current, I am getting the Nordic Power Profiler soon which would help me measure currents for series of AT commands.

Really interested in wake up over serial comm, since I plan to use the nRF9160 just as SLM with external MCU.

requesting your help

RE: Thingy:91 Serial LTE modem PSM

helsing — Tue, 15 Dec 2020 14:55:50 GMT

Hi Michael,

I am seeing the same as you are. The device stops responding after AT#XSLEEP=0. I have not yet measured the current.

I will be investigate a few things tomorrow.

Best regards,

Håkon

RE: Thingy:91 Serial LTE modem PSM

Michal Mühlpachr — Sun, 13 Dec 2020 01:07:11 GMT

Are you able to wake-up nRF9160 after AT#XSLEEP=0 or AT#XSLEEP=1 please ?

RE: Thingy:91 Serial LTE modem PSM

helsing — Thu, 10 Dec 2020 10:17:00 GMT

Thank you for the clarification, I will measure the same way.

RE: Thingy:91 Serial LTE modem PSM

Michal Mühlpachr — Tue, 08 Dec 2020 00:41:02 GMT

Hi,

current and voltage is measured by https://www.joulescope.com/ on P1, I am interested in nRF9160 current consumption only. We are considering use for www.hardwario.com/.../

RE: Thingy:91 Serial LTE modem PSM

helsing — Mon, 07 Dec 2020 20:27:13 GMT

Hi Michal,

I will build this myself tomorrow. By the way, how do you measure the current? Do are you interested i the current for the whole board, or the nRF9160 only?

RE: Thingy:91 Serial LTE modem PSM

Michal Mühlpachr — Mon, 07 Dec 2020 11:24:38 GMT

typo: After AT#XSLEEP=0 or AT#XSLEEP=1 ...