how to set mode of Serial LTE Modem

[jonas.woerner]

Im currently using a nRF9160 with SLM application as a modem on a nRF52840.

How can I configure the modem for NB-IOT or LTE by using the nrf52840?

My project is working, I just need a way to set it to NB-IOT only for example.

I found CONFIG_LTE_NETWORK_MODE, but this gives some errors.

kind regards,

Jonas

[Charlie]

Hi Jonas,

The following commands should work if you only want to use NB-IoT network.

AT+CFUN=4
AT%XSYSTEMMODE=0,1,0,0
AT%XSYSTEMMODE?

See https://docs.nordicsemi.com/bundle/ref_at_commands/page/REF/at_commands/mob_termination_ctrl_status/xsystemmode_set.html

Best regards,

Charlie

[jonas.woerner]

thanks, but is there any way of doing this by application? I want my app to configure the modem on start, so I dont have to change this manually.. The uart is already used by the modem driver I guess.. but does the driver have any way of letting me set this?

[Charlie]

Hi Jonas,

Sorry for misunderstanding. Do you mean by which application? I thought your nRF52840 as modem controlling chip already run applications like following, so you can send the commands from nRF52840 to nRF9160 through UART.

Cellular: SLM Shell (nordicsemi.com)

nRF91 Series as a Zephyr-compatible modem (nordicsemi.com)(Using Zephyr Cellular modem sample)

If the application means nRF9160 SLM, you can add an overlay-linkcontrol.conf with following configurations:

CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_NETWORK_MODE_NBIOT=y

Then add lte_lc_connect function after nrf_modem_lib_init.

	const int ret = nrf_modem_lib_init();

	if (ret) {
		LOG_ERR("Modem library init failed, err: %d", ret);
		if (ret != -EAGAIN && ret != -EIO) {
			return ret;
		} else if (ret == -EIO) {
			LOG_ERR("Please program full modem firmware with the bootloader or "
				"external tools");
		}
	}

        lte_lc_connect();

The SLM will connect with NB-IoT network automatically after reboot. The connection may take some time according to my test:

Ready
> AT%XSYSTEMMODE?

%XSYSTEMMODE: 0,1,0,0

OK
> AT+CFUN?

+CFUN: 1

OK
> AT+CEREG?

+CEREG: 5,1,"A8B3","03238D6E",9,,,"11100000","11100000"

OK

+CSCON: 0

+CEREG: 1,"A8B3","03238D69",9,,,"11100000","11100000"

Best regards,

Charlie