correct way to connect/disconnect/reconnect on the LTE network of nrf9160

[James_Lee_K]

Hi, 

I have a question of correct way to connect/disconnect/reconnect from the LTE network to save power.

I already know about PSM mode.

But In south korea, SK telecom network doesn't support PSM mode.

So I want to save power by LTE modem power off and on.

And Target application working scenario is just one-time data sending each day and power-off.

So if I use function calls below, What is correct function calls of each step?

1. function calls that are used 

int lte_lc_init_and_connect(void)

int lte_lc_offline(void)

int lte_lc_power_off(void)

2. if do disconnect network and modem power-off

lte_lc_offline -> lte_lc_power_off

3. if do reconnect network

lte_lc_init_and_connect

if there are any cautions using function calls above or

if there are any good way to save power,  Please let me know.

[Heidi]

Hi!

int lte_lc_init_and_connect will turn on the modem (or switch it into "Normal" mode by sending AT+CFUN=1 and attempt a connection).

int lte_lc_offline sends AT+CFUN=4 to put the modem into "Offline" or "Flight Mode". int lte_lc_power_off sends AT+CFUN=0 to put the modem into "Power Off" mode. 

The main difference between "Offline" mode and "Power Off" mode is that AT+CFUN=0 triggers a file sync to save the present configurations to flash. The flash limit for write cycles is 10 000, so to put that into perspective, doing a file sync three times a day means this limit will not be hit for approximately ten years. 

Power consumption wise, they both have a base current of 4uA. 

Since you are only going to be sending this command once a day, exceeding the flash limit for write cycles isn't really a concern, so I recommend putting the modem in "Power Off" mode.

 

Let me know if you need more information!

Best regards,

Heidi

[James_Lee_K]

Hi, heidi,

Thank you for your reply.

After i try and if there  is any question, I will ask again.