Mbed-os: mbed Cellular APIs and 3GPP PSM

[wajahat-ublox]

Description

There is a method opt_power_save_mode in AT_CellularPower class. It is responsible for controlling the 3GPP Power Saving Mode. I want to know how function call for this method is to be made? To my understanding, the AT_xxxxx classes are not exposed directly to user application and EasyConnect + ConnectionFSM are using methods from AT_xxxxxx classes but currently AT_CellularPower::opt_power_save_mode is not used by ConnectionFSM. Can someone explain a little?

Issue request type

[X] Question
[ ] Enhancement
[ ] Bug

[mirelachirica]

I suggest adding it in FSM.
Either:
void CellularConnectionFSM::state_init() { _power->opt_power_save_mode(); nsapi_error_t err = _power->is_device_ready()

or in init() after _power is available:

nsapi_error_t CellularConnectionFSM::init() { _power = _cellularDevice->open_power(_serial); if (!_power) { stop(); return NSAPI_ERROR_NO_MEMORY; } _power->opt_power_save_mode(...)

[wajahat-ublox]

Thanks for the answer but it is unclear to me as how this allows the user to control the power saving mode? Looks like it will always be enabled if i call the method from CellularConnectionFSM::state_init() or CellularConnectionFSM::init()

[mirelachirica]

I see. It would be needed to be used independently in the application at any time, right?

[wajahat-ublox]

I suppose so because not all user applications would want to enable the power saving mode.

[philwareublox]

Some applications might want to change the power saving mode from time to time.

[mirelachirica]

EasyCellularConnection doesn't provide direct access to opt_power_save_mode(), at the moment. It needs to be enhanced to support this alone or support a mechanism to give direct access to power interface to the application. Would you need a proposal patch for the first solution?

[wajahat-ublox]

What would be the difference between first and second solution as both will allow user application to control the PSM, is that correct?

[mirelachirica]

Yes, no difference from user's perspective.

[wajahat-ublox]

Since this commit, the _power object is deleted as soon as the device is ready so i am not sure how either of the solutions can work.

[mirelachirica]

You are right, that is the next problem. I will have to discuss this issue with the team after the holiday ~2 weeks, plan and come up with a full solution to this problem.

[wajahat-ublox]

A friendly reminder.

[mirelachirica]

One approach is getting access to cellular device and serial from EasyCellularConnection: PR https://github.com/ARMmbed/mbed-os/pull/7795 and through device, access to power/open_power().

EasyCellularConnection *ecc = reinterpret_cast<EasyCellularConnection*>(iface);
CellularPower *power = ecc->get_device()->open_power(ecc->get_serial());
power->opt_power_save_mode(0, 0);

What do you think?

[wajahat-ublox]

Looks like it does solve the problem. Thank you