Backup mode with PMTK during VCC powered

I read in L96 Hardware Design about entering into backup mode:

There are two ways to enter into backup mode and back to full on mode.

  • Send “$PMTK225,4*2F” Command (the signal marked red line opens the switch in Figure 3) to enter
    into backup mode. The only way to wake up the module is pulling the FORCE_ON pin high (the
    signal marked red line closes the switch in Figure 3).
  • Cutting off VCC and keeping V_BCKP powered will make the module enter into backup mode from
    full on mode. As long as the VCC pin is powered, the module will enter into full on mode immediately.

What happend if L96 is entering on backup mode by PMTK-command during VCC is staing powered?

L96 will entered into backup mode and then enter into full on mode immediately?
L96 will remain in backup mode until a FORCE_ON signal is received?

Maybe other variants? (not entering backup mode at all, for example)
Please, clear me up.

Hi Ildar Belkin,

If you send a Perpetual Backup Mode command ($PMTK225,4*2F), the module will keep sleeping until FORCE_ON is pulled up. If you send a Periodic Backup Mode command, the module will wake up and sleep on time.

After sending a $PMTK225,4*2F command, VCC on or off has no effect on the function. And consumption of the two methods only have a few uA difference. But we suggest to turn off/on VCC only if you want to enter/exit Perpetual Backup Mode. This method is the most simple way to control.

Best regards.

Does it mean that sequence VCC connecting power → Sending $PMTK225,4*2F → VCC disconnecting power- VCC connecting power will stay the module in Perpetual Backup Mode after powering VCC??

Yes. The correct sequence for this method:

VCC connecting → Sending $PMTK225,4*2F → VCC disconnecting power → Recover VCC → Pulling up FORCE_ON >50ms → Wake up

Is it true if V_BCKP directly connecting to VCC and both controlled by one external switch simultaneously:

VCC and V_BCKP connecting → Sending $PMTK225,4*2F → VCC and V_BCKP disconnecting power → Recover VCC and V_BCKP → Pulling up FORCE_ON >50ms → Wake up

Does the module save last mode before VCC and V_BCKP off and recover it after VCC or / and V_BCKP power on?

Hi Ildar Belkin,

A completely power off will clear up the settings which store in RAM memory. So if VCC&V_BCKP off and on, the Backup Mode setting is cleared. After a re-power on, the module goes back to Full On Mode( normal mode ).

If you want your settings remain after a completely power off or firmware upgrade, please use a PQ message.

Best regards.

Hello Rapael-Q,

Now it’s very clear. Thank you for your time for clarification!