Pytrack V_BCKP connection
Is V_BCKP (pin 6 of Quectel L76 GPS) connected to something on Pytrack ?
This pin, usually connected to very small battery (7µA conso) would enable standby mode when pytrack is in deep_sleep mode (where I guess VCC is off), or when pytrack is off.
Standby mode would enable 5s or 15s TTFF instead of 30s. This would save a lot of uptime !
As today I think it's done in pytrack.lib, looking at
go_to_sleepseems to set a PIC output, so my guess is it's connected to PIC PC7?
def go_to_sleep(self, gps=True): # enable or disable back-up power to the GPS receiver if gps: self.set_bits_in_memory(PORTC_ADDR, 1 << 7) else: self.mask_bits_in_memory(PORTC_ADDR, ~(1 << 7))
Tested and confirmed
go_to_sleep(gps=True)fix takes 1/2 seconds from wake from deep sleep and when
go_to_sleep(gps=False)is used fix takes much longer, may be same as first fix
Good to know
I'm facing the same issue, would be very helpfull having some schematics for this kind of questions.
Anyway did one of you succeed to enable V_BCKP to increase fix time on wake up from deep sleep?
May be stupid question, connecting V_BCKP to a I/O pin, then put this I/O High before deep sleep could to the trick ?
Well it's not connected to the PIC16, it seems to end on one pad of an unpopulated component - the pad NOT marked with +. The other side of that component (which is marked +) then connects to 3v3_Sensors.
I wonder what was supposed to be there - diode? - and/or why it was removed.
I think I see V_BCKP connected but not sure where to, possibly all the way to PIC16?
It seems after testing that L76 VCC and V_BCKP are not powered during deep_sleep.
So backup state is not possible as it is.
As 3v3_Pymodule is still on, would connecting V_BCKP to 3v3_Pymodule wouldn't be possible ?
That would make consumption of 18µA+7µA=25µA in deep sleep.