nRF9160 Sleep mode plus TWIS and LPUART

[WesC]

i am trying to determine the current consumption of the nRF9160 when in sleep mode but running LPUART and TWIS.

I see that the Sleep mode (MCU IDLE, MODEM off, RTC on) shows about 2.2uA in the PS.

if i need to wake from a LPUART or TWIS interface  how much current will the nRF9160 use with these peripherals in idle state.

I cannot find the Electrical Specifications showing current consumption of these peripherals in IDLE states.

also, If I have the MODEM on and in PSM, does that add 2.7uA or is the total SIP at 2.7uA.

if the total SIP ( i would assume the APP CPU is IDLE?)

[Stian Røed Hafskjold]

Hi, sorry for the late response.

The LPUART uses GPIO PORT event which is not consuming any additional current.

The TWIS senses for a start condition on the two pins so it will consume current in the 20 uA range

The total SIP consumption in PSM mode is 2.7uA. It includes the modem side, and the application in sleep mode. Which is application CPU idle, and RTC+LF clock running (app timers). So in this mode the modem is sleeping waiting for the next PSM wakeup, and the application is sleeping but able to wake up on any application timer interrupt.

[WesC]

I guess just to verify that i understand.  

the LPUART will use no current until there is activity on the GPIO.

then it will wake the CPU from Sleep and use the active current until complete

and the TWI will consume 20uA continuously

[Stian Røed Hafskjold]

Hi, I discussed this further with the LPUART developer, and they actually use GPIOTE IN event for the interrupt on UART RX (not the GPIO PORT event). So unfortunately the LPUART is consuming about 20 uA in idle as well (same as TWIS). I asked the developer to fix this, and this is on the todo list. They will use the GPIO PORT event instead, which do not consume any extra current, but this has not been implemented yet as this requires changes in the low level GPIO driver in Zephyr.

Yes, the TWIS will consume 20 uA continuously.

Sorry for the confusion.