several wake up gpio interrupt

[Tai]

Hi everybody!

We have a problem with our product. It is based on nrf52832.

We used heart rate example in the SDK. MCU sleeps after a while if it is not connected. We have a touch switch and the switch wakes up the MCU. On the other hand ther is a battery and a battery charger. We need to use USB detection and the switch as waking up interrupt. 

Does anybody know if it is possible? Which sleep mode should we use?

Thanks 

[Håvard]

Hi Tai, unfortunately, your description is a bit unclear to me. You have an nRF52. It goes to sleep. There is a switch that wakes up the chip. There is also a battery and a charger somewhere, but how do they relate to the switch? Is the switch just a high signal to a gpio, like a button on the devkit? Or does the switch do more? Are there two different wake up sources? Two different power sources? (Withouth the battery, is the chip powered at all?)

The nRF52832 does not have a USB peripheral. 

The nRF52840 does, and can use it to wake from SYSTEM OFF.

In either case, "sleep mode" mode you would be looking to go from is SYSTEM OFF.

If you look at the link above, I'm sure you can attach some hardware to detect the battery using a gpio, or the low power comparator.

In addition to the button 1 (default to wake up our BLE examples), you can set up other events as wake-up sources. See threads like these:

https://devzone.nordicsemi.com/f/nordic-q-a/19859/system-off-and-gpiote/77243#77243.

https://devzone.nordicsemi.com/f/nordic-q-a/36475/nrf52832-go-system-off-low-power-mode-and-wakeup-by-gpio/140687#140687

[Tai]

Hi Havard,

Thanks for your reply. 

I have a nrf52832 with a battery. I used a button to GND like the button of thingy 52 to wake up the circuit. I have not used any pull-up or pull-down for this button. So I need to sysem off and wake it up with this button.

Moreover, I have a battery charger working with a USB port. The nrf52832 recives a signal when the USB is plugged in. I need to wake up the MCU in this case as well to manage charging process and LEDs.

Is it possible to wake up the nrf52832 with two signals: 

1- Button to GND without pull

2- High signal from USB port

[Tai]

Anybody has an idea?

Is it possible to use several GPIOs for waking up without pull-up or pull-down?

[Dmitry]

Hi,

you can use several GPIO to wake up - call nrf_drv_cfg_sense_input() with NRF_GPIO_PIN_SENSE_LOW or NRF_GPIO_PIN_SENSE_HIGH, whatever you need, for both pins.

If you have no external pull-up, you should enable internal one, the button won't work without pull-up.

[Jørgen Holmefjord]

Hi,

You should be able to configure any GPIO with either LOW or HIGH SENSE functionality before going to System OFF mode:

Please have a look at the documentation of nrf_gpio_cfg_sense_input().

Best regards,
Jørgen

[Tai]

Thanks Jørgen for your relpy.

My question is: if we do not use external pull-up or down resistor at a GPIO, is it possible to use LOW or HIGH SENSE to wake up the MCU? I mean can we use internal pull-up or down resistor during system off?