Wake up trigger design

[sasci]

Hello, 

I developed low power device. I'm using external wake up timer the TPL5111. But this IC output not enough for my device wake up. So I decide add new component (N channel mosfet). Currently I don't know how to wake nrf with this mosfet. Here is the circuit I used that before use timer.

so my question is how to do trigged for n channel mosfet?

[Bendik Heiskel]

Hi,

Can you explain a little more about what configuration you want to use?

Do you want to use the TPL511 and the mosfet to switch the VDD for the nRF52840?

Or do you want to use the TPL511 and a GPIO pin on the nRF52840 to wake the device from sleep?

If this is the case it seems like the TPL511 could be used without needing a mosfet.

 

Best regards,

Bendik.

[sasci]

Bendik Heiskel said:

Or do you want to use the TPL511 and a GPIO pin on the nRF52840 to wake the device from sleep?

Yes, I want to do this.

I have to use timer for self wake up. I try this situation but doesn't wake up. So I tried wake up  with GPIO pin as in this link. TPL5111 output pin voltage is about  3V. But when I directly connect the Timer pin and GPIO pin it does not wake up. If I don't use mosfet, how to do this? 

[sasci]

This is the circuit I tried. Maybe it helps.

[Bendik Heiskel]

What is the VDD voltage for the nRF52840? If it is 3V then the output from the TPL5111 is enough to register as logic high. The minimum voltage for logic high is VDD-0.3, so a VDD voltage of 3.3V should also work.

[sasci]

Bendik Heiskel said:

What is the VDD voltage for the nRF52840?

between 3V-3,7V

Already TPL output voltage is no problem. But I want to trigger it using wake pin not VDD

configure_gpio_wakeup(uint32_t pin_number, nrf_gpio_pin_sense_t sense)

{

nrf_gpio_pin_latch_clear(pin_number);

nrf_gpio_cfg_watcher(pin_number);

nrf_gpio_cfg_sense_set(pin_number, sense);

}

If this is true, is this true too?

configure_gpio_wakeup (11, NRF_GPIO_PIN_PULLUP);

When I'm using this codes, why can't I trigger with TPL5111 output.  I'm waiting for help on this.

[Bendik Heiskel]

Sorry for not getting back to you sooner, have you made any progress?

Since the the TPL pulls the GPIO line high the sense option should be:

configure_gpio_wakeup (11, NRF_GPIO_PIN_SENSE_HIGH);

You can also use the BSP library to wake the device up from a GPIO signal:

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/examples_bsp_btn_ble.html?cp=8_1_3_6_1

The Power Management Example shows how to use this library:

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/pwr_mgmt_example.html?cp=8_1_4_6_21

[sasci]

You're late. When he didn't answer, I sent the circuit board to production. Because project final day came. I use that first mentioned your. But a little bit different :). Mosfet triggers ground instead of power. Thank you :)