Can watchdog wake up BlueNRG-2 from deep sleep?

[Piotr Romaniuk]

Posted on May 14, 2018 at 12:00

Hi,

I would like to know if watchdog can wake up BlueNRG-2 chip from deep sleep?

Is watchdog powered and has active clock in this sleep mode?

Kind regards,

Piotr Romaniuk

#bluenrg-2 #watchdog

[Winfred LU]

Posted on May 15, 2018 at 09:08

Hi Piotr,

The watchdog peripheral does not work in Sleep or Standby mode, because in these modes the digital power is not supplied (except the power necessary to keep the RAM in retention).

Please use SLEEP_MODE_CPU_HALT mode instead, using this power saving mode the current consumption is around 1.5 mA.

Please reference the project:

<BlueNRG-1_2 DK 2.6.0>\Project\BlueNRG1_Periph_Examples\WDG\Wakeup

Thank you.

Best Regards,

Winfred

[Piotr Romaniuk]

Hi Winfred,

I found more information on this topic in the documentation of the chip:

1) There is a small difference between SLEEP and STANDBY state: in sleep state slow clock is running but in standby it is not

2) Watchdog is clocked by this slow clock

3) Watchdog RST line is connected to a gate as equivalent input to BLE RSTs line, while BLE RST can be activated by RESET pin.

These are only observations and conclusions from the documentation, and I did not verified it in circut, but:

a) if RESET pin can wake up the chip, it does it by BLE RSTs line

b) BLE RSTs line and WDG RST are symetric input of the gate, so WDG RST can reset the chip as well

c) Watchdog is clocked from slow clock that is running in SLEEP state

Does it mean that watchdog can wake up the chip from SLEEP state?

Regards,

Piotr Romaniuk

[Winfred LU]

Hi Piotr,

Sorry for the late. I did not notify the previous response.

No, watchdog cannot be a wake up source.

In either SLEEP or STANDBY mode, digital power supply is switched off,

so the digital components including watchdog are not functioning.

Best Regards,

Winfred