XMC4800 – hibernate questions

[User19967]

Hi,

I read some document and some post about hibernate but I’m a bit confused.

I want to run XMC in hibernate domain when no VDDP is supplied, (I want to run only the RTC when xmc is hibernate).

I use DaveApp and I added to my project a RTC app. RTC work properly if i don’t remove the VDDP.

When I remove VDDP (Vbat is supplied) i don’t know if xmc is “power off” or hibernate, when VDDP is supplied again the RTC lost the date/time.

The pin HIB_IO_1 and HIB_IO_0 are disconected.

Some questions:

• If I want to hibernate by removing VDDP, there are any hardware connection for HIB_IO_1 or HIB_IO_0 mandatory?
• What I have to add to my code to enable the hibernate?
• I have to put this code after or before the dave_Init?
• When the xmc wake app, it start with a new main loop? Every wake up do the dave init?

Thanks for your support

Oscar

[Vasanth]

Hi Oscar,

How are you enabling Hibernate mode as of now? Meanwhile check the XMC Lib code for reference.

Additionally kindly check section 11.4.1 in user reference manual.

External Voltage Regulator is controlled from Hibernate domain and VDDP gets switched
off when hibernate mode is entered. No reset of hibernate control occurs in hardware
upon power-up but the chip will boot up as normal since in this mode no internal state of
the chip is affected except for the hibernate control pin from hibernate domain to the
External Voltage Regulator. Re-initialization of is possible with software upon boot-up.

Best Regards,
Vasanth

[Vasanth · Accepted solution]

Hi Oscar,

Additionally regarding the pins see the following section 11.4.3 in reference manual,

The Externally Controlled Power Supply scheme require external devices on in order to fully support power management related functions. The external power supply needs to support on/off control of the VDDP voltage
generation. This scheme enables the XMC4700 / XMC4800 e.g. to control supply voltage for multiple on-board devices. A simple power control scheme assumes availability of two pins - HIB_IO_0 and
HIB_IO_1 as shown in Figure. If the External Voltage regulator implements low active (enabled with low) power control then it can be reliably controlled with HIB_IO_0 pin, which by default is set to open-drain and ensures proper driving value from the moment a valid VBAT voltage gets applied. A wake-up signal can be supplied externally via HIB_IO_1 pin or internally generated with from RTC module.

[User19967]

Dear Vasanth,

thank you for your kind response.

Sorry if it took me so long to answer.

I have few more questions:

XMC4800 – How can I achieve what you described using an external voltage regulator with enable active high?

XMC4200 (I know it isn’t the right topic, but I hope you can still answer) – Has a single pin HIB_IO (HIB_IO_0). How can I achieve the same result with these characteristics: external voltage regulator with enable active high, and an external wake up trigger (i.e. push button)?

How can I set a HIB_IO pin as a bidirectional pin?

Best Regards,

Oscar

[Vasanth]

Hi Oscar,

1. XMC4800 – How can I achieve what you described using an external voltage regulator with enable active high?

Kindly check the HDCR Hibernate Domain Control Register,HIBIO0POL and HIBIO1POL control the output polarity of the HIBIO0 and output polarity of the HIBIO1 respectively.

2.XMC4200 (I know it isn’t the right topic, but I hope you can still answer) – Has a single pin HIB_IO (HIB_IO_0). How can I achieve the same result with these characteristics: external voltage regulator with enable active high, and an external wake up trigger (i.e. push button)?

See the corresponding sections in the 4200 reference manual

After power up and before entering Hibernate mode the HIB_IO_0 needs to be reconfigured to bidirectional (but still open-drain driver) mode. Hibernate mode activation automatically changes state of the HIB_IO_0 output to high impedance which allow the external pull up resistor to drive high value of the External Voltage Regulator in order to switch off VDDP generation. 

Best Regards,
Vasanth