vbat.h File Reference

XMEGA VBAT system driver. More...

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Defines
Battery backup system status macros
#define	VBAT_STATUS_BBBOD   4
	A brown-out was detected on the VBAT input.
#define	VBAT_STATUS_BBPOR   3
	A POR was detected on the VBAT input.
#define	VBAT_STATUS_INIT   2
	The backup system must be initialized.
#define	VBAT_STATUS_NO_POWER   1
	No power detected on VBAT.
#define	VBAT_STATUS_OK   0
	Everything works as expected.
#define	VBAT_STATUS_XOSCFAIL   5
	A failure was detected on the oscillator.
Functions
void	vbat_enable_xosc (bool use1khz)
	This function starts the crystal oscillator with 1 or 1024 Hz clock output.
void	vbat_reset (void)
	This function resets the battery backup module.
uint8_t	vbat_system_check (bool first_time_init)
	Check battery backup system status.

---

Detailed Description

XMEGA VBAT system driver.

Application note:

AVR1321: Using the XMEGA 32-bit RTC and battery backup system

Documentation

For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html

Author:

Atmel Corporation: http://www.atmel.com
Support email: avr@atmel.com

Revision

112

Date

2009-11-18 14:31:39 +0800 (WED, 18 Nov 2009)

Definition in file vbat.h.

---

Define Documentation

#define VBAT_STATUS_BBBOD   4

A brown-out was detected on the VBAT input.

The backup system is in a unkown state and must be reset.

Definition at line 94 of file vbat.h.

Referenced by main(), and vbat_system_check().

#define VBAT_STATUS_BBPOR   3

A POR was detected on the VBAT input.

This means the backup system is in an unkonw state.

Definition at line 87 of file vbat.h.

Referenced by main(), and vbat_system_check().

#define VBAT_STATUS_INIT   2

The backup system must be initialized.

A POR was detected on VBAT input which indicates that a supply was connected to the backup system. Since this is also the first start-up of the device we then need to initialize the backup system.

Definition at line 80 of file vbat.h.

Referenced by vbat_system_check().

#define VBAT_STATUS_NO_POWER   1

No power detected on VBAT.

The backup system is not operational and all data within the backup system will be lost when main power is lost.

Definition at line 71 of file vbat.h.

Referenced by main(), and vbat_system_check().

#define VBAT_STATUS_OK   0

Everything works as expected.

The backup system is configured and had no issues while main power was lost. Because of that all data stored in the backup domain is valid.

Definition at line 63 of file vbat.h.

Referenced by main(), and vbat_system_check().

#define VBAT_STATUS_XOSCFAIL   5

A failure was detected on the oscillator.

The oscillator stopped for at least TBD period of time and because of that we can not rely on the RTC time any more.

Definition at line 101 of file vbat.h.

Referenced by main(), and vbat_system_check().

---

Function Documentation

void vbat_enable_xosc

(

bool

use1khz

)

This function starts the crystal oscillator with 1 or 1024 Hz clock output.

Parameters:

use1khz

Boolean for selecting 1 kHz or 1 Hz RTC clock rate.

Definition at line 27 of file vbat.c.

Referenced by vbat_init().

{
        // Enable the failure detection.
        VBAT.CTRL |= VBAT_XOSCFDEN_bm;

        /* A delay is needed to give the voltage in the backup system some time
         * to stabilise.
         */
        delay_us(200);

        // Enable oscillator, with 1 kHz or 1 Hz output.
        if (use1khz)
                VBAT.CTRL |= VBAT_XOSCEN_bm | VBAT_XOSCSEL_bm;
        else
                VBAT.CTRL |= VBAT_XOSCEN_bm;
}

void vbat_reset

(

void

)

This function resets the battery backup module.

This function will also set the access enable bit for the control register.

This function will set the access enable bit for the control register.

Definition at line 9 of file vbat.c.

References ENTER_CRITICAL_REGION, and LEAVE_CRITICAL_REGION.

Referenced by vbat_init().

{
        // Enable R/W access to the battery backup module.
        VBAT.CTRL = VBAT_ACCEN_bm;

        // Reset the module. (Reset bit is protected by CCP.)
        ENTER_CRITICAL_REGION();
        CCP = 0xD8;
        VBAT.CTRL = VBAT_RESET_bm;
        LEAVE_CRITICAL_REGION();
}

uint8_t vbat_system_check

(

bool

first_time_init

)

Check battery backup system status.

Parameters:

first_time_startup

When this is the first time the system starts then this is false otherwise true.

Returns:

Backup system status.

Definition at line 44 of file vbat.c.

References VBAT_STATUS_BBBOD, VBAT_STATUS_BBPOR, VBAT_STATUS_INIT, VBAT_STATUS_NO_POWER, VBAT_STATUS_OK, and VBAT_STATUS_XOSCFAIL.

Referenced by main().

{
        uint8_t vbat_status;
        /*
         * Check if sufficient power was detected on the VBAT input. The brown-
         * out detector (BBBOD) will be sampled once when the device starts up
         * and the result is visible as the BBPWR flag.
         */
        if (VBAT.STATUS & VBAT_BBPWR_bm)
                vbat_status = VBAT_STATUS_NO_POWER;
        else {
                /*
                 * We hav sufficient power, now we check if a power-on-reset
                 * (BBPOR) was detected on VBAT. This is visible from the BBPORF
                 * flag which is also only updated once when the device starts.
                 */
                if (VBAT.STATUS & VBAT_BBPORF_bm) {
                        if (first_time_startup)
                                vbat_status = VBAT_STATUS_INIT;
                        else
                                vbat_status = VBAT_STATUS_BBPOR;
                }
                else if (VBAT.STATUS & VBAT_BBBORF_bm)
                        vbat_status = VBAT_STATUS_BBBOD;
                else {
                        VBAT.CTRL = VBAT_ACCEN_bm;
                        if (VBAT.STATUS & VBAT_XOSCFAIL_bm)
                                vbat_status = VBAT_STATUS_XOSCFAIL;
                        else
                                vbat_status = VBAT_STATUS_OK;
                }
        }
        return vbat_status;
}