iMX233:Selcting powersource for booting

[sujathap_m_]

Hello,

I'm finding conflict in selecting power source for booting the device.

If both 5V source and Battery is valid during booting,It is booting from battery itself.But we wanted to boot from 5V source,even though Battery is valid.

How can we do this?Which files should be edited?

Regards,

Sujatha

[GraceH]

Hi Sujatha,

We have done this in i.MX28 L2.6.35.1.1.0 release,

You can modify function PowerPrep_ConfigurePowerSource of power_prep/power_prep.c of bootlet.

Regards,

Grace

[sujathap_m_]

Hello Grace,

We are using i.MX233 EVK and BSP L2.6.31_10.05.02.

During the system (i.MX233 EVK) operation, if the battery is completely discharged, the system is turning OFF due to low battery. When the Device is OFF with the discharged battery, if the external USB charger is connected, the system turns ON and starts taking again the power from Battery (which is already having very low charge). Due to the very less charge availability on the battery, the system goes OFF and reboots again and again till the time the USB 5V is present. In this case, booting is never successful.

With the Battery and USB 5V connected at the same time, How can I configure the system to boot from USB 5V only and charge battery at the same???

If I define NO_BATTERY_VOLTAGE_SOURCE in power_prep.c ,system always boot from 5v source,never switch back to battery once if we unplug the usb and cannot charge the battery from USB.

Regards,

Sujatha

[GraceH]

Hi Sujatha,

You can't define NO_BATTERY_VOLTAGE_SOURCE in power_prep.c. It is for the system which has no battery, but only 5V.  You need modify function PowerPrep_ConfigurePowerSource of power_prep/power_prep.c.

You can reference power_prep.c of i.MX28 L2.6.35.1.1.0 release,

if(!IsVdd5vGtVddio())

{

.....

iReturnValue = PowerPrep_BattBoot();.

......

}

else

{

/* 5v input detected, boot from 5V. */

...

iReturnValue = PowerPrep_5vBoot();

...

}

Grace

[sujathap_m_]

Hello Grace,

What exactly I should edit in function PowerPrep_ConfigurePowerSource of power_prep/power_prep.c ?

Why is the system taking the power from  Low Battery when the external USB 5V is connected???

Our target application is a media player, which runs on Li-Ion battery. If the battery is discharged completely, the system will be put in shutdown. Once the USB 5V is plugged, the system should be able to boot up properly and charge battery till the time the external 5V is connected. Is this configuration possible on i.MX233 platform??

If is possible How to do that?

Regards,

Sujatha

[GraceH]

Hi Sujatha,

You can copy function PowerPrep_ConfigurePowerSource from i.MX28 L2.6.35.1.1.0 release.

Grace

[sujathap_m_]

Hello Grace,

I have made changes on function PowerPrep_ConfigurePowerSource , still problem is existing,after sometime it handovers to Battery itself.

Our problem is : If the battery is completely discharged, the system is turning OFF due to low battery. When the Device is OFF with the discharged battery,if the external USB charger is connected, the system turns ON and starts taking again the power from Battery (which is already having very low charge). Due to the very less charge availability on the battery, the system goes OFF and reboots again and again till the time the USB 5V is present. In this case, booting is never successful.

I have checked the function ddi_power_init.c in mach_mx23/driver/power , 5V IRQ is not initialized(condition is commented).why it is like that?If we connect 5v source,will interrupt is generate?

Regards,

Sujatha

[Yuri]

According to Table 2-3 (Recommended Power Supply Operating Conditions)

of the i.MX23 Reference Manual, Battery / DCDC Input Voltage - BATT, DCDC_BATT should be

in range 2.6 - 4.242 V. This means that dead battery is not allowed. In any case DCDC_BATT must

be greater than 2.6 V.