VBUSVALID and VDD5V Brownout configuration (IMX28)

[dgotfroi]

Hello,

Can you please tell me, how and where can I configure VBUSVALID voltage and VDD5V Brownout voltage ?

I read the AP AN4199 "Using the i.MX28 Power Management Unit and Battery Charger", and it said :

"VBUSVALID

The threshold value for a valid 5-V status is configured in the software, and the default value is 4.4 V on the Linux BSP. "

and

"VDD5V Brownout

The VDD5V-source

brownout level is a voltage threshold and is an absolute voltage value as in the case of a battery brownout.

There are four available settings for VBUS droop brownout:

• 4.3 V

• 4.4 V

• 4.5 V

• 4.7 V

Each setting has a 50-mV hysteresis to prevent chattering. It is set to 4.5 V in the Linux BSP "

But I would like to know in which file do i need to make the modifications ?

Many thanks in advance.

[igorpadykov]

Hi Damien

these voltage thresholds are described in

sect.11.12.2 i.MX28 Reference Manual (rev.1, 9/2010)

VBUSDROOP_TRSH, VBUSVALID_TRSH

http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf

In Linux one can find them in bootlets (ddi_power_5v_detect.c).

For obtaining bootlets sources:

1. ./ltib -m prep -p imx-bootlets

This command will put imx-bootlets source codes in the folder --

ltib/rpm/build/

2. modify sources

3. ./ltib -m scbuild -p  imx-bootlets

This command will build new images.

Best regards

chip

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[dgotfroi]

Many thanks for this answer.

But I use Yocto with Bitbake and not LTIB.

How can I do that with bitbake ?

Many thanks

[igorpadykov]

Hi Damien

there are tons of materials for yocto build, please start

with below

https://community.freescale.com/docs/DOC-94023

I would suggest to create new thread for

yocto questions since they are specific ones.

Best regards

chip