7" TFT LCD frame + touch supports PWM backlight control?

[hansan]

Dear support,

I am currently working on getting the touch screen of this LCD working on Angstrom.
While I was working on the kernel patch to activate the touch screen controller I noticed that there are quite some back-light related additions to the Andriod kernel code, but these do refer more to the OMAP3EVM.
The LCD part works well without this additions and on the expansion connector of the beagleboard looks only the SPI3.0 bus to be connected. (SPI3.0 is for the touchpanel controller) Only SPI3.1 CS pin would be usable as GPIO as far as I can see.

So my question is:
Is (PWM) controlled back-light supported on the Beagleboard XM?
And if so, which software is using this feature?

Kind regards,

Han

[esky-sh]

We will release a new cpld firmware for beadaframe PWM backlight control. At that time, you can use I2C3_SCL signal on P1 of NBD01 Rev.0 PCBA to switch on/off LCD backlight.

[hansan]

We will release a new cpld firmware for beadaframe PWM backlight control. At that time, you can use I2C3_SCL signal on P1 of NBD01 Rev.0 PCBA to switch on/off LCD backlight.

Can you explain a bit more in detail? Do I understand correctly that currently the backlight is always on?
Will I have to send a specific command (address + register value) to the I2C3 bus?
Does this functionality work by switching the PWR_EN pin 11 of P5 or is there some other way to switch the back-light on and off?

Do you advice me to add the back-light code in the Android kernel to Angstrom or would this not be needed? (I have to admit that i don't have the code in front of me now, so it can be that this questions doesn't make sense giving the fact that the back-light should be controlled by I2C and not through a PWM pin...)

By the way I think that using the Altera PLD is a very smart move: it solves the level conversion and it gives some routing and configuration freedom.

Is the in the schematic not mentioned and not populated connector is actually the JTAG connector for the CPLD?

For experimental purposes: Is it possible to get the .sof file to program the CPLD with the "factory" settings?
I assume that you do not plan to release the QuartusII project files. Or are those available as well?

I am sorry for so many questions. Many thanks!!

[esky-sh]

1. You can add a linux GPIO driver to drag the high/low level of I2C3_SCL signal on P1. This is a GPIO pin and there is no i2c support on your beada frame now.
2. Yes, we will finally release the firmware in .pof format.
3. We may post out our cpld design files in future, but it depends on various seen/unseen marketing factors and we can not make any promise to our customers now.

[hansan]

1. You can add a linux GPIO driver to drag the high/low level of I2C3_SCL signal on P1. This is a GPIO pin and there is no i2c support on your beada frame now.

Would it not be nice to add some I2C support to the beada frame? The Altera CPLD is supporting this, at least you can add an I2C Eprom as EDID device. And a I2C register to add a PWM counter and other functionality. The clock could come from the DVI_CLK, but this is not connected to a clock pin of the CPLD fabric (can give complications). An EPM570 should have enough logical blocks to do this all, and probably is an EPM240 also OK.

I will look into this after I have finished the Angstrom patch for the touch panel.

2. Yes, we will finally release the firmware in .pof format.

Thanks for that!!
Is the missing connector really the JTAG connector?

3. We may post out our cpld design files in future, but it depends on various seen/unseen marketing factors and we can not make any promise to our customers now.

I can very well understand if you don't want to release the complete CPLD design files.
But releasing the .POF or other programming file would be helpful in case I mix things up with my new CPLD firmware with I2C support.

[esky-sh]

1. You can add a linux GPIO driver to drag the high/low level of I2C3_SCL signal on P1. This is a GPIO pin and there is no i2c support on your beada frame now.

Would it not be nice to add some I2C support to the beada frame? The Altera CPLD is supporting this, at least you can add an I2C Eprom as EDID device. And a I2C register to add a PWM counter and other functionality. The clock could come from the DVI_CLK, but this is not connected to a clock pin of the CPLD fabric (can give complications). An EPM570 should have enough logical blocks to do this all, and probably is an EPM240 also OK.

I will look into this after I have finished the Angstrom patch for the touch panel.

Actually the new firmware design is done but we need to update software drivers on beagleboard. This will come out soon.

2. Yes, we will finally release the firmware in .pof format.

Thanks for that!!
Is the missing connector really the JTAG connector?

Yes