AM3359: Pixel Clock verification

David Faulkner

Part Number: AM3359
Other Parts Discussed in Thread: SN75LVDS83B

I am using the Beaglebone Black with SDK Ver 3.03.00.004. I found an EMC issue that appears to be coming from the pixel clock at 65, 130 and 195Mhz. The LCD I am using is G104X1-L03 paired with the SN75LVDS83B IC. I measured the clock with my oscilloscope and it appears to be 65 Mhz which is the nominal frequency for the display. I just assumed that 130 and 195 MHz were harmonics from that clock, though I would like to confirm that.

My questions are:

How can I determine the pixel clock real frequency?

Where would the lcd driver likely be stored? I looked in the driver folder but could not find it.

Is there a way I can change the frequency through the command line without having to modify the driver?

Thanks

over 4 years ago

0 Krunal Bhargav34 over 4 years ago

TI__Mastermind 45015 points

Hello,

I am not sure which PSDK you are currently using. In genera,l the LCD driver is located in the following location: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/drivers/gpu/drm/tilcdc?h=ti-linux-4.19.y. Also, here is an example of how you would define your LCD configuration: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm/boot/dts/am335x-evmsk.dts?h=ti-linux-4.19.y#n188. Also, the default driver does not allow you to change frequency through command line.

Regards,

Krunal

0 David Faulkner over 4 years ago

Prodigy 20 points

Hello Krunal,

Sorry but what is a "PSDK"?

0 Krunal Bhargav34 over 4 years ago in reply to David Faulkner

TI__Mastermind 45015 points

Hello,

PSDK stands for Processor Software Development Kit and TI releases a PSDK every year. I would recommend you to review the release notes to better understand the latest Kernel/Uboot versions supported by TI.
Ref. Link 1: https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/AM335X/linux/Release_Specific_PLSDK_Release_Notes.html#release-06-03-00

Ref. Link 2: https://www.ti.com/tool/download/PROCESSOR-SDK-LINUX-AM335X#release-notes

Also, please keep in mind that we only support TI tested Kernel/Uboot and we do not support Debian OS.

Regards,
Krunal

0 David Faulkner over 4 years ago in reply to Krunal Bhargav34

Prodigy 20 points

As stated above, the SDK version is 03.03.00.004. Does that driver example you provided still apply for this version?

0 Krunal Bhargav34 over 4 years ago in reply to David Faulkner

TI__Mastermind 45015 points

Hello,

Unfortunately, we do not support SDK version 03.03.00.004. I would recommend you to review the DTS file and review the LCD configuration for one of our boards.

Regards,
Krunal

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AM3359: Pixel Clock verification