AM6548: AM6548: LVDS Fading to black after bootup

Pierre Buffo

Part Number: AM6548
Other Parts Discussed in Thread: TMDX654IDKEVM

I'm having a very similar issue than: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1136409/am6548-lvds-fading-to-black-after-bootup

In my case I am able to keep the display alive as long as there's a valid SD card inserted. What I'm meaning by valid is that the SD card is electrically compliant, you really don't care about it's content. Each and every time I remove it the backlight goes off and the touchscreen doesn't work. But everything goes back to normal as soon as I plug another one. The issue only start when init is called. Last but not least, I'm using a micro-SD with an adapter to the legacy SD format, and fun fact is, if I only remove the microsd, but leave the adapter in the slot, the display keeps on !

I should also mention that I am working with the AM6548 EVK (IDK version) with the TI display kit.

LCD_BRD_TOUCH_INT and MMC1_SD_EN (reset manager for the SD card) signals are both connected to the same I2C GPIO expander (U7), coincidence ?

I have no clue about the origins of that problem, and if anyone has an idea it would be great.

Best regards
Pierre

PS. It is soooo annoying not to be able to reply to an old thread, this forum is full of redundant topics. Is it done purposely so that the number of topics grows massively ?

over 1 year ago

0 Kallikuppa Sreenivasa over 1 year ago

TI__Guru** 123008 points

Hello Pierre

Thank you for the query.

Pierre Buffo said:
I should also mention that I am working with the AM6548 EVK (IDK version) with the TI display kit.

Could you share the board version details.

Have you had a chance to revie the EVM user guide?

Is this a new board or have you been using this board for some time before seeing the issue.

How many bards do you have - in case you have more than 1 do you see the same issue on all boards?

Regards,

Sreenivasa

0 Pierre Buffo over 1 year ago in reply to Kallikuppa Sreenivasa

Prodigy 90 points

Hi Kallikuppa,

Here are the main board's details (PROCO62B)

Board OPN# TMDX654IDKEVM
PCB# 3P0014
ASSM# 001

I've had the board since a month (this is the only one I have), never saw the issue before, simply because I never tried to work without an SD.

Regards
Pierre

0 Kallikuppa Sreenivasa over 1 year ago in reply to Pierre Buffo

TI__Guru** 123008 points

Hello Pierre

Thank you for the inputs.

Let me check if we have received similar inputs previously from other customers with the team internally.

Regards,

Sreenivasa

0 Kallikuppa Sreenivasa over 1 year ago in reply to Kallikuppa Sreenivasa

TI__Guru** 123008 points

Hello Pierre

We are looking into the reported issue.

Would you mind confirming if you made the connections as shown below including the ground connections.

Could you please share a picture of the setup.

Regards,

Sreenivasa

0 Pierre Buffo over 1 year ago in reply to Kallikuppa Sreenivasa

Prodigy 90 points

Hi Kallikuppa,

Yes, although I'm not entirely sure what you mean by "ground connection". I've only got the large ribbon connected, looking at the schematics it also carries a ground connection. Please have a look at the pictures attached. The picture highlighting the screen will let you see that it is on, but the backlight isn't.