STM32F746 Discovery - No PWM control of LCD backlighting

[jon2]

Posted on December 09, 2016 at 01:50

It looks like LCD_BL_CTRL is not connected to a PWM output-capable pin (PK3)?  Am I missing something?

[Imen.D]

Posted on December 09, 2016 at 09:32

Dear

Magnussen.Jon

‌,

Following the schematic in the

http://www.st.com/content/ccc/resource/technical/document/user_manual/f0/14/c1/b9/95/6d/40/4d/DM001904pdf/files/DM001904pdf/jcr:content/translations/en.DM001904pdf

LCD_BL_CTRL is connected to PK3.

Could you please check this from your side andclarify more your feedback?

Best Regards

-Imen-

[jon2]

Posted on December 09, 2016 at 13:28

Yes, I mentioned that pin in my post.  However, it doesn't appear to be PWM capable, so it can only control on/off.

[ST Renegade]

Posted on December 09, 2016 at 21:37

It appears you are right. The pin is not connected to Timer... Maybe it would be possible to connect the PK3/LCD_BL_CTRL to a timer output on the board using a jumper wire or so.

Have a nice day,

Renegade

PS: Maybe you can use DMA to transfer data to the GPIO output and create your own PWM out of it triggered by some timer or so if you prefer SW solution.