<https://lh3.googleusercontent.com/-NW_qX1Cz0Vk/VVzTguPp-RI/AAAAAAAADKs/NIVwCCQ1PLM/s1600/Screen%2BShot%2B2015-05-21%2Bat%2B02.25.52.jpeg> Hi there folks,
The CircuitCo LCD3 cape version A2 basically pulls up the backlight supply enable line via R126. By removing R126, and adding a 0R resistor (or a blob of solder) on the pads for R123, you enable use of the EHRPWM1A line to control the backlight. The caveat is that when you power up the BBB, you should issue a echo 50 > /sys/class/backlight/backlight/brightness to have anything come up on the BBB LCD3. Cheers! - Antonio On Friday, 30 May 2014 02:43:06 UTC+8, john3909 wrote: > > > From: Colin Bester <[email protected] <javascript:>> > Reply-To: <[email protected] <javascript:>> > Date: Thursday, May 29, 2014 at 6:45 AM > To: <[email protected] <javascript:>> > Subject: Re: [beagleboard] BBB LCD3 Cape and inactivity > > I just managed to get around to looking a little deeper into this and > connected an oscilloscope to EHRPWM1A (which I figure is pin P9_14) and > confirm that when writing a zero to brightness (using echo 0 > > /sys/class/backlight/backlight.11/brightness) that the pin is low. Likewise > write a ’50’ sets a 50% duty cycle and LCD brightens. I haven’t set up > environment to compile and test using ‘c’ files yet. > > With low on pin P9_14 the LCD is still visible. > > In that case this is a hardware issue. P9_14 is connected to the enable > pin of the LED backplane driver so the leds should turn off. > > Regards, > John > > > With debian version I now have running, I have not seen the LCD goto sleep > yet - still have to look into this. > > ~C > > > On May 26, 2014, at 8:03 PM, John Syn <[email protected] <javascript:>> > wrote: > > > From: Colin Bester <[email protected] <javascript:>> > Reply-To: <[email protected] <javascript:>> > Date: Monday, May 26, 2014 at 4:54 PM > To: <[email protected] <javascript:>> > Subject: Re: [beagleboard] BBB LCD3 Cape and inactivity > > Was wondering if you have come up with any further solution? I can write > '0' to backlight brightness but while this dims the display significantly > it doesn't switch if off. > > Have you checked that EHRPWM1A is low when you dim the display? Here are > two files that will control the backlight. > > /driver/video/backlight/pwm_bl.c > /driver/pwm/pwm-tiehrpwm.c > > Regards > John > > > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
