Is there any way to vary the backlight on this display? I looked at the datasheet but there doesn't seem to be any information regarding the backlight...
The backlight enable input is configured to be used with PWM to vary the brightness.
At least, that's how it compares to the AP3031 datasheet.
looking @ A20-OLinuXino-Mcro.pdf the pin outs of the LCD connector its not too clear which is the PWM for the LCD I only see H/V Sync, power, DE, data 0-23 - I assume PB2/PWM0 isn't part of the LCD connector???
There seems more than just the pins needed for the display on that connector?
If I can identify which pin is used for PWM I'm up for writing a simple C application to change the PWM rate (I can't see it being that hard... famous last words!!!)
not used to be spoilt by such luxuries as circuit diagrams and everything!
(https://www.olimex.com/Products/OLinuXino/A13/A13-LCD7-TS/resources/A13-LCD7_sch.pdf)
anyhow it is the PWM0 (pin 36) thats connected to a ap3031 to drive the led's
(http://www.datasheet4u.net/download.php?id=660005)
However instead of being connected to the ctrl pin as I'd have expected its connected to the vref pin, is it intended to vary brightness via a pwm signal on the vref?
(edit: more accurately voltage feedback not ref!)
ironically the datasheet I linked to for the backlight driver was much better than the 2 page pamphlet I was reading!
turns out modulating Vfb is fine (and suggested as well as cntl)
all I have to do is read up on PWM0 - but the wife to be insists on watching football - so I'm off to the pub!
Good detective work. It's great when someone takes the time to read the datasheets! :)
PB2 is indeed the control line for the brightness. LCD_PWR controls the LCD and backlight power on/off, which I have found really does make a difference when in low power state. At least on battery it does. When on external power, it just dims the backlight unless you press the power button to put it to sleep.
You get to go to the pub and watch football and with your wife to be!! Lucky man. I have to watch my sport at home via a streaming feed as not many channels broadcast it live here anymore (Aussie V8 Supercars) :)
NO !
*she* watches that rubbish so I *have* to go to the pub!
I have lcd brightness working I'll post a howto seperatly