Can the Inland 3.5 Inch TFT LCD Touch Screen Monitor's backlight be turned off?

DanMG

I've got the monitor working on a Pi 3, but cannot find a way to turn off (or dim) the backlight. Does anybody know if it can be done (and if so, how)?

I'm currently using the tft35a binary overlay and just using it as a dumb memory mapped framebuffer - only my code needs to write to the display, so I don't need a kernel video driver and I'm not above hacking some code.

I couldn't find any backlight controls in the ILI9481 data sheet I found (an ILI9481 pdf file I found on the displayfuture website) but I'm no expert; the pin diagram I found (from waveshare, assuming this display is compatible) I didn't see anything that looked like a backlight enable.

I'm hoping for direct control that could even be dimmed with HW pwm. Any help or guidance would be much appreciated.

Aodhan_Gorman

I found this forum post about the IL19341 which is likely not exactly the same to the one Inland sell but may have some useful information to help further along your research. How to dim background LEDs on TFT display with ILI9341 - Arduino Stack Exchange

Alternatively, this is more of a hardware work-around as I am fairly new to the hobby electronics space, but I had to lower the brightness on a very basic LED light for a small project once by simply adding a resistor to the circuit to regulate the current running through my setup to prevent the bulb from dying. If it is possible to modify the power running to the backlight of this display, you may be able to solder a resistor between the power source and the backlight. This was, even in that scenario, more of a hack than the proper way to do it but just an idea on how it could be done.

DanMG

Unfortunately, the ILI9481 (a controller for 480x320 panels, like this one from Inland) doesn't have the Write Display Brightness (51h) that is available on the ILI9341 (a controller for 320x240 panels).

My electronics skills are quite terrible, so me adding a resistor will have the side effect of destroying the board. 😂 It's also not clear to me that a specific power pin is dedicated to the LEDs, though I'm beginning to suspect the LEDs are wired directly to some 5V pin...