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I am having real problems with installing my LCD (having searched endless youtube videos and websites, yet nothing seems to work).

I bought this: http://www.ebay.co.uk/itm/172293077369?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

It doesn't have any branding on the back, even though the picture displays HVGA.

I get a white screen and nothing else.

I have tried this: http://www.waveshare.com/wiki/3.5inch_RPi_LCD_(A)

but think its not going to work because thats a different brand?

Any advice? thanks

  • 1
    Have you tried the waveshare instructions? They are likely to work. Second, as a lesson, you should remember that you get what you pay for. One of the things missing with cheap parts are instructions and tech support - these are especially import for those new to electronics/the Pi. – Steve Robillard Jun 15 '17 at 2:05
  • I did try waveshare - but there isn't any specific for Pi Zero. You are right about the latter part :( – user1472266 Jun 15 '17 at 8:32
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    I think you might want to take the "30 days - Seller pays return postage" option! Without details of the API/interface to access it you are going to be hamstrung IMHO... Also I suspect that a single SPI (serial) data channel is not likely to really make it "...an ideal alternative solution for HDMI monitor..." for anything other than a largely static displays because of the bandwidth necessary to transfer all the data that forms even a 320*480 display (say there is four bits for each of R/G/B channels that is 320*480*4*3@50 or 1,843,200@50Hz or 92,160,000 bit/s without sync/timing stuff)! – SlySven Jun 15 '17 at 16:28
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I have one of those displays, also purchased from a discount seller on ebay. It's a clone of a clone of Adafruit's display, but it works identically. You can find setup instructions that work here:

https://www.raspberrypi.org/forums/viewtopic.php?f=46&t=148678

You just need to get the waveshare35a dtoverlay file and reference it in /boot/config.txt.

The display will work on the RPi Zero, B+, 3B (I have those 3 types of boards and tested it on all of them). This particular display may disappoint you if you're going to use it for high framerate activities like video playback or gaming. The SPI interface on the board talks to relatively low speed shift registers and maxes out at 12-16Mhz. For a 320x480x16-bit display, this means frame rates of 10fps or less. If you don't mind this limitation, then it's a decent little display. When plugged in and no software to talk to it, it will just show a blank white screen. The backlight LED is just connected to a logic level and cannot be dimmed.

Once you have it set up with the dtoverlay, it still won't display anything because the dtoverlay creates a virtual frame buffer at /dev/fb1. If your software doesn't know to send it's output there, you can configure Linux to use it as the main display. You can also just talk directly to the display and bypass the normal 'Linux' way of dealing with framebuffers. I've published C code which talks directly to this type of display:

https://github.com/bitbank2/SPI_LCD

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  • Hey, appreciate this so much - I'm going to have a go at it now :) – user1472266 Jun 24 '17 at 14:12
  • Hi @BitBank, I went through the tutorial here raspberrypi.org/forums/viewtopic.php?f=46&t=148678 on a fresh install - unfortunately, its still doing the same, its a white screen. I also tried your c code and done the make sample file, and I tried to run the lcd file but nothing happened. I appreciate I am well out of my depths here ha – user1472266 Jun 24 '17 at 14:53
  • Have you enabled SPI? You can do it from raspi-config or from the /boot/config.txt file. – BitBank Jun 24 '17 at 15:24
  • Yup, from the tutorial: dtparam=spi=on – user1472266 Jun 24 '17 at 15:44
  • The only other thing I can think of is to lower the SPI frequency until it works. That particular display uses slow shift registers. Try setting it to 5Mhz as a starting point and see if that gets it going. If it works, raise the speed until you get to the point it stops working. Did you try the touch controller part? If that part works, it could indicate a problem with the LCD controller and not your SPI communication. – BitBank Jun 24 '17 at 16:01

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