Closed potato closed 6 years ago
You can use it on a PI Zero so long as you supply enough power. There's projects that use a 3.5in screen and a Pi Zero.
Some of these screens show up faulty. My original one did, the edge connector for the screen's board wasn't soldered properly. All i did was heat up the solder and watched it fall into place.
Thanks for the reply, the screen is not faulty, I tried the exact same screen with my pi 2, and it worked. I used the pi zero with an 1.5A external power source, I think it should be enough for it.
I also used spidev_test.c to make sure the zero's spi pins are okay. It gave me the expected result, so at least the MISO, MOSI pins are working correctly.
I don't know of anything that should prevent it from working. Have you checked that the driver is loaded and probed?
$ dmesg | grep graphics
[ 39.727869] graphics fb1: fb_st7789s frame buffer, 240x320, 150 KiB video memory, 0 KiB buffer memory, fps=20, spi0.0 at 25 MHz
right now with the configuration from the last try (with waveshare-dtoverlays) I got this:
[ 11.269036] graphics fb1: fb_ili9486 frame buffer, 480x320, 300 KiB video memory, 32 KiB DMA buffer memory, fps=33, spi0.0 at 16 MHz
the relevant lines from my config.txt:
dtparam=spi=on
dtparam=i2c_arm=on
dtoverlay=waveshare35a
and in my cmdline.txt I have this right after rootwait
:
fbcon=map:1 fb con=font:ProFont6x11 logo.nologo
Hi, Let me add my 3 cents 😄 :
I agree with ravenousld3341 - I think the problem lies with Pi0 3,3V bus which can supply ca 50mA... While display need a bit more and white leds draw a one hell of current too (and they are usually connected directly to 3,3V on those displays) - So Pi2 can handle this much current being drawn from it witout issue, but Pi0 have a much smaller DC/DC converter for 3,3V ....
I see now the point behind the current-problem. I'll try to power the display from a separate supply, maybe that will solve the problem.
I'll keep this issue updated after the experiment.
I know this is a bit stretched, but check soldering of pinheader on your Pi0 - maybe there is a bad solder on the MOSI/SCK line (or too much solder flux residues - those can be a real PITA)...
If voltages are within error (especially 3,3V), then current drawn from Pi0 shouldn't be an issue - the larger current being drawn from dc/dc converter the more voltage will drop. Personally, I'd see a problem if 3,3V line would drop to less than 3,25V - but that's me, I'm just a really pedantic 😄 about power lines (and their stability) in my circuits (I put on my PCBs a lot of decoupling capacitors around power pins of chips 😁 - so I actually never had any real problems with power in my designs).
Other than those, I don't have other ideas... This is original waveshare display or clone (and where u get it) maybe I'll order one myself and test it 😃
🥔 🥔 - sorry couldn't resist 😀
it's an original rev4.0 waveshare display, and actually it was a soldering issue, more precisely the lack of my soldering skills :D after rechecking (and in some cases resoldering) the pins everything works fine. thanks for all the help!
Hi,
I was wondering, is it possible to use the waveshare 3.5" (A) display with a pi zero? I tried multiple things, including the dtoverlay from swkim01/waveshare-dtoverlays (which worked flawlessly with the same display on a raspberry pi 2), and some methods from this issue. The result was always the same, blank white screen. Am I missing something, or it is just not possible to use the display with a pi zero?
Thanks, potato