in my long quest (search the forum) to connect a low power display to the Raspberry I am moving from a 3 bit SPI display (which in the end worked) to something more colorful, i.e. an Ortustech Blanview 18 bit (3 x 6 bit) parallel display which I hope to drive via DPI. If you are interested, data sheet is here
What I have done so far is following more or less these docs
https://www.raspberrypi.org/documentati ... /README.md
https://www.raspberrypi.org/forums/view ... ource Labs and I've started checking basic signals, i.e. clock and h/v sync.
As I suspected, nothing appears. They are stable 1 (or 0 depends).. but nothing alternates as was expected.
I've tried driving the pins directly with some python scripts or with the gpio command from WiringPi and I can see signals on the same pins, so the logic analyzer setup seems correct.
I'm connecting to the Raspberry via wifi and Ssh.
So my questions are many, in growing order of basicness
1) Is it correct to try to display an image with sudo fbi -T 1 colorbars.gif and expect it, if the correct overlay is loaded, to make some signal appear on the relevant pins? I don't want an image now, I'd be happy to see some clock.
1.1) would signals appear even if the magic numbers in config.txt are wrong? In some forums someone suggested that the clock must be at least 32K for the raspberry to drive DPI, but then it was contradicted in other messages.
2) I then discovered that dtoverlay -l listed that there was no dpi18 overlay so I've tried loading it at runtime via dtoverlay dpi18
and got this error
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dtoverlay dpi18 * Failed to apply overlay '0_dpi18' (kernel)
HAving done so, should I reasonably expect something to work (signal wise, and using FBI?). Are the other DPI related params in config.txt taken into account? How can I check? using *gpio readall* I see that every pin is in IN mode, and not in ALT2, but I don't know how to change mode apart from enabling the device tree overlayroot@raspberrypi(ro):~# dtoverlay -l
No overlays loaded
root@raspberrypi(ro):~# dtoverlay dpi18
root@raspberrypi(ro):~# dtoverlay -l
Overlays (in load order):
3) regarding this doc here https://www.raspberrypi.org/documentati ... /README.md, many assumptions are made regarding default polarities, pixel clock and enable disable, that may be trivial to most of the HW specialists, but certainly not to me..
what is default for HDMI mode?hsync/vsync/output_enable_polarity:
0: default for HDMI mode
invert with respect to what?<v_sync_polarity> = invert vsync polarity
This is in order to help me get the magic numbers and output format correctly.. but of course I will get there once I've solved steps 1) and 2).
Thanks to any pointer in the right direction.
btw this is my original config.txt
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gpu_mem_256=128 gpu_mem_512=256 gpu_mem_1024=256 overscan_scale=1 dtparam=i2c_arm=off dtparam=spi=off [all] dtoverlay=dpi18 overscan_left=0 overscan_right=0 overscan_top=0 overscan_bottom=0 enable_dpi_lcd=1 display_default_lcd=1 dpi_group=2 dpi_mode=87 framebuffer_width=320 framebuffer_height=240 dpi_timings=240 0 0 1 2 320 0 0 1 2 0 0 0 60 0 4608000 1 dpi_output_format=393237 boot_delay=0