I’m trying to wire up a display from Adafruit (ILI9341) using SPI on the mangOH Red (WP7607, Legato 18.10.3). I already managed to add framebuffer support on the software side, which seems to work fine by itself. I can’t seem to get the display itself working though. It just displays a white screen (instead of going black with backlight on as expected), which shows me that the display is not initialized. When doing something like
cat /dev/urandom > /dev/fb0 I get random black and white flickers, but no real noisy image as expected, so I suspect that SPI works, but it can’t make sense out of the data.
I load the driver in the following way (which gives me a
insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/core/fb_sys_fops.ko insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/core/syscopyarea.ko insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/core/sysfillrect.ko insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/core/sysimgblt.ko insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/fbtft/fbtft.ko insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/fbtft/fbtft_device.ko name=adafruit28 busnum=1 gpios=dc:13 debug=7 insmod /lib/modules/3.18.122/kernel/drivers/video/fbdev/fbtft/fb_ili9341.ko
My wiring looks currently like this (I use the IOT#0 card connector):
- Power (IOT Pin 1, 5V) and GND (IOT Pin 38) is connected to 3-5V and GND on the display.
Since the display seems to power up fine, this seems to be working.
- Connect SPI CLK (IOT Pin 16), MISO (17), MOSI (18) and SS (19) to the equally named display pins.
- I connect the GPIO pin 13 (labeled GPIO_2 / IOT Pin 25 on the IOT card) to the D/C pin of the display. I checked that this pin actually changes its level when changing the value using
I should note that the display is mostly used by Raspberry users and was probably developed for it and I can also confirm that it works on a RaPi. I’m currently suspecting that the logic level of 1.8V on the SPI pins is not high enough for the display and thus just displays white. I guess I could use the RaPi connector on the mangOH which have a level of 3.3V? How would I tell the
fbtft driver to use that? I only have
/sys/class/spi_master. Are there any other differences you guys can think of?
Any ideas appreciated.