I need to understand more before I could comment.
I've implemented an ePaper driver under nxgl, but as some of you are
probably aware there needs to be an explicit redraw request to update
an ePaper display.
What is the interface to the ePaper device? Is it through a serial
interface? Or a framebuffer interface?
I'm not quite sure how to do that under nxgl as normally it would be
driven automatically. It also takes a fair bit of time (~14 seconds
for a colour display) during which period access to the ePaper is
'locked out' so the application really does need to be aware of what
is going on.
What do you might by NXGL? It is library of simply drawing helpers. I
take it you are not using NX, the full graphics system. It would update
automatically and we would not be having this discussion.
Since you are redrawing something that was not drawn by NX, it must be
something that you drew in your application? True? Are you using a
software framebuffer?
The correct way to implement a software framebuffer driver for a serial
graphics device is via drivers/lcd/lcd_framebuffer.c. That driver will
allocate the software framebuffer and export a standard NuttX
framebuffer driver interface. The framebuffer driver at
drivers/video/fb.c will expose the framebuffer driver to the
application. From the framebuffer driver you can use the FIOC_MMAP
IOCTL command to get the address of the framebuffer. You would need
enable CONFIG_LCD_UPDATE, then you can use FBIO_UPDATE command to force
the software software framebuffer to be written to the serial hardware.
Here are some examples:
$ find boards -name defconfig | xargs grep CONFIG_LCD_FRAMEBUFFER
boards/arm/stm32/stm3240g-eval/configs/fb/defconfig:CONFIG_LCD_FRAMEBUFFER=y
boards/arm/stm32/stm32f4discovery/configs/max7219/defconfig:CONFIG_LCD_FRAMEBUFFER=y
boards/arm/stm32l4/nucleo-l476rg/configs/nxdemo/defconfig:CONFIG_LCD_FRAMEBUFFER=y
My intention is to add an nx_updatedisplay() API...but is there a
better, or already available, way to do this? It could be done via a
call to nx_setvisibility on the background window I guess, but
personally I don't like overlaid semantics like that...
Now, that sounds like you are using NX. NX will automatically update
the display.
I cannot imagine a situation where that would be necessary. Let's talk
more before you waste your time. I would have to understand what you
are really doing to be able to help you.
Greg
