DM355 Display driver

Martin said:

I am trying to add Support for an OLED display to the existing display driver in dm355. Unfortunately my hardware configuration makes it impossible to enter the RGB mode in the display, so that it can be written via Hsync, Vsync an Pclk. But I want to use the OSD module of the dm355 processor.

I am not sure I understand the statement above; is it impossible because your hardware design did not connect hsync, vsync, ... signals correctly to support RGB output, or is it simply that you do not have the software to configure the hardware for RGB mode available yet.

Martin said:

My question is: Is it somehow possible to get the Frame data after the OSD so that i can write it on the display. I am planning to toggle some pins to do that. Can you please tell me where I can read the data and how I can read it. Thank you very much.

Unfortunately, after OSD, data goes to video output port and does not have path back to DDR2.  However, if you can help me understand your scenerio, perhaps we can offer other advice.  The DM355 device does support RGB output to digital displays.

Dear Juan,

thank you for your answer. I have an OLED Display with Samsung S6E63D6 controller. It offers different modes how you can initialize it. You can initialize it via SPI or via the parallel interface.

I have to initialize it via the parallel interface because on my hardware the SPI bus is not connected to the display. That works so far, but only when I use the display in the mode with internal clocks. When I try to enter mode with external clocks (called RGB mode in the display datasheet) it doesn't work. That's because I asked to read the data after OSD. My idea was that I get the data after OSD and write it manually to the display without using the display interface.

Is there any possibility to get the display data?

Thank you for your help!

Martin

mmm, so even if your LCD requires internal clocks (I assume this means it wants to be the master) as opposed to external clocks (meaning is the slave and gets fed an external clock), DM355 is very flexible and can either act as a master or slave. 

unfortunately, as I suggested in my previous post, data goes from OSD to display port (no path back to DDR memory), if you had another DM355 connected you can receive data via 2nd DM355 which would write it to DDR2, but this is probrably not an ideal solution.  I thiank we should investigate what signals your OLED display takes and see if we can reconfigure DM355 to meet those requirements.

Dear Juan,

thanks for you effort. After consulting with someone it was possible to change my hardware. Now I can write my display registers via SPI and enter the desired mode with HSync, VSync and PClk.

Now I have to configure the VENC. My display has a resolution of 320x240 pixels and a want to write it in SRGB mode (R, G and B are output serially). It would be really nice if you could give me some assistance with that. The VPBE has so many registers to take care! :-(

I started in modifying the init sequence of davinci_enc_set_prgb in davinci_platform.c but it didn't work. Is there a HowTo where I can go through?

Thanks very much.

Martin

Initially you could probably get a basic serial RGB output by just setting the VDMD field of the VMOD register to 0x3 along with the existing RGB settings, however I have not seen an implementation with a serial RGB display and I do not know of a good walk through for setting one up. Table 82 of SPRUF72c may be of some help, as it at least gives you the register fields you have to work with for SRGB mode, even if you have to determine the actual values for your display.