LCD and DVI Display Solutions¶
The MitySOM-335x Development Kit can support either LCD output through a dedicated header (J401) or DVI video data that is transmitted through the HDMI video only port (J400). Currently 3 differentdisplay modes are supported and the following table lists the UBoot environment setting that is needed to set the proper output for each type.
- optargs video=da8xx:bpp=16,mode=1280x768
- optargs video=da8xx:bpp=16,mode=800x600 - Note that if the ,mode=800x600 is left out of the parameter that is the default setting.
- optargs video=da8xx:bpp=16,mode=1024x768 - To be verified for LCD and may not be supported in Kernel version shipped with MitySOM-335x Dev Kits currently.
It is possible to add support for many other resolutions and modes. Typically it will take a couple hours the first time through to add a new mode to the kernel. Changing the video mode to support 24-bit color is possible and there is an errata published by TI (http://www.ti.com/lit/er/sprz360b/sprz360b.pdf) that explains how the bit lanes are shuffled for the highest 8-bits.
In order for the DVI/HDMI output to function the TFP410 IC needs to be reset using the following environment variable set from UBoot:
config_dvi=i2c dev 1;i2c mw 38 8 3d; i2c mw 38 33 0
This is usually called from the "bootcmd" parameter by using "run config_dvi;" within the boot parameter line.
LCD Header (J401)¶
Currently Critical Link offers a display kit that features a 6.5" 1024x768 resolution LCD from NEC, NL10276BC13-01, and also a display driver adapter board that is available for the MitySOM-335x development kit. The adapter board connects to J401 and takes the DVI video output signals from the MitySOM-335x System on Module installed in the kit and converts them to the proper signals for the NEC LCD using a SN65LVDS84A. The adapter board also provides the necessary back-light driver circuits through the use of six (6) TI TPS61165DBVR drivers.
Touch screen support on the adapter board is currently through a A2D interface. As shown in the schematic a SPI interface is available but currently the parts are NOT populated on the driver board for that feature.
Attached to this Wiki page is the current version of the schematics for the driver board.