Custom i.mx6ul/ull board; no display, ram test strangeness

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Custom i.mx6ul/ull board; no display, ram test strangeness

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dluberger
Contributor V

I made a custom board based on the i.mx6ull evk.  I have successfully performed the RAM stress test, although I have some problems; for some reason, USB_OTG doesn't work. I copied what was done on the evk, but i'm getting the error in windows "unrecognized device". so from here on out, everything is done either by putting the SD card in jump drive or working via console and u-boot.

1.) I was able to run RAM stress test, but for some reason, I can't choose a DDR size bigger than 512 MB, even though my DDR is 4GB. I'm using DDR3L from ISSI part number IS43TR16256AL-125KBLI

2.) I still have a lot of work to do to get the device tree for linux modified for my hardware changes from the evk, but i have a new custom LCD; it's a 5" TFT at 800x480 resolution 24 bit RGB. I currently have just u-boot running on my sd card. How can I test the display without linux? I modified the u-boot code for my board to use the panel name "TFT50" with the correct resolution modified (was set for TFT43AB at 480x272), but right now my screen comes up blank because the LCD is being disabled. is there a way from the u-boot command line to set the backlight gpio to turn on the backlight, and then somehow display something on the screen? i thought there was a default image for the display while in u-boot and not booted into the OS, but like I said the display seems to be stuck off; I'm using GPIO5_IO9 like in the evk to enable/disable the LCD power supplies.  I can't find any documentation on using the u-boot gpio command and i don't know what name to call when using "gpio set" for GPIO5_IO9 to enable the LCD power and GPIO1_IO8 to enable the backlight (also the same as the evk board).

By the way, I'm not using yocto project for any of this because the documentation is so terribly convoluted; so I'm following other guides to manually configure and compile u-boot, the linux kernel, and different distros i'm trying to make work like debian linaro.  Right now i'm just focusing on hardware testing as much as i can through u-boot.

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massimo2
Contributor III

Your ISSI module is 4Gb so 512MB...that is why you cannot chose higher

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igorpadykov
NXP Employee
NXP Employee

Hi David

for ddr test usage one can look at presentation

DES-N1936 i.MX 6UltraLite DDR Tools Overview and Hardware Design Considerations.pdf 

Note i.MX6ULL ddr memory size is limited to 2GB according to Table 2-1. System memory map

i.MX6ULL Reference Manual

http://www.nxp.com/docs/en/reference-manual/IMX6ULLRM.pdf 

For custom LCD it is necessary to adjust timings in struct display_info_t const displays[]

uboot/board/freescale/mx6ullevk/mx6ullevk.c

mx6ullevk.c\mx6ullevk\freescale\board - uboot-imx - i.MX U-Boot 

As help one can use attached Porting Gude and FreeRTOS elcdif examples:

Board Support Packages (3)
SDK2.2_iMX6ULL_WIN(REV SDK2.2)
i.MX 6ULL Applications Processor | Single Arm® Cortex®-A7 @ 900 MHz |NXP 


Best regards
igor
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dluberger
Contributor V

I'm confused. If the RAM limit is 2GB, why does the ULL evk show 4GB and 8GB as memory values? Is that what's just commonly available and the processor simply doesn't address the upper memory space?

I downloaded the SDK but I'm not seeing any documentation on how to use it to configure the boot loader or device tree for my board. how do I use the sdk to get a bootloader, kernel, and desktop on my board?

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