Enjoy!

In Part 1 and Part 2 of this series of posts I outlined the attempts I have made at using U-Boot to control the booting of the pcDuino. Specifically, I have been trying to configure the second stage boot to be from my SD card instead of the on board NAND flash. Unfortunately, the U-Boot implementation as installed does not allow persistent setting of the environment for boot from an alternative interface. And the installed U-Boot does not support the newer boot.scr or uEnv.txt extensions. The newer U-Boot versions available on linux-sunxi are not compatible with the pcDuino. I also tried the fw_printenv and fw_setenv U-Boot tools, but they only work with /dev/mtdX NAND configurations. I was not able to find a ready made solution, so I had to roll my own. Read more…

In Part 1 I described connecting to the pcDuino serial port and accessing the U-Boot subsystem. With this access to the boot environment, the task of booting to a root file system other than the NAND flash looked promising. Read more…

This evening I decided it was time to check out the boot loader and boot command options on the pcDuino. To access the serial port on the J5 debug port I used a Sparkfun FTDI Basic Breakout-3.3v — a simple to use logic level serial to USB interface. With the power off and the FTDI Basic disconnected from the computer, I connected the serial lines and ground.

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One of the things I had noted earlier was that the HDMI output resolution is fixed at 720p (1280×720) and there was no documented way of setting a new resolution. There was a posting in the comments at Sparkfun that a script for setting the resolution was being worked on. Well, I decided to take a look at it myself and see what was required. It is actually quite simple once you have the right tools. With a little research, I had my display running at 1080p (1920×1080). Read more…