BeagleBone & Boot Pins

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1

Hi,
Please tell me about correct circuitry to use boot pins as input,

I use Beaglbone Black and want to use these pins,
especially eQep counter pins P8-33,35,41,42 that match to SYS_BOOT 4,5,12,13.

In SRM (ver A6) p104 it says,
“If you plan to use any of these signals, then on power up, these pins should not be driven.”

Which of below is correct circuitry?
A) Attach pins to ground until SYS_RESETn goes high.
B) Keep pins floated until SYS_RESETn goes high.

A is easier, because it can be done by switching 1 relay pulling all pins to ground.
For B, I need plenty relays.

Thanks,
Tohru

2013年4月12日金曜日 4時20分23秒 UTC+9 DarkHelmet:

2

A. The pins cannot float. They are already terminated on the board, either hi or lo.

Gerald

3

So I should not input high,low either .
I undertood. Thank you.

2013年10月28日月曜日 22時14分01秒 UTC+9 Gerald:

4

Correct. Unless you want to change the boot mode.

Gerald

5

Hi, I want to change the boot order of the beaglebone black to USB disk-> eMMC->others. What topics should I study? I also want to remove the boot button. I want it such that whenever the U-Boot would search in the USB for linux image.

Thanks.

6

My suggestion, and it is just a suggestion, would to read the System Reference Manual.

http://www.elinux.org/Beagleboard:BeagleBoneBlack

Gerald

7

Basically, you need to learn how uboot works, and how to use the uEnv.txt file. I wrote up a blog about booting from USB here: http://www.embeddedhobbyist.com/debian-tips/beaglebone-black/beaglebone-black-usb-boot/

Passed this, uboot has the “boot round robin check” hard coded in. Which I am pretty sure could be changed before recompiling.