Re: [beagleboard] BeagleBone & Boot Pins

[Gerald Coley]

These pins are read when coming out of reset to set the boot mode. After that they can be used for all of the other functions, such as LCD or GPIO, as indicated in the System Reference Manual and the processor datasheet.

Gerald

On Fri, Apr 5, 2013 at 5:04 AM, <micka...@gmail.com> wrote:

Hi,

I've a beaglebone with the XAM3359Z0Z,

I discovered that there is 19 pins dedicated to the boot configuration.

The documentation said that depending of the position of the switch, The beaglebone will boot with the sd card, uart, ..... .

( http://processors.wiki.ti.com/index.php/AM335X_StarterWare_Booting_And_Flashing#Boot_Modes)

I wanted to know if it is possible to use these pins for an another usage? How ? I don't need an another boot mode, the default one is enough for me.

Thank you in advance for your help,

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Gerald

 

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[tohr...@gmail.com]

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:

You can absolutely use them for other usages, once the value has been latched at boot they can be re purposed  It may be necessary to strengthen the pull up/down on those lines with external resistors though. I've encountered an issue where my TTL inputs were pulling the lines low at boot while the CPU latched the config, preventing it to boot from the correct configuration. Resistors of ~50k seem to do the trick.

[Gerald Coley]

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

Gerald

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[tohr...@gmail.com]

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:

[Gerald Coley]

Correct. Unless you want to change the boot mode.

Gerald

[engka...@gmail.com]

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.

[Gerald Coley]

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

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

Gerald

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[William Hermans]

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.