BBB CPU clock (was: Re: FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos).

[Jia-Shiun Li]

On Tue, Oct 1, 2013 at 9:12 PM, Paul Mather <paul at gromit.dlib.vt.edu> wrote:
> What 5V adapter are you using?  The one recommended by Adafruit for the BeagleBone Black is a 5V 2A adapter.  The BBB system reference manual states, "A 5VDC supply can be used to provide power to the board. The power supply current depends on how many and what type of add-on boards are connected to the board. For typical use, a 5VDC supply rated at 1A should be sufficient. If heavier use of the expansion headers or USB host port is expected, then a higher current supply will be required."  The BBB Wiki (http://circuitco.com/support/index.php?title=BeagleBoneBlack) lists the power consumption of the BBB itself as 210--460 mA at 5V depending on "activity and processor speed."  I believe if you use capes with the BBB then you need to use the external PSU.
>
> I've personally found the BBB to be a bit flaky when run via the USB OTG connector.  I prefer to run it via a 5V external PSU for stable operation.

I tried several USB chargers originally for gadgets, rated 850~2000mA.
I thought I overrode current limitation and voltage output of PMIC,
but it did not seem to change much, almost like power output not altered at all.

Another thing strange is that the board is said to use DDR3L which
requires 1.35v and TPS75217D, but the board has rev.C which
defaults DCDC1 to 1.5v for DDR3.

Just in case, I suppose the PMIC does not require extra steps to
'commit' changes? Basically what I did under u-boot prompt is like:

U-Boot# i2c mm 24 1
00000001: 3d ? 3f
00000002: 00 ? U-Boot# i2c mm 24 0b
0000000b: 00 ? 72
0000000c: 7f ? U-Boot# i2c mm 24 0f
0000000f: 08 ? 11
00000010: 08 ? U-Boot# i2c mm 24 0b
0000000b: 00 ? 72
0000000c: 7f ? U-Boot# i2c mm 24 0f
0000000f: 08 ? 11
00000010: 08 ? U-Boot# mm 0x44e00488
44e00488: 00000007 ? 4
44e0048c: 00000007 ? U-Boot# mm 0x44e0042c
44e0042c: 00000017 ? 32017
44e00430: 00000000 ? U-Boot# mm 0x44e00488
44e00488: 00000004 ? 7
44e0048c: 00000007 ? U-Boot# boot

Thanks,
Jia-Shiun.