comp.arch.embedded Google Group

Re: Time

2009-11-08T17:16:50Z

POSIX *used* to allow for *double* leap seconds. I think
that capability has been removed.
Note that leap seconds can also *subtract* a second (though
this has never? happened)
*All* "human formatted" time schemes are PITAs for machines.
The only realistic way to track time is just to count seconds.

Re: mmap returning MAP_FAILED

2009-11-08T17:09:56Z

That would do terrible things to the utility of shared memory -- no,
MAP_SHARED and PROT_WRITE are compatible. Maybe you're thinking of
MAP_SHARED and MAP_ANONYMOUS (which didn't used to be compatible, but is
since 2.4).

Need help from programming masters (USB hub)

2009-11-08T17:07:46Z

Hi guys!
I am just wondering if you could give some codes regarding the operation of
the USB hub. Since a USB host is capable of communicating to a single
device, I was thinking of using the USB hub as the device. The
communication is from HOST to HUB. However, I need a piece of code to
communicate to the hub to enumerate it and learn about physical bus events

Re: Use of MAX232 as power supply for operational amplifier in 5V powered system?

2009-11-08T16:59:46Z

I like it because it is dirt cheap. Last time I needed fairly
small quantities of an RS232 driver the ST232 was 70-odd pence a
peice. The MAX232 was around four or five times that as I remember.
That's a big premium simply for the brand name genuine part.

Re: Time

2009-11-08T17:05:28Z

My point is that by *defining* system time to be a monotonically
increasing, unresetable function, you *can* make this assumption
for "system times". I.e., if you look at the system time
at any arbitrary time, T1, and then look at it at *any*
arbitrary time thereafter, T2, you *know* that T2 > T1.
By definition. :>

Re: Time

2009-11-08T16:39:05Z

Many, many bugs have been caused by this kind of assumption.
Perhaps the most notable example is the lbolt variable inside
traditionally structured Unix kernels. I'm most familiar with it
from dealing with SCO Unix in the past but ISTR it affected other
systems too, mostly with third party drivers where the develpers

Re: Time

2009-11-08T16:35:04Z

On Sun, 08 Nov 2009 08:27:02 +0000, Paul E Bennett
The UTC is not a linear time scale due to the leap seconds that are
added at random intervals (3, 6, 9, 12, 15 .. month) due to the
slowing down of the rotation of the Earth. When the leap second is
added, the clock should count 23:59:59, 23:59:60, 00:00:00 ....

Re: Software real time clock using timer unit

2009-11-08T16:25:38Z

On Sun, 08 Nov 2009 09:35:23 -0600, "alex99" <alex.xande...@gmail.com>
wrote:
Decide on a useful interval. For a human-space display, a 1 Hz update is
plenty. Then, given your device's clock, PLL setting, and peripheral
clock divider, select a prescaler and match register pair that results
in a 1 Hz event. Set the timer's control registers appropriately and,

Re: Time

2009-11-08T16:22:55Z

The process tells the system that it should be notified about the time
changes. So, even if the process is not running, the system could
activate it.
Where is a problem? There are many "relative" and "absolute" qualities
besides time. You deal with relative or absolute time just like you deal
with relative or absolute path, so to speak.

IWC Classic Pilot Automatic Chronograph Mens Watch IW371712

2009-11-08T16:20:26Z

IWC Classic Pilot Automatic Chronograph Mens Watch IW371712
Wholesale Price : $170.00
Retail Price : $198.00
Click here to get more info :
[link]
.............................. ............................

Re: Software real time clock using timer unit

2009-11-08T16:16:38Z

It would help if you told which ARM controller you're using.

Why do I get the this error - "Read from unprogrammed EEPROM address"

2009-11-08T16:02:56Z

Mu Code for HC12 is given below :
USER_STACKTOP equ $0a00 ;just above RAM area
PORTA equ $0000 ;Port A register
PORTB equ $0001 ;Port B register
PORTP equ $0056 ;Port P register
DDRA equ $0002 ;Port A Data Direction Register
DDRB equ $0003 ;Port B Data Direction Register
DDRP equ $0057 ;Port P Data Direction Register

Re: What coding standard are you using for C?

2009-11-08T15:46:41Z

<grin> Or folks who used "VCR data recorders" manufactured
iin somebody's garage...
*This* is the key issue here! 20 years ago I spent several weeks
takiing everything that I had archived (floppies of various
sizes, 9 track tape, a slew of other oddball tapes, etc.) and
copied it onto "modern media". Since then, every project

Software real time clock using timer unit

2009-11-08T15:35:23Z

I am trying to implement a software real-time clock on ARM using
the timer module.
I am pretty much unable to do it at this point and was hoping that someone
could point me in the right direction -- perhaps even coded examples that
could serve as a way to better understand it. I C language but am a newbie

Re: What coding standard are you using for C?

2009-11-08T15:28:13Z

[%X]
[%X]
Wonder how many remember as far back as the Kansas City Tape Standard for
Data Recording onto Audio Cassettes. If really pressed I could still cobble
one of those up. However, if it was really important data to keep, then it
should have been subject to a migration policy so that it was appropriately