----Original Message----
From: l...
[mailto:l...] On Behalf Of Wagner Loebel
(GMAIL) Sent: 06 October 2009 17:26 To:
l... Subject: Re: [lpc2000] Re: RTC
doubt with LPC2368
> Really, the only way to get RTC working on reset
or
> without power supply is selecting external crystal.
>
> But with this option there's no accuracy. I adjust the
> RTC few days ago and since then I'm wathing RTC
> forwarding 1 sec a day. After a long period the RTC time
> will be wrong !
>
> The LPC17xx have an auto calibration feature, very nice !
> http://www.nxp.com/acrobat_download/applicationnotes/AN10849_1.pdf
>
> But LPC2368 I'll need to create my own auto-calibrate
> function, by stopping the counter a right and little
> calculated ticks to maintain the correct time.
>
> Is this the right way ? Has anyone a better suggestion ?
>
We've done a couple of applications with LPC2478 RTC and it has been
much more accurate than that. Are the loading caps on the 32Khz crystal
correct, this can change the frequency.
Reply by Michael Freeman●October 6, 20092009-10-06
If you need better accuracy you need to use a external TCXO, and you may
need voltage divider on its output. I cannot remember if the 32K osc pins
are at core voltage or not, you will have to look this up. There is a wide
range of TCXOs for you to choose from, some will give you 30 seconds a year
loss.
Michael Freeman
Update Systems Inc.
-----Original Message-----
From: l... [mailto:l...]On Behalf Of
Wagner Loebel (GMAIL)
Sent: Tuesday, October 06, 2009 11:26 AM
To: l...
Subject: Re: [lpc2000] Re: RTC doubt with LPC2368
Really, the only way to get RTC working on reset or without power supply
is selecting external crystal.
But with this option there's no accuracy. I adjust the RTC few days
ago
and since then I'm wathing RTC forwarding 1 sec a day. After a long
period
the RTC time will be wrong !
But LPC2368 I'll need to create my own auto-calibrate function, by
stopping the counter a right and little calculated ticks to maintain the
correct time.
Is this the right way ? Has anyone a better suggestion ?
Thanks
Wagner Loebel
----- Original Message -----
From: Tim Mitchell
To: l...
Sent: Monday, October 05, 2009 5:22 AM
Subject: RE: [lpc2000] Re: RTC doubt with LPC2368
I don't think you have selected the 32Khz crystal for the RTC
According to datasheet p566, to set 32Khz crystal you need to set CCR to
0x10 (bit 4)
Reply by "Wagner Loebel (GMAIL)"●October 6, 20092009-10-06
Really, the only way to get RTC working on reset or without power supply is
selecting external crystal.
But with this option there's no accuracy. I adjust the RTC few days ago and
since then I'm wathing RTC forwarding 1 sec a day. After a long period the
RTC time will be wrong !
But LPC2368 I'll need to create my own auto-calibrate function, by stopping
the counter a right and little calculated ticks to maintain the correct time.
Is this the right way ? Has anyone a better suggestion ?
Thanks
Wagner Loebel
----- Original Message -----
From: Tim Mitchell
To: l...
Sent: Monday, October 05, 2009 5:22 AM
Subject: RE: [lpc2000] Re: RTC doubt with LPC2368
I don't think you have selected the 32Khz crystal for the RTC
According to datasheet p566, to set 32Khz crystal you need to set CCR to
0x10 (bit 4)
Reply by Felipe de A N L●October 3, 20092009-10-03
Yes. there is two xtal, one for the RTC and one for the ARM7.
2009/10/3 gsntone
> Hi Wagner,
>
> "Man, your are doing things WRONG. To solve it, use external clock with a
> 32.768KHz xtal."
>
> With battery and external crystal for RTC your problem should be solved.
> (AFAIK my etteam-board has this 32.768 kHz crystal).
> This option is the only way to keep your RTC running.
>
> Hope this helps,
> Gerd
> --- In l... , "Wagner Loebel
> \(GMAIL\)" wrote:
> >
> > Hi everybody.
> >
> > I'm Wagner, I'm from Brazil. This is my first post here, I'm
starting
> with ARM7 (I bought a board from ETT -Thailand with LPC2368) and I amazed
> with this uC, I always worked with COP8 from National (coding in assembly,
> crazy thing !!!) and recently with Z8Encore, but this ARM7 is impressive !
> >
> > Ok, I run a lot of samples in this board, web server, telnet, USB HID and
> MSD with SD-Card, etc etc. But now Its time to do some serious work...
> >
> > So I ported my codes from Z8Encore, put a LCD 16x2 to work, buzzer, leds
> blinking, bla bla bla. and... RTC. I run it from external clock and
> internal, both OK but I'm watching a strange behavior when running
with
> internal clock. The RTC "stop to walk" during the time I maintain the reset
> switch pressed.
> >
> > Example:
> >
> > 1) RTC is running perfectly and shows 01:43:31 on LCD.
> > 2) Then I press reset switch and continue with reset pressed for about 10
> seconds;
> > 3) When I release the reset switch, the RTC shows the same time
> (01:43:31) and THEN start to "walk" normally.
> >
> > The same happens when I power off the board, even with a battery on Vbat.
> No matter how many seconds, or minutes or hours it was powered off, the RTC
> dont lose the values because it have a small 3V battery on it Vbat pins
but
> the RTC only return to count seconds, minutes and hours when the power is
ON
> and not RESET. I read in the manual the entire chapter about RTC and others
> parts but not found any clue on how to solve it.
> >
> > I guess its happenning 'cause when the device is powered off the
main
> oscilator is not running and there's any pulse of clock to make de RTC
> "walk", even with a backup battery in VBAT, is it right ?
> >
> > Below this is my initialization code. Can anyone give me some idea or
> tell me if there is something wrong or missing with my initialization code.
> Or to tell me: "Man, your are doing things WRONG. To solve it, use external
> clock with a 32.768KHz xtal"
> >
> > Thanks in advance,
> >
> > Wagner Loebel
> >
> >
> > void RTCInit( void )
> > {
> > PCONP = PCONP | 0x200; //set bit PCRTC
> >
> > RTC_AMR = 0;
> > RTC_CIIR = 0;
> > //RTC_CISS = 0;
> > RTC_CCR = 0x01; //0x11 ext.clock ;; 0x01 int.clock
> > RTC_PREINT = PREINT_RTC; //0x0000016D
> > RTC_PREFRAC = PREFRAC_RTC; //0x00001B00
> >
> > // Start RTC counters
> > RTC_CCR |= CCR_CLKEN;
> > RTC_ILR = ILR_RTCCIF;
> > }
> >
> >
> >
> >
> >
>
Reply by gsntone●October 3, 20092009-10-03
Hi Wagner,
"Man, your are doing things WRONG. To solve it, use external clock with a
32.768KHz xtal."
With battery and external crystal for RTC your problem should be solved. (AFAIK
my etteam-board has this 32.768 kHz crystal).
This option is the only way to keep your RTC running.
Hope this helps,
Gerd
--- In l..., "Wagner Loebel \(GMAIL\)" wrote: >
> Hi everybody.
>
> I'm Wagner, I'm from Brazil. This is my first post here,
I'm starting with ARM7 (I bought a board from ETT -Thailand with LPC2368)
and I amazed with this uC, I always worked with COP8 from National (coding in
assembly, crazy thing !!!) and recently with Z8Encore, but this ARM7 is
impressive !
>
> Ok, I run a lot of samples in this board, web server, telnet, USB HID and MSD
with SD-Card, etc etc. But now Its time to do some serious work...
>
> So I ported my codes from Z8Encore, put a LCD 16x2 to work, buzzer, leds
blinking, bla bla bla. and... RTC. I run it from external clock and internal,
both OK but I'm watching a strange behavior when running with internal
clock. The RTC "stop to walk" during the time I maintain the reset switch
pressed.
>
> Example:
>
> 1) RTC is running perfectly and shows 01:43:31 on LCD.
> 2) Then I press reset switch and continue with reset pressed for about 10
seconds;
> 3) When I release the reset switch, the RTC shows the same time (01:43:31) and
THEN start to "walk" normally.
>
> The same happens when I power off the board, even with a battery on Vbat.
No matter how many seconds, or minutes or hours it was powered off, the RTC
dont lose the values because it have a small 3V battery on it Vbat pins but the
RTC only return to count seconds, minutes and hours when the power is ON and not
RESET. I read in the manual the entire chapter about RTC and others parts but
not found any clue on how to solve it.
>
> I guess its happenning 'cause when the device is powered off the main
oscilator is not running and there's any pulse of clock to make de RTC
"walk", even with a backup battery in VBAT, is it right ?
>
> Below this is my initialization code. Can anyone give me some idea or tell
me if there is something wrong or missing with my initialization code. Or to
tell me: "Man, your are doing things WRONG. To solve it, use external clock with
a 32.768KHz xtal"
>
> Thanks in advance,
>
> Wagner Loebel
>
>
> void RTCInit( void )
> {
> PCONP = PCONP | 0x200; //set bit PCRTC
>
> RTC_AMR = 0;
> RTC_CIIR = 0;
> //RTC_CISS = 0;
> RTC_CCR = 0x01; //0x11 ext.clock ;; 0x01 int.clock
> RTC_PREINT = PREINT_RTC; //0x0000016D
> RTC_PREFRAC = PREFRAC_RTC; //0x00001B00
>
> // Start RTC counters
> RTC_CCR |= CCR_CLKEN;
> RTC_ILR = ILR_RTCCIF;
> }
>
>
>
>
>
Reply by "Wagner Loebel (GMAIL)"●October 3, 20092009-10-03
Hi everybody.
I'm Wagner, I'm from Brazil. This is my first post here, I'm
starting with ARM7 (I bought a board from ETT -Thailand with LPC2368) and I
amazed with this uC, I always worked with COP8 from National (coding in
assembly, crazy thing !!!) and recently with Z8Encore, but this ARM7 is
impressive !
Ok, I run a lot of samples in this board, web server, telnet, USB HID and MSD
with SD-Card, etc etc. But now Its time to do some serious work...
So I ported my codes from Z8Encore, put a LCD 16x2 to work, buzzer, leds
blinking, bla bla bla. and... RTC. I run it from external clock and internal,
both OK but I'm watching a strange behavior when running with internal
clock. The RTC "stop to walk" during the time I maintain the reset switch
pressed.
Example:
1) RTC is running perfectly and shows 01:43:31 on LCD.
2) Then I press reset switch and continue with reset pressed for about 10
seconds;
3) When I release the reset switch, the RTC shows the same time (01:43:31) and
THEN start to "walk" normally.
The same happens when I power off the board, even with a battery on Vbat. No
matter how many seconds, or minutes or hours it was powered off, the RTC dont
lose the values because it have a small 3V battery on it Vbat pins but the RTC
only return to count seconds, minutes and hours when the power is ON and not
RESET. I read in the manual the entire chapter about RTC and others parts but
not found any clue on how to solve it.
I guess its happenning 'cause when the device is powered off the main
oscilator is not running and there's any pulse of clock to make de RTC
"walk", even with a backup battery in VBAT, is it right ?
Below this is my initialization code. Can anyone give me some idea or tell
me if there is something wrong or missing with my initialization code. Or to
tell me: "Man, your are doing things WRONG. To solve it, use external clock with
a 32.768KHz xtal"
