Dave,
Thanks A lot, I'll test the next week and i'll comment here the
result.
--- In l..., "derbaier" wrote: >
> --- In l..., "rod_linares" wrote:
> >
> > Tom, im using an DS1390. Is it possible to drive directly the pin
> > RTCX1 with 32khz square wave (3.3v amp) generated by this IC? or MUST > > reduce the amplitude to 2v aprox?
> >
> >
> >
> The data sheet for the LPC213x provides that information for you in
> the Static Characteristics section for the oscilator pins. The
> minimum voltage allowed is zero volts and the maximum voltage allowed > is 1.8 volts in the data sheet that I have here. You
can achieve that > with a simple 2 resistor voltage divider from your
source. Just be
> careful not to use resistor values so large that the pin capacitance
> further reduces your waveform amplitude.
>
> -- Dave
>
--- In l..., "rod_linares" wrote: >
> Tom, im using an DS1390. Is it possible to drive directly the pin
> RTCX1 with 32khz square wave (3.3v amp) generated by this IC? or MUST
> reduce the amplitude to 2v aprox?
> The data sheet for the LPC213x provides that information for you in
the Static Characteristics section for the oscilator pins. The
minimum voltage allowed is zero volts and the maximum voltage allowed
is 1.8 volts in the data sheet that I have here. You can achieve that
with a simple 2 resistor voltage divider from your source. Just be
careful not to use resistor values so large that the pin capacitance
further reduces your waveform amplitude.
-- Dave
Reply by rod_linares●February 7, 20072007-02-07
Tom, im using an DS1390. Is it possible to drive directly the pin
RTCX1 with 32khz square wave (3.3v amp) generated by this IC? or MUST
reduce the amplitude to 2v aprox?
--- In l..., Tom Walsh wrote: >
> begatchev wrote:
>
> > Has anybody tried inputting an external 32.768kHz clock to the RTCX1 > > and RTCX2 oscillator pins of the lpc213X? Is it
possible at all, since > > nothing seems to be mentioned in the documentation
on this subject. > >
> RTCX1 is the input pin, you would want to leave RTCX2 floating (the
> output of the oscillator). It is a common thing to drive the input pin > of a processor clock with an external clock. Just
keep the signal level > down to something reasonable to avoid over voltage on
the RTCX1 pin
> (approx 2V should work fine).
>
> TomW
>
> --
> Tom Walsh - WN3L - Embedded Systems Consultant
> http://openhardware.net,http://cyberiansoftware.com
> "Windows? No thanks, I have work to do..."
> ----------------
>
Reply by Bisser Gatchev●June 27, 20062006-06-27
Thanks Tom, I thought so myself. The idea is to use an external RTC while the
LPC is powered off, then feed the clock to the internal RTC at power up. The
RS5C372A-E from Ricoh can output 32.768kHz on an INT pin.
Tom Walsh wrote: begatchev wrote:
> Has anybody tried inputting an external 32.768kHz
clock to the RTCX1
> and RTCX2 oscillator pins of the lpc213X? Is it possible at all, since
> nothing seems to be mentioned in the documentation on this subject.
> RTCX1 is the input pin, you would want to leave RTCX2 floating (the
output of the oscillator). It is a common thing to drive the input pin
of a processor clock with an external clock. Just keep the signal level
down to something reasonable to avoid over voltage on the RTCX1 pin
(approx 2V should work fine).
---------------------------------
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Reply by Tom Walsh●June 27, 20062006-06-27
begatchev wrote:
> Has anybody tried inputting an external 32.768kHz
clock to the RTCX1
> and RTCX2 oscillator pins of the lpc213X? Is it possible at all, since
> nothing seems to be mentioned in the documentation on this subject.
> RTCX1 is the input pin, you would want to leave RTCX2 floating (the
output of the oscillator). It is a common thing to drive the input pin
of a processor clock with an external clock. Just keep the signal level
down to something reasonable to avoid over voltage on the RTCX1 pin
(approx 2V should work fine).
Has anybody tried inputting an external 32.768kHz clock to the RTCX1
and RTCX2 oscillator pins of the lpc213X? Is it possible at all, since
nothing seems to be mentioned in the documentation on this subject.
