Problems with DS1302 trickle circuit
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Posts: 46,084
Hi guys,
was hoping someone could help me out with a problem i am having
connecting a 1Farad supercap for the backup of my DS1302 RTC.
I have connected everything up and am running the demo program from
the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin Date:
5/18/98). I have built my own developemnt board with an 800mA 5V
regulator onboard.
Everything works fine without any backup. When I connect a 3V disc
type battery between the 0V (gnd) and the Vcc2 pin of the DS1302 it
all works fine and I can happily disconnect the power and the clock
keeps runing.
I then disconnected the battery and connected the 1Farad supercap. It
is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
+5V. I have checked the diode is connected correctly.
When I try to run the program it has a date of 1/1/00 and a time of
00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
This time does not change does not change even though the PC debug
screen indicates there is data being received.
It seems to lock the BS2 up as when I try to reload the program it
hangs or has no effect. I have to turn everything off and disconnect
the supercap and leave it turned off for 30 mins or so before I can
get the program running again. But if I connect the supercap to the
+5V again the program fails.
Any ideas?
Thanks
Col
was hoping someone could help me out with a problem i am having
connecting a 1Farad supercap for the backup of my DS1302 RTC.
I have connected everything up and am running the demo program from
the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin Date:
5/18/98). I have built my own developemnt board with an 800mA 5V
regulator onboard.
Everything works fine without any backup. When I connect a 3V disc
type battery between the 0V (gnd) and the Vcc2 pin of the DS1302 it
all works fine and I can happily disconnect the power and the clock
keeps runing.
I then disconnected the battery and connected the 1Farad supercap. It
is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
+5V. I have checked the diode is connected correctly.
When I try to run the program it has a date of 1/1/00 and a time of
00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
This time does not change does not change even though the PC debug
screen indicates there is data being received.
It seems to lock the BS2 up as when I try to reload the program it
hangs or has no effect. I have to turn everything off and disconnect
the supercap and leave it turned off for 30 mins or so before I can
get the program running again. But if I connect the supercap to the
+5V again the program fails.
Any ideas?
Thanks
Col
Comments
I don't know about the 1302 but the 1307 has a voltage limit of 2
volts to 3.5 volts max. You might check the appnote for the 1302 also check
and make sure your 5 volt power supply can handle the instant charge current
of the capacitor, might want to limit the current of the instant charge.
Build a voltage divider to obtain 3.5 volt charge at the capacitor.
Marv
Original Message
From: <aussiecol39@y...>
To: <basicstamps@yahoogroups.com>
Sent: Saturday, November 10, 2001 10:39 PM
Subject: [noparse][[/noparse]basicstamps] Problems with DS1302 trickle circuit
> Hi guys,
>
> was hoping someone could help me out with a problem i am having
> connecting a 1Farad supercap for the backup of my DS1302 RTC.
>
> I have connected everything up and am running the demo program from
> the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin Date:
> 5/18/98). I have built my own developemnt board with an 800mA 5V
> regulator onboard.
>
> Everything works fine without any backup. When I connect a 3V disc
> type battery between the 0V (gnd) and the Vcc2 pin of the DS1302 it
> all works fine and I can happily disconnect the power and the clock
> keeps runing.
>
> I then disconnected the battery and connected the 1Farad supercap. It
> is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
> +5V. I have checked the diode is connected correctly.
>
> When I try to run the program it has a date of 1/1/00 and a time of
> 00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
> This time does not change does not change even though the PC debug
> screen indicates there is data being received.
>
> It seems to lock the BS2 up as when I try to reload the program it
> hangs or has no effect. I have to turn everything off and disconnect
> the supercap and leave it turned off for 30 mins or so before I can
> get the program running again. But if I connect the supercap to the
> +5V again the program fails.
>
> Any ideas?
>
> Thanks
> Col
>
>
> To UNSUBSCRIBE, just send mail to:
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>
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>
>
thanks for such a fast response, you are a life saver :-)
The 1302 can handle up to 5.5 volts, but of course I didn't think
about current.
One 47k resistor later, (was the only one I had on hand) and
voila .... everything working again.
Thanks again.
Cheers Col
--- In basicstamps@y..., "Marv Skinner" <marvskinner@e...> wrote:
> Col:
> I don't know about the 1302 but the 1307 has a voltage
limit of 2
> volts to 3.5 volts max. You might check the appnote for the 1302
also check
> and make sure your 5 volt power supply can handle the instant
charge current
> of the capacitor, might want to limit the current of the instant
charge.
> Build a voltage divider to obtain 3.5 volt charge at the capacitor.
> Marv
>
Original Message
> From: <aussiecol39@y...>
> To: <basicstamps@y...>
> Sent: Saturday, November 10, 2001 10:39 PM
> Subject: [noparse][[/noparse]basicstamps] Problems with DS1302 trickle circuit
>
>
> > Hi guys,
> >
> > was hoping someone could help me out with a problem i am having
> > connecting a 1Farad supercap for the backup of my DS1302 RTC.
> >
> > I have connected everything up and am running the demo program
from
> > the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin
Date:
> > 5/18/98). I have built my own developemnt board with an 800mA 5V
> > regulator onboard.
> >
> > Everything works fine without any backup. When I connect a 3V disc
> > type battery between the 0V (gnd) and the Vcc2 pin of the DS1302
it
> > all works fine and I can happily disconnect the power and the
clock
> > keeps runing.
> >
> > I then disconnected the battery and connected the 1Farad
supercap. It
> > is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
> > +5V. I have checked the diode is connected correctly.
> >
> > When I try to run the program it has a date of 1/1/00 and a time
of
> > 00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
> > This time does not change does not change even though the PC debug
> > screen indicates there is data being received.
> >
> > It seems to lock the BS2 up as when I try to reload the program it
> > hangs or has no effect. I have to turn everything off and
disconnect
> > the supercap and leave it turned off for 30 mins or so before I
can
> > get the program running again. But if I connect the supercap to
the
> > +5V again the program fails.
> >
> > Any ideas?
> >
> > Thanks
> > Col
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
I've seen two differents app notes about the DS1302 on Parallax's website
(or elsewhere...). The good one is "DS1302 Timekeeping Chip.pdf" 162 KBytes
(see DS1302_3.BS2 for the Trickle Charge). The other one, "DS1302 Real-Time
Clock.pdf" 100 KBytes is uncomplete.
You don't need any external component to use the trickle charge function !
You just need to connect the supercap between Vcc1 (pin 8) and ground. The
normal power supply comes on Vcc2 (pin 1).
There are two diodes and three resistors built-in. You can enable one or two
diodes and one of the resistor. The configuration is made by writing a bit
pattern to the DS1302.
I think you'll find the best way to use the DS1302 properly in Application
Note 82 on DALLAS SEMICONDUCTORS's website. It's very complete and useful.
If you can't find it, I can send it to you.
Enjoy,
Phil.
Original Message
From: <aussiecol39@y...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, November 11, 2001 6:39 AM
Subject: [noparse][[/noparse]basicstamps] Problems with DS1302 trickle circuit
> Hi guys,
>
> was hoping someone could help me out with a problem i am having
> connecting a 1Farad supercap for the backup of my DS1302 RTC.
>
> I have connected everything up and am running the demo program from
> the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin Date:
> 5/18/98). I have built my own developemnt board with an 800mA 5V
> regulator onboard.
>
> Everything works fine without any backup. When I connect a 3V disc
> type battery between the 0V (gnd) and the Vcc2 pin of the DS1302 it
> all works fine and I can happily disconnect the power and the clock
> keeps runing.
>
> I then disconnected the battery and connected the 1Farad supercap. It
> is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
> +5V. I have checked the diode is connected correctly.
>
> When I try to run the program it has a date of 1/1/00 and a time of
> 00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
> This time does not change does not change even though the PC debug
> screen indicates there is data being received.
>
> It seems to lock the BS2 up as when I try to reload the program it
> hangs or has no effect. I have to turn everything off and disconnect
> the supercap and leave it turned off for 30 mins or so before I can
> get the program running again. But if I connect the supercap to the
> +5V again the program fails.
>
> Any ideas?
>
> Thanks
> Col
Remember that you have to turn on this feature with a software command. You
have control over how much charging current you want to provide. The Vcc1
and Vcc2 seem backwards to me but they do work as advertised. I have left the
circuit unpowered for about 6 months and the RTC still has kept track of time
and date when I powered it back up again.
George (azeasi)
connected backwards (wrong polarity) or shorted! The markings on the
supercaps are somewhat confusing. I have used several different supercaps and
all work fine.
george (azeasi)
thanks for the advice. i checked the Parallax site and found the
better app note. Also found AN82 on the Dallas site. it explains it
all. Now it makes sense :-)
Haven't had a chance to rip the extra bits out and try, but I am sure
it will be the answer.
Cheers, and thanks again.
--- In basicstamps@y..., "Philippe Derenne" <derennep@s...> wrote:
> Hi Col,
>
> I've seen two differents app notes about the DS1302 on Parallax's
website
> (or elsewhere...). The good one is "DS1302 Timekeeping Chip.pdf"
162 KBytes
> (see DS1302_3.BS2 for the Trickle Charge). The other one, "DS1302
Real-Time
> Clock.pdf" 100 KBytes is uncomplete.
>
> You don't need any external component to use the trickle charge
function !
> You just need to connect the supercap between Vcc1 (pin 8) and
ground. The
> normal power supply comes on Vcc2 (pin 1).
> There are two diodes and three resistors built-in. You can enable
one or two
> diodes and one of the resistor. The configuration is made by
writing a bit
> pattern to the DS1302.
>
> I think you'll find the best way to use the DS1302 properly in
Application
> Note 82 on DALLAS SEMICONDUCTORS's website. It's very complete and
useful.
> If you can't find it, I can send it to you.
>
> Enjoy,
>
> Phil.
>
>
>
Original Message
> From: <aussiecol39@y...>
> To: <basicstamps@y...>
> Sent: Sunday, November 11, 2001 6:39 AM
> Subject: [noparse][[/noparse]basicstamps] Problems with DS1302 trickle circuit
>
>
> > Hi guys,
> >
> > was hoping someone could help me out with a problem i am having
> > connecting a 1Farad supercap for the backup of my DS1302 RTC.
> >
> > I have connected everything up and am running the demo program
from
> > the application kit (Title: DS1302_1.BS2 Author: Jeff A Martin
Date:
> > 5/18/98). I have built my own developemnt board with an 800mA 5V
> > regulator onboard.
> >
> > Everything works fine without any backup. When I connect a 3V disc
> > type battery between the 0V (gnd) and the Vcc2 pin of the DS1302
it
> > all works fine and I can happily disconnect the power and the
clock
> > keeps runing.
> >
> > I then disconnected the battery and connected the 1Farad
supercap. It
> > is connected to 0V and Vcc2 with an IN4007 diode between Vcc2 and
> > +5V. I have checked the diode is connected correctly.
> >
> > When I try to run the program it has a date of 1/1/00 and a time
of
> > 00:00:80 (even though the program sets the date to 3:00pm 5/18/98)
> > This time does not change does not change even though the PC debug
> > screen indicates there is data being received.
> >
> > It seems to lock the BS2 up as when I try to reload the program it
> > hangs or has no effect. I have to turn everything off and
disconnect
> > the supercap and leave it turned off for 30 mins or so before I
can
> > get the program running again. But if I connect the supercap to
the
> > +5V again the program fails.
> >
> > Any ideas?
> >
> > Thanks
> > Col
Thanks for the advice. The app note I had suggested I needed an
external diode - and who am I to question an App Note :-)
Thanks to everyones help I now have it sorted, with no external
components.
Cheers
Col
--- In basicstamps@y..., azeasi@a... wrote:
> Why the 1n4007 diode? You don't need it! Sounds like your supercap
is
> connected backwards (wrong polarity) or shorted! The markings on
the
> supercaps are somewhat confusing. I have used several different
supercaps and
> all work fine.
> george (azeasi)