spike at program end
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I ran a simple program on the BS2
LOW 0
END
Then put an LED on the 5 volt power and pin 0
with a 220 ohm resistor.
The LED lit, then after a second, it had a brief
off, then each second or so, I see the LED flash off.
Does anybody have any ideas about this?
If it was a relay, I would need a capacitor to
maintain a value, but it would not be ideal.
Dave
LOW 0
END
Then put an LED on the 5 volt power and pin 0
with a 220 ohm resistor.
The LED lit, then after a second, it had a brief
off, then each second or so, I see the LED flash off.
Does anybody have any ideas about this?
If it was a relay, I would need a capacitor to
maintain a value, but it would not be ideal.
Dave
Comments
End places the BS2 in a low power mode.
Stamp Manual, V1.9, page 260:
"..if the BS2 is driving an LED on when END executes, the LED will stay lit
after END. But every 2.3 seconds, there will be a visible wink of the LED
as the output pin driving it disconnects for 18 ms."
Ray McArthur
Original Message
From: Big Guy <davemucha@j...>
To: <basicstamps@egroups.com>
Sent: Thursday, August 03, 2000 7:20 PM
Subject: [noparse][[/noparse]basicstamps] spike at program end
> I ran a simple program on the BS2
>
> LOW 0
> END
>
> Then put an LED on the 5 volt power and pin 0
> with a 220 ohm resistor.
>
> The LED lit, then after a second, it had a brief
> off, then each second or so, I see the LED flash off.
>
> Does anybody have any ideas about this?
>
> If it was a relay, I would need a capacitor to
> maintain a value, but it would not be ideal.
Stamp goes to sleep after the 'end', the outputs cycle to inputs every 2s
for ~18ms. In other words a low pin will go high momentarily. If you use
'stop' it will not flash. The problem with stop is that it keeps using full
operating current when the program stops, very hard on batteries.
From: "Big Guy" <davemucha@j...>
To: <basicstamps@egroups.com>
Sent: Thursday, August 03, 2000 4:20 PM
Subject: [noparse][[/noparse]basicstamps] spike at program end
> I ran a simple program on the BS2
>
> LOW 0
> END
>
> Then put an LED on the 5 volt power and pin 0
> with a 220 ohm resistor.
>
> The LED lit, then after a second, it had a brief
> off, then each second or so, I see the LED flash off.
>
> Does anybody have any ideas about this?
>
> If it was a relay, I would need a capacitor to
> maintain a value, but it would not be ideal.
>
> Dave
>
>
>
Norm & Monda
Cozy MK IV #202
Ford V-6 Powered
Original Message
From: "Big Guy" <davemucha@j...>
To: <basicstamps@egroups.com>
Sent: Thursday, August 03, 2000 7:20 PM
Subject: [noparse][[/noparse]basicstamps] spike at program end
> I ran a simple program on the BS2
>
> LOW 0
> END
>
> Then put an LED on the 5 volt power and pin 0
> with a 220 ohm resistor.
>
> The LED lit, then after a second, it had a brief
> off, then each second or so, I see the LED flash off.
>
> Does anybody have any ideas about this?
>
> If it was a relay, I would need a capacitor to
> maintain a value, but it would not be ideal.
>
> Dave
>
>
>
Yes, the Stamp wakes up once every 2.3 seconds from the sleep mode, and the
pin becomes an input for 18 milliseconds. How to work around it? As Dave
pointed out, you can use STOP instead of END, if you don't mind continuous
8ma versus 50 or 100 microamps for the sleep mode. Another way is to have
the pin control the load via a mosfet or a cmos gate. A small capacitor on
the gate input holds the charge and keeps the load turned ON or OFF during
the brief hi-Z glitches. You can usually get by even without the
capacitor, because the intrinsic MOS gate capacitor is enough to hold the
state.
|\
P0
o---| >----load
| |/
100pf === cmos gate
| or mosfet
Vss
-- Tracy
Electronically Monitored Ecosystems
http://www.emesystems.com