stuck on stamps...also power management
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Posts: 46,084
Actually Mosfets are available in the milliohm range, some of us use wire
that has as much resistance.
Another thought is using a regulator that has a shutdown feature...
KF4HAZ - Lonnie
Original Message
From: "Chris Loiacono (E-mail)" <chris01@
> As a stamp loyalist, I find myself working on a never-ending hobby project
> that I have discussed a bit here in the past, yet I find myself searching
> for some new ideas on power management..
>
> I was intending to use the BS2 for a proto only, but every time I look at
> porting this over to a classic controller, the stamp has a few things in
> it's favor.....hence, I'm still with it.
>
> I have an LM34 and a Motorola MPX5700 sensing temp and pressure, each
> outputting to the stamp via ADC0831's. The stamp output at this time is a
> serial LCD, which is about to be replaced, due to it's huge size.
>
> The LCD is not much of a power hog, but the sensor inputs seem to be. I
have
> a routine running that puts the stamp into SLEEP when the MPX does not
> exceed a certain compensated value. The stamp wakes and checks the temp
for
> a correction value, then the MPX and either goes back to sleep or wakes
and
> begins work. If at any time the MPX senses pressure below the compensated
> threshold, it (the stamp) waits a short period, validates the check and
> again, either goes to sleep or continues working.
>
> In search of greater battery life, I am hoping to power down the ADC's and
> sensors during the stamp's sleep time. This is where I am looking for
> ideas - because since relays are obviously not a good choice (size &
> consumption) MOSFet's will have resistance that will upset my ADC apple
> carts...and, besides, I can't keep an output powered while in sleep. Other
> ideas include using devices on the front end that are more power
> conscious...
>
> Has anyone ever bothered to derive a similar power scheme for a stamp
> project like this???
>
> TIA,
> Chris
that has as much resistance.
Another thought is using a regulator that has a shutdown feature...
KF4HAZ - Lonnie
Original Message
From: "Chris Loiacono (E-mail)" <chris01@
> As a stamp loyalist, I find myself working on a never-ending hobby project
> that I have discussed a bit here in the past, yet I find myself searching
> for some new ideas on power management..
>
> I was intending to use the BS2 for a proto only, but every time I look at
> porting this over to a classic controller, the stamp has a few things in
> it's favor.....hence, I'm still with it.
>
> I have an LM34 and a Motorola MPX5700 sensing temp and pressure, each
> outputting to the stamp via ADC0831's. The stamp output at this time is a
> serial LCD, which is about to be replaced, due to it's huge size.
>
> The LCD is not much of a power hog, but the sensor inputs seem to be. I
have
> a routine running that puts the stamp into SLEEP when the MPX does not
> exceed a certain compensated value. The stamp wakes and checks the temp
for
> a correction value, then the MPX and either goes back to sleep or wakes
and
> begins work. If at any time the MPX senses pressure below the compensated
> threshold, it (the stamp) waits a short period, validates the check and
> again, either goes to sleep or continues working.
>
> In search of greater battery life, I am hoping to power down the ADC's and
> sensors during the stamp's sleep time. This is where I am looking for
> ideas - because since relays are obviously not a good choice (size &
> consumption) MOSFet's will have resistance that will upset my ADC apple
> carts...and, besides, I can't keep an output powered while in sleep. Other
> ideas include using devices on the front end that are more power
> conscious...
>
> Has anyone ever bothered to derive a similar power scheme for a stamp
> project like this???
>
> TIA,
> Chris
Comments
Mosfets are pretty good as switches when driven hard. You will find probably
only .5v drop at most.
Alternatively you could use a low power relay which is normally *not
connected* and so only makes the connection when the stamp wants to check
the results.
However one caveat with all this - do the sensors require come sort of
warm-up time once turned on?
Ragrds,
Tony
Original Message
From: "Chris Loiacono (E-mail)" <chris01@t...>
To: "Basicstamps Group (E-mail)" <basicstamps@yahoogroups.com>
Sent: Tuesday, January 29, 2002 7:01 PM
Subject: [noparse][[/noparse]basicstamps] stuck on stamps...also power management
> As a stamp loyalist, I find myself working on a never-ending hobby project
> that I have discussed a bit here in the past, yet I find myself searching
> for some new ideas on power management..
>
> I was intending to use the BS2 for a proto only, but every time I look at
> porting this over to a classic controller, the stamp has a few things in
> it's favor.....hence, I'm still with it.
>
> I have an LM34 and a Motorola MPX5700 sensing temp and pressure, each
> outputting to the stamp via ADC0831's. The stamp output at this time is a
> serial LCD, which is about to be replaced, due to it's huge size.
>
> The LCD is not much of a power hog, but the sensor inputs seem to be. I
have
> a routine running that puts the stamp into SLEEP when the MPX does not
> exceed a certain compensated value. The stamp wakes and checks the temp
for
> a correction value, then the MPX and either goes back to sleep or wakes
and
> begins work. If at any time the MPX senses pressure below the compensated
> threshold, it (the stamp) waits a short period, validates the check and
> again, either goes to sleep or continues working.
>
> In search of greater battery life, I am hoping to power down the ADC's and
> sensors during the stamp's sleep time. This is where I am looking for
> ideas - because since relays are obviously not a good choice (size &
> consumption) MOSFet's will have resistance that will upset my ADC apple
> carts...and, besides, I can't keep an output powered while in sleep. Other
> ideas include using devices on the front end that are more power
> conscious...
>
> Has anyone ever bothered to derive a similar power scheme for a stamp
> project like this???
>
> TIA,
> Chris
>
>
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>
The LT1121 voltage regulator in the 8 pin package has a shutdown pin.
The BS2 can bring bring that pin low to turn off the power to your
sensors. The '1121 draws less than 30 microamps when shut down. Are
you using this both to power your front end and also as a reference
for the ADC?
The LT1121 is not the only option--lots of micropower regulators are
available with a shutdown pin.
A capacitor or pulloff resistor is necessary on the shutdown pin
connection to the BS2, to keep the regulator solidly off during the
glitches that occur every 2.3 seconds during SLEEP.
If you need a zero-power solution, it is usually possible to work
something out with mosfets and a separate reference regulator. I
like the LP0701 p-mosfet from Supertex. It has a very low Vgs
threshold of 1 volt.
-- regards,
Tracy Allen
electronically monitored ecosystems
mailto:tracy@e...
http://www.emesystems.com
>As a stamp loyalist, I find myself working on a never-ending hobby project
>that I have discussed a bit here in the past, yet I find myself searching
>for some new ideas on power management..
>
>I was intending to use the BS2 for a proto only, but every time I look at
>porting this over to a classic controller, the stamp has a few things in
>it's favor.....hence, I'm still with it.
>
>I have an LM34 and a Motorola MPX5700 sensing temp and pressure, each
>outputting to the stamp via ADC0831's. The stamp output at this time is a
>serial LCD, which is about to be replaced, due to it's huge size.
>
>The LCD is not much of a power hog, but the sensor inputs seem to be. I have
>a routine running that puts the stamp into SLEEP when the MPX does not
>exceed a certain compensated value. The stamp wakes and checks the temp for
>a correction value, then the MPX and either goes back to sleep or wakes and
>begins work. If at any time the MPX senses pressure below the compensated
>threshold, it (the stamp) waits a short period, validates the check and
>again, either goes to sleep or continues working.
>
>In search of greater battery life, I am hoping to power down the ADC's and
>sensors during the stamp's sleep time. This is where I am looking for
>ideas - because since relays are obviously not a good choice (size &
>consumption) MOSFet's will have resistance that will upset my ADC apple
>carts...and, besides, I can't keep an output powered while in sleep. Other
>ideas include using devices on the front end that are more power
>conscious...
>
>Has anyone ever bothered to derive a similar power scheme for a stamp
>project like this???
>
>TIA,
>Chris
that I have discussed a bit here in the past, yet I find myself searching
for some new ideas on power management..
I was intending to use the BS2 for a proto only, but every time I look at
porting this over to a classic controller, the stamp has a few things in
it's favor.....hence, I'm still with it.
I have an LM34 and a Motorola MPX5700 sensing temp and pressure, each
outputting to the stamp via ADC0831's. The stamp output at this time is a
serial LCD, which is about to be replaced, due to it's huge size.
The LCD is not much of a power hog, but the sensor inputs seem to be. I have
a routine running that puts the stamp into SLEEP when the MPX does not
exceed a certain compensated value. The stamp wakes and checks the temp for
a correction value, then the MPX and either goes back to sleep or wakes and
begins work. If at any time the MPX senses pressure below the compensated
threshold, it (the stamp) waits a short period, validates the check and
again, either goes to sleep or continues working.
In search of greater battery life, I am hoping to power down the ADC's and
sensors during the stamp's sleep time. This is where I am looking for
ideas - because since relays are obviously not a good choice (size &
consumption) MOSFet's will have resistance that will upset my ADC apple
carts...and, besides, I can't keep an output powered while in sleep. Other
ideas include using devices on the front end that are more power
conscious...
Has anyone ever bothered to derive a similar power scheme for a stamp
project like this???
TIA,
Chris
Original Message
From: Chris Loiacono [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=amRdtdMKIE1q4iILILI_9x4XqUExMcA4lya8yzQfdL18OUqFuqHrx-zRElsREp_DOtk-DFh0iC__1Tg]chris@m...[/url
Sent: Tuesday, January 29, 2002 2:44 PM
To: 'basicstamps@yahoogroups.com'
Subject: RE: [noparse][[/noparse]basicstamps] stuck on stamps...also power management
Thanks Tracy & Tony. I am digging for data sheets and ap notes now.
For the time being, yes, one supply for all. Next phase will go to split 3V
supply, one for PIC, the other for off controller peripherals.
Perhaps one day I'll get to try the Motorola low-power solution. I'm already
impress with how much the Stamp will do - I don't believe I have ever worked
one so hard - I should have mentioned that this one also manages the DS1302
RTC, doing all the sensor and display updates between RTC read cycles. I am
hoping to add some simple data aquisition and an IR LED to transmit the data
to a VB ap. I'm fairly certain that I'm going to bump into time limitations
soon. Your data on execution time is helpful here, Tracy.
And, yes the sensors, as usual need a little time to settle before expecting
reliable data. I guess I'm just having too good of a time seeing just how
far the stamp will go. (although I think Michel takes the prize in this
area!)
I will post back with results....
Thanks,
Chris
Hi Chris,
The LT1121 voltage regulator in the 8 pin package has a shutdown pin.
The BS2 can bring bring that pin low to turn off the power to your
sensors. The '1121 draws less than 30 microamps when shut down. Are
you using this both to power your front end and also as a reference
for the ADC?
The LT1121 is not the only option--lots of micropower regulators are
available with a shutdown pin.
A capacitor or pulloff resistor is necessary on the shutdown pin
connection to the BS2, to keep the regulator solidly off during the
glitches that occur every 2.3 seconds during SLEEP.
If you need a zero-power solution, it is usually possible to work
something out with mosfets and a separate reference regulator. I
like the LP0701 p-mosfet from Supertex. It has a very low Vgs
threshold of 1 volt.
>As a stamp loyalist, I find myself working on a never-ending hobby project
>that I have discussed a bit here in the past, yet I find myself searching
>for some new ideas on power management..
>
>In search of greater battery life, I am hoping to power down the ADC's and
>sensors during the stamp's sleep time. This is where I am looking for
>ideas - because since relays are obviously not a good choice (size &
>consumption)
Latching relays! small, low power, remember their last state without
power. Many people make them - check Omron.
dwayne
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
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Do NOT send unsolicited commercial email to this email address.
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(sometimes I wonder who "they" really are...)
Chris
--
Latching relays! small, low power, remember their last state without
power. Many people make them - check Omron.
dwayne
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
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