Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west

Read recently that they'd made mram-based flip flops, which retain
their state when powered off. Can't find them with a quick search,
though.

You could match that with a reset controller chip to get a clean edge
once the system is powered up.

West wrote:
::I would like to have the output change from low to high
:r high to low every time the system is turned on.
::Each power up of the circuit changes or "flips" the output state.
::
DJ Delorie wrote:
Read recently that they'd made mram-based flip flops,
which retain their state when powered off.
Can't find them with a quick search, though.

Freescale
http://www.google.com/search?q=cache...ells-*+Toshiba

This is what came to my mind:
http://groups.google.com/group/sci.e...lay+Matsu****a
(Hats off for those we miss.)

http://www.google.com/search?q=Latching-relay&num=100

West wrote:
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west



Can you use a mechanical device? A motor driven
cam or something like a car door lock solenoid,
with switches & logic to determine direction?

A mechanical setup has the disadvantage of slow
speed/large size, and the advantage of retaining
the last "setting" forever without needing power.

Ed

West wrote:
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

Use a PIC, and save the state in EEPROM if you don't need more than
1,000,000 power cycles.

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

It's probably not the way to go and we will never know if you don't tell
us what you're really trying to do...

On Dec 6, 10:33�pm, "West" wrote:
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west

A mechanically latching relay would work, as would storing the last
state in non-volatile memory, such as EEPROM or FLASH. -mpm

On Fri, 07 Dec 2007 03:33:33 +0000, West wrote:

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the output is a high, then the system is turned off. When the system is
turned back on, the output goes low. Each power up of the circuit
changes or "flips" the output state. I am willing to incorporate CMOS
and a battery back up in the design. Some of the ideas I entertained is
a divide by 2 in front of the toggle, giving me the same state every
other time. However, I'm not sure how to do this practically or if it's
the way to go. Any suggestions out there? All comments welcomed and
thanks.

Why a 555? Did the teacher say so? Because that's not the chip you'd
use here, unless you're looking for a one-shot to generate the toggle
pulse.

You should ask the teacher why he/she wants to use a 555 here, and
report back.

Good Luck!
Rich

On Fri, 07 Dec 2007 03:33:33 GMT, "West" wrote:

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west

You can buy relays that do this (alternating relays), which are used
for load levelling on machinery (among other things). They are big,
use a lot of power, and cost a fair bit of money, and have a limited
life.

If you want to do it at a chip level, the microcontroller suggestion
is a good one, parts cost will be minimal, and only a few parts
required (an external reset circuit may be called for). Lifetime is
somewhat limited, still *far* better than a relay, and can be improved
by additional orders of magnitude by clever programming to load level
erase operations on EEPROM cells. Not difficult to do. The same thing
could be implemented with a battery-backed CMOS FF (eg. 4013), with
more parts. In either case you'd have to reliably detect and debounce
power state changes. Some of that can be done in firmware with a
micro.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

"West" wrote:
I would like to have the output change from low to high
or high to low every time the system is turned on.
Each power up of the circuit changes or "flips" the output state.

Spehro Pefhany wrote:
You can buy relays that do this (alternating relays),
which are used for load levelling on machinery (among other things).

Many other things--with much lower specs.

They are big,

Maybe the magnetic latching relays you have seen are.
The ones I've seen are tiny.
http://www.google.com/search?q=cache...ion+TO.5+pulse

use a lot of power,

A tiny pulse is typical of the ones I've seen.

and cost a fair bit of money,

DJ's MRAM suggestion makes a bistable relay look cheap.

and have a limited life.

Yup.
http://www.google.com/search?q=cache...000,000.cycles

On Fri, 7 Dec 2007 10:31:29 -0800 (PST), JeffM
wrote:

"West" wrote:
I would like to have the output change from low to high
or high to low every time the system is turned on.
Each power up of the circuit changes or "flips" the output state.

Spehro Pefhany wrote:
You can buy relays that do this (alternating relays),
which are used for load levelling on machinery (among other things).

Many other things--with much lower specs.

They are big,

Maybe the magnetic latching relays you have seen are.
The ones I've seen are tiny.
http://www.google.com/search?q=cache...ion+TO.5+pulse

Those are *latching* relays, not *alternating* relays, so they do need
some circuitry to control them. An alternating relay could be used
as-is.

use a lot of power,

A tiny pulse is typical of the ones I've seen.

and cost a fair bit of money,

DJ's MRAM suggestion makes a bistable relay look cheap.

and have a limited life.

Yup.
http://www.google.com/search?q=cache...000,000.cycles

Lots of latching relays. Eg. http://www.msnbc.msn.com/id/22087790/
but there are scores of different ones available. I've used the
two-coil version which has zero steady state dissipation, and thus no
thermal EMF, for switching some very sensitive (uK) cryogenic sensors.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

In article , DJ Delorie says...

Read recently that they'd made mram-based flip flops, which retain
their state when powered off. Can't find them with a quick search,
though.

You could match that with a reset controller chip to get a clean edge
once the system is powered up.

Ramtron does such a product (FRAM obviously)

http://www.ramtron.com/doc/Products/...ver.asp?grp=19

Robert

--
Posted via a free Usenet account from http://www.teranews.com

Robert Adsett writes:
Ramtron does such a product (FRAM obviously)

Yes! That was it. Thanks!

"Robert Adsett" wrote in message
. ..
In article , DJ Delorie says...

Read recently that they'd made mram-based flip flops, which retain
their state when powered off. Can't find them with a quick search,
though.

You could match that with a reset controller chip to get a clean edge
once the system is powered up.

Ramtron does such a product (FRAM obviously)

http://www.ramtron.com/doc/Products/...ver.asp?grp=19


Robert ... could you please check your link. This sounds like it may be just
what I need, but your link doesn't work. Anxious to hear from you. Thanks.

west

Robert

"Robert Adsett" wrote in message
. ..
In article , DJ Delorie says...

Read recently that they'd made mram-based flip flops, which retain
their state when powered off. Can't find them with a quick search,
though.

You could match that with a reset controller chip to get a clean edge
once the system is powered up.

Ramtron does such a product (FRAM obviously)

http://www.ramtron.com/doc/Products/...ver.asp?grp=19

Robert

Never mind Robert, I found the info using part of your link. I immediately
see a problem in that this FRAM is a sofisticated surface mount chip. All I
need is 1 logic level out. Also, I don't have experience in surface mount.
Do you know if this chip comes in a dip 14 or equiv package? Thanks.

west

"ehsjr" wrote in message
news:gA56j.13916$Lg.11052@trndny09...
West wrote:
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the
output is a high, then the system is turned off. When the system is
turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2
in
front of the toggle, giving me the same state every other time. However,
I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west



Can you use a mechanical device? A motor driven
cam or something like a car door lock solenoid,
with switches & logic to determine direction?

A mechanical setup has the disadvantage of slow
speed/large size, and the advantage of retaining
the last "setting" forever without needing power.

I am now studying latching relays. If I go that way I need to find a small
one. The criteria again is : power on gives a logic low; next power on gives
a logic high. IOW shutting the power off does not change states.

west

Ed

"Arlet Ottens" wrote in message
ll.nl...
West wrote:
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the
output is a high, then the system is turned off. When the system is
turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2
in
front of the toggle, giving me the same state every other time. However,
I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

Use a PIC, and save the state in EEPROM if you don't need more than
1,000,000 power cycles.

Hi Arlet, I always wanted to learn about PIC. Perhaps you can recommend a
good beginner's book. I do have some basic electronics experience.

west

"Fred Bloggs" wrote in message
...

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the
output is a high, then the system is turned off. When the system is
turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2
in
front of the toggle, giving me the same state every other time. However,
I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

It's probably not the way to go and we will never know if you don't tell
us what you're really trying to do...

I tried to make my requirements as simple as possible with only a logic
state that toggles with each power on. Why do you require to know what goes
on after that? I don't even know until next semester.

west

"Rich Grise" wrote in message
news:3Lf6j.29$OR.18@trnddc01...
On Fri, 07 Dec 2007 03:33:33 +0000, West wrote:

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the output is a high, then the system is turned off. When the system is
turned back on, the output goes low. Each power up of the circuit
changes or "flips" the output state. I am willing to incorporate CMOS
and a battery back up in the design. Some of the ideas I entertained is
a divide by 2 in front of the toggle, giving me the same state every
other time. However, I'm not sure how to do this practically or if it's
the way to go. Any suggestions out there? All comments welcomed and
thanks.

Why a 555? Did the teacher say so? Because that's not the chip you'd
use here, unless you're looking for a one-shot to generate the toggle
pulse.

You should ask the teacher why he/she wants to use a 555 here, and
report back.

Good Luck!
Rich

You're probably right, Rich because a general purpose F/F may also work.

west

In article 85B6j.3432$3s1.1167@trnddc06, West says...

"Robert Adsett" wrote in message
. ..
In article , DJ Delorie says...

Read recently that they'd made mram-based flip flops, which retain
their state when powered off. Can't find them with a quick search,
though.

You could match that with a reset controller chip to get a clean edge
once the system is powered up.

Ramtron does such a product (FRAM obviously)

http://www.ramtron.com/doc/Products/...ver.asp?grp=19

Never mind Robert, I found the info using part of your link. I immediately
see a problem in that this FRAM is a sofisticated surface mount chip. All I
need is 1 logic level out. Also, I don't have experience in surface mount.
Do you know if this chip comes in a dip 14 or equiv package? Thanks.

If it's not on their site I doubt it, Surface mount isn't hard to work
with though and most newer chips no longer come in DIP packages so it's
worth learning how to deal with them.

Robert

--
Posted via a free Usenet account from http://www.teranews.com

Fred Bloggs wrote:
It's probably not the way to go and we will never know
if you don't tell us what you're really trying to do...

West wrote:
Why do you require to know what goes on after that?
I don't even know until next semester.

Here's the first step of a project:
http://www.google.com/search?q=intit...on+-0471618928
http://groups.google.com/group/sci.e...t+*-*-*-*-*-Hz
....and a text with more specific stuff:
http://groups.google.com/group/sci.e... .*.at.a.time
..
After you have that, this is next:
http://groups.google.com/group/sci.e...-diagram&fwc=1
(MooseFET went completely nuts with this):
http://groups.google.com/group/sci.e...oes-this&fwc=1

If you want more SPECIFIC advice, give more SPECIFIC details.
Starting at the wrong end is never a good idea.

West wrote:

Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW, the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However, I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west


Don't know your application how ever..
they make latching relays..

Get one with a DPDT set of contacts. One pole will be
used to signal the direction to switch a monostable
type circuit composed of 2 transistors with a few
minor components added.
The relay has 2 coils and thus are used as the collector
load side resisters for the monostable circuit.

The set of contacts you'll be using will have a resister
connected to the Center Pole while the outer contacts,
each being connected to the base of a transistor..
The idea is to create a slight offset so that the monostable
will favor a side. Because there is induction involved
here, the circuit will be fully on position before the coil even
starts the create current. So this means when the contacts do open
to change sides, the unloading effect will not alter the operation.

That will retain the last position with out the use
of constant power.
Of course, you didn't specify the working cycle rate you
expect to get. These relays are mechanical so take it from there.

This is an old trick I have used for years for alternating
a state from a single source point for basic stuff.



--
"I'd rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5

"West" wrote in message
news:ha36j.27973$o_6.25883@trnddc08...
Using a 555 or similar type chip, I would like to have the output change
from low to high or high to low every time the system is turned on. IOW,
the
output is a high, then the system is turned off. When the system is turned
back on, the output goes low. Each power up of the circuit changes or
"flips" the output state. I am willing to incorporate CMOS and a battery
back up in the design. Some of the ideas I entertained is a divide by 2 in
front of the toggle, giving me the same state every other time. However,
I'm
not sure how to do this practically or if it's the way to go. Any
suggestions out there? All comments welcomed and thanks.

west

The professor wants a small box (3"X5") with 4 components on the front panel
An on-off power switch to turn off a 5v to 12v power supply. A green LED
located near the switch to indicate power on. On the left side of the box
there will be 2 LEDs, 1 blue and 1 red. When the power if off = no lights.
When the power is turned on the green and blue LEDs will light. The next
power on the green and red LEDs will come on, etc., etc,..
Next semester we will go further with this but for now, that's all I can
say. Still want to help?

west

West wrote:

The professor wants a small box (3"X5")

A 2D box in a 3D world could be difficult. I have to ask my distributor, if
they have some 2D parts.

Next semester we will go further with this but for now, that's all I can
say. Still want to help?

Do you want that we serve up the homework on a plate to you? Which one of
the many suggested solutions doesn't help you?

I would do it with a microcontroller, because there are ones with
integrated power-on-reset and oscillator, like the MSP430F2111 for $2,25,
so you have to write just about 5 lines of assember code to solve this
task. The datasheet says the integrated flash has a life time of 100,000
erase/program cycles, so this should be fine, unless your professor wants
to switch it more often :-)

For the voltage regulator you could use something like the LP2981 for $0.80
from Digikey for 3.3V output voltage, which works then for input voltages
up to 16V and down to 3.5V. All parts would fit in matchbox.

--
Frank Buss,
http://www.frank-buss.de, http://www.it4-systems.de

Frank Buss wrote:
West wrote:

The professor wants a small box (3"X5")

A 2D box in a 3D world could be difficult. I have to ask my distributor, if
they have some 2D parts.

Next semester we will go further with this but for now, that's all I can
say. Still want to help?

Do you want that we serve up the homework on a plate to you? Which one of
the many suggested solutions doesn't help you?

I would do it with a microcontroller, because there are ones with
integrated power-on-reset and oscillator, like the MSP430F2111 for $2,25,
so you have to write just about 5 lines of assember code to solve this
task. The datasheet says the integrated flash has a life time of 100,000
erase/program cycles, so this should be fine, unless your professor wants
to switch it more often :-)

Or the PIC12F629

http://ww1.microchip.com/downloads/e...Doc/41190E.pdf

Only $1.75 a piece at Digi-Key, and has 1,000,000 EEPROM erase/program
cycles. Comes in 8 pin DIP package, so it's easy to solder for
beginners. A built-in status register tells you the reason for the
reset, so you can see if it was just powered on. It also has a wide
2V-5.5V operating voltage and high current I/O pins.

Arlet Ottens wrote:

Or the PIC12F629

http://ww1.microchip.com/downloads/e...Doc/41190E.pdf

Only $1.75 a piece at Digi-Key, and has 1,000,000 EEPROM erase/program
cycles.

Looks nice.

Looking at the datasheet, there is a patent cited:

http://www.google.com/patents?id=soI...J&dq=5,847,450

They are kidding, right? They can't patent the "invention" that a
microcontroller with n bits data bus has n pins, can they?

--
Frank Buss,
http://www.frank-buss.de, http://www.it4-systems.de

Frank Buss posted to sci.electronics.design:

Arlet Ottens wrote:

Or the PIC12F629

http://ww1.microchip.com/downloads/e...Doc/41190E.pdf

Only $1.75 a piece at Digi-Key, and has 1,000,000 EEPROM
erase/program cycles.

Looks nice.

Looking at the datasheet, there is a patent cited:

http://www.google.com/patents?id=soI...J&dq=5,847,450

They are kidding, right? They can't patent the "invention" that a
microcontroller with n bits data bus has n pins, can they?


No, just some other tiny aspect of the device.