Please advice (which chip to count up/down and DAC)

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MAGL
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Posted by MAGL: Wed. Jun 16, 2010 - 09:56 AM
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I need 2 inputs for UP and DOWN and 1 analogue output for voltage controlled application 10-15V.
5 bit resulation is sufficient . Nonvolatile is a must
There is no room, I can only use 8 pin dip.
Any help would be appreciated.

[moderator: stupid thread title amended]

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AVR Microcontrollers, megaAVR and tinyAVR
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Bronze Markdavid.prentice
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Posted by david.prentice: Wed. Jun 16, 2010 - 10:06 AM
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Your two inputs are regular GPIO pins with internal pull-ups. You 'make' the switch by grounding.

Your 10-15V o/p is more difficult.
You can produce a variable voltage with a PWM o/p and low-pass filter.

I suppose you could apply the PWM to a voltage tripler circuit.

Any 8 pin AVR would do this. Obviously the voltage tripler will not like a heavy loading.

David.

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MAGL
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Posted by MAGL: Wed. Jun 16, 2010 - 10:27 AM
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Thank you very much for your PROMPT response

david.prentice wrote:
Your two inputs are regular GPIO pins with internal pull-ups. You 'make' the switch by grounding.

It is okay, I am using opto-coupler

Your 10-15V o/p is more difficult.
You can produce a variable voltage with a PWM o/p and low-pass filter.

I can shift the voltage

I suppose you could apply the PWM to a voltage tripler circuit.

Any 8 pin AVR would do this. Obviously the voltage tripler will not like a heavy loading.

David.

What about the nonvolatile issue

Sorry for the all questions I am newbie.
I have STK500 board but I have no time to work with it.
Regards,

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JimK
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Posted by JimK: Wed. Jun 16, 2010 - 10:28 AM
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MAGL wrote:
... and 1 analogue output for voltage controlled application 10-15V

You could use PWM output and LP filter as advised above, plus an external opamp with gain of *3 for example.
The opamp's DC supply rail would have to be 15v or more though.

On second thoughts though, if we're going to this much trouble, we could use an external DAC instead, but we still have the 15v supply rail problem.

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Gold Markclawson
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Posted by clawson: Wed. Jun 16, 2010 - 10:39 AM
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WHAT needs to be "nonvolatile"? If you are talking about permanently held (but variable) settings then I think all AVRs have at least some bytes of EEPROM for this.

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Kartman
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Posted by Kartman: Wed. Jun 16, 2010 - 10:53 AM
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Quote:
I have STK500 board but I have no time to work with it.

If you don't have the time , then waiting for our answers means we are too late!

No time ,must be 8pin dip,no space, non-volatile....

Tight constraints!

Last Edited: Wed. Jun 16, 2010 - 10:54 AM
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timgoh0
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Posted by timgoh0: Wed. Jun 16, 2010 - 10:53 AM
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http://www.onsemi.com/PowerSolut...

Onsemi has some digital potentiometers, which seems to meet OP's requirements. The CAT5133 has a V_hi of 16V, and it comes in MSOP, which is smaller than 8DIP

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ArnoldB
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Posted by ArnoldB: Wed. Jun 16, 2010 - 07:01 PM
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MAGL wrote:
I have STK500 board but I have no time to work with it.
So your time is more valuable than our time? I don't think so.

Stealing Proteus doesn't make you an engineer.

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MAGL
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Posted by MAGL: Fri. Jun 18, 2010 - 02:37 PM
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ArnoldB wrote:
MAGL wrote:
I have STK500 board but I have no time to work with it.
So your time is more valuable than our time? I don't think so.

I am very sorry. I just want to say I need some help an I have no time to find correct IC and develop my project.
I apologize to disturb you.

For the others:
Please advice which IC is suitable:
Up and Down inputs
Pwm output (analogue output)
Look up table
8 pin dip
Minimum external component

Regards

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Gold Markclawson
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Posted by clawson: Fri. Jun 18, 2010 - 02:41 PM
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Well I'd say all the AVRs (tinys and megas) would meet all of your requirements APART from the 8pin DIP requirement. So head over to:

http://www.atmel.com/dyn/product...

and search "PDIP 8". I make that:

tiny13A
tiny25
tiny45
tiny85

Which of those you choose will probably then be determined by size of "Look up table" (and complexity/size of code)

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