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

Log in or register to post comments
Go To Last Post
10 posts / 0 new
Author
Message
MAGL
MAGL's picture
Level: Rookie
Joined: Wed. Jun 16, 2010
Posts: 28 View posts
#1
Posted by MAGL: Wed. Jun 16, 2010 - 09:56 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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]

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
Top
Bronze Markdavid.prentice
david.prentice's picture
Level: 10k+ Postman
Joined: Sat. Feb 12, 2005
Posts: 29964 View posts
Location: Wormshill, England
Posted by david.prentice: Wed. Jun 16, 2010 - 10:06 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

Top
MAGL
MAGL's picture
Level: Rookie
Joined: Wed. Jun 16, 2010
Posts: 28 View posts
Posted by MAGL: Wed. Jun 16, 2010 - 10:27 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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,

Top
JimK
JimK's picture
Level: Hangaround
Joined: Fri. Jun 17, 2005
Posts: 494 View posts
Location: New Zealand
Posted by JimK: Wed. Jun 16, 2010 - 10:28 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

Top
Silver Markclawson
clawson's picture
Level: Moderator
Joined: Mon. Jul 18, 2005
Posts: 99918 View posts
Location: (using avr-gcc in) Finchingfield, Essex, England
Posted by clawson: Wed. Jun 16, 2010 - 10:39 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

Top
Kartman
Kartman's picture
Level: 10k+ Postman
Joined: Thu. Dec 30, 2004
Posts: 24226 View posts
Location: Melbourne,Australia
Posted by Kartman: Wed. Jun 16, 2010 - 10:53 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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
Top
timgoh0
timgoh0's picture
Level: Hangaround
Joined: Sun. Apr 6, 2008
Posts: 409 View posts
Location: Singapore
Posted by timgoh0: Wed. Jun 16, 2010 - 10:53 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
ArnoldB
ArnoldB's picture
Level: Raving Lunatic
Joined: Thu. Nov 29, 2007
Posts: 3188 View posts
Posted by ArnoldB: Wed. Jun 16, 2010 - 07:01 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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.

Top
MAGL
MAGL's picture
Level: Rookie
Joined: Wed. Jun 16, 2010
Posts: 28 View posts
Posted by MAGL: Fri. Jun 18, 2010 - 02:37 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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

Top
Silver Markclawson
clawson's picture
Level: Moderator
Joined: Mon. Jul 18, 2005
Posts: 99918 View posts
Location: (using avr-gcc in) Finchingfield, Essex, England
Posted by clawson: Fri. Jun 18, 2010 - 02:41 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

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)

Top