AVR-Chat

I am trying to develop DAC circuitry for Atmega 16 since Atmega16
doesn't have in-built feature of DAC. The circuitry design will be 4X
DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC 
circuit would be using 11 ports lines of Atmega16 where PortC0-PortC7 
would be input to the 8-bit parallel AD7528 chip and 3 ports lines 
(PortD0-Port2)would be used as control line inputs. The requirement of 
this DAC circuit is that it would produce variable voltage (0DVc - 
10DVc) at fix current of 25mA. I will plan to locate Op Amp in the 
output of every AD7528 DAC chip. 

I am not trying to ask anyone to do homework for me but I may treat
here as a resource to gain ideas for the development I am working on.
I will appreaciate anyone helping me by having discussions and making
suggestions related to this topic. Kindly show me any link related to 
this topic if u know any. Best Regards.

Yeah I know. In fact MCP4725 is my first choice but since I couldn't 
get it from the shop here, I would go with AD7528. So, any 
suggestion to design the 4X DAC using AD7528 for Atmega16? I crack 
my mind to search for this topic using Google but to no avail. 


--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" <RBurrage@...> 
wrote:
>
> You might do better using something like a Microchip MCP4922.  It 
has a 
> serial SPI interface, 12 bit accuracy, 14 pin dip package, dual 
DAC, and 
> rail to rail outputs for starters.  We use the MCP4921 single DAC 
> version here regularly with good results.  We have used the '4922 
in a 
> couple of applications with good results too.  This would give you 
a 
> smaller package, higher accuracy module with better crosstalk, 
lower 
> power consumption, and better temperature specifications.  They 
only 
> operate at 5 volts, but if you need higher voltage operation you'd 
have 
> to add interface circuitry anyway between your controller and your 
DAC.
> 
> They're cheap, too.
> 
> 
> REB
> 
> 
> huiyangdoh wrote:
> 
> >I am trying to develop DAC circuitry for Atmega 16 since Atmega16
> >doesn't have in-built feature of DAC. The circuitry design will 
be 4X
> >DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC 
> >circuit would be using 11 ports lines of Atmega16 where PortC0-
PortC7 
> >would be input to the 8-bit parallel AD7528 chip and 3 ports 
lines 
> >(PortD0-Port2)would be used as control line inputs. The 
requirement of 
> >this DAC circuit is that it would produce variable voltage (0DVc -
 
> >10DVc) at fix current of 25mA. I will plan to locate Op Amp in 
the 
> >output of every AD7528 DAC chip. 
> >
> >I am not trying to ask anyone to do homework for me but I may 
treat
> >here as a resource to gain ideas for the development I am working 
on.
> >I will appreaciate anyone helping me by having discussions and 
making
> >suggestions related to this topic. Kindly show me any link 
related to 

> >this topic if u know any. Best Regards.  
> >
> >
> >  
> >
>

You might do better using something like a Microchip MCP4922.  It has a 
serial SPI interface, 12 bit accuracy, 14 pin dip package, dual DAC, and 
rail to rail outputs for starters.  We use the MCP4921 single DAC 
version here regularly with good results.  We have used the '4922 in a 
couple of applications with good results too.  This would give you a 
smaller package, higher accuracy module with better crosstalk, lower 
power consumption, and better temperature specifications.  They only 
operate at 5 volts, but if you need higher voltage operation you'd have 
to add interface circuitry anyway between your controller and your DAC.

They're cheap, too.


REB


huiyangdoh wrote:

>I am trying to develop DAC circuitry for Atmega 16 since Atmega16
>doesn't have in-built feature of DAC. The circuitry design will be 4X
>DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC 
>circuit would be using 11 ports lines of Atmega16 where PortC0-PortC7 
>would be input to the 8-bit parallel AD7528 chip and 3 ports lines 
>(PortD0-Port2)would be used as control line inputs. The requirement of 
>this DAC circuit is that it would produce variable voltage (0DVc - 
>10DVc) at fix current of 25mA. I will plan to locate Op Amp in the 
>output of every AD7528 DAC chip. 
>
>I am not trying to ask anyone to do homework for me but I may treat
>here as a resource to gain ideas for the development I am working on.
>I will appreaciate anyone helping me by having discussions and making
>suggestions related to this topic. Kindly show me any link related to 
>this topic if u know any. Best Regards.  
>
>
>  
>

It is a good suggestion to use MCP4922 since it is cheaper than 
AD7528 but it is running out of stock over here. I could get AD7528 
though. Anyway, can you show me how to interface MCP4922 with Atmega 
16 if it were to design 4xDAC and also some of the codes? Regards.





--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" <RBurrage@...> 
wrote:
>
> The '7528 is over 30 years old...1970s technology.  I don't 
remember if 
> it was invented by Precision Monolithics or Analog Devices with 
PMI as a 
> second source, but it's old technology and if you're developing a 
> product intending to use them you'll eventually have issues trying 
to 
> buy them.  With their parallel interface they also require more 
lines to 
> talk back and forth.
> 
> If you insist upon using the AD7528, the datasheet has fairly 
complete 
> information as to how to interface with your controller.  If need 
be you 
> can also go to the Analog Devices web site for application note 
> information.  They generally have good information up there.  You 
might 
> also check to see what the production status of the AD7528 is 
while 
> you're there.
> 
>           http://www.analog.com/en/
> 
> However, the MCP4922 is only about 3 bucks in 1s...and Microchip 
used to 
> be pretty liberal with their sample policy.
> 
> 
> REB
> 
> 
> 
> 
> huiyangdoh wrote:
> 
> >Yeah I know. In fact MCP4725 is my first choice but since I 
couldn't 
> >get it from the shop here, I would go with AD7528. So, any 
> >suggestion to design the 4X DAC using AD7528 for Atmega16? I 
crack 
> >my mind to search for this topic using Google but to no avail. 
> >
> >
> >--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" <RBurrage@> 
> >wrote:
> >  
> >
> >>You might do better using something like a Microchip MCP4922.  
It 
> >>    
> >>
> >has a 
> >  
> >
> >>serial SPI interface, 12 bit accuracy, 14 pin dip package, dual 
> >>    
> >>
> >DAC, and 
> >  
> >
> >>rail to rail outputs for starters.  We use the MCP4921 single 
DAC 
> >>version here regularly with good results.  We have used 
the '4922 
> >>    
> >>
> >in a 
> >  
> >
> >>couple of applications with good results too.  This would give 
you 
> >>    
> >>
> >a 
> >  
> >
> >>smaller package, higher accuracy module with better crosstalk, 
> >>    
> >>
> >lower 
> >  
> >
> >>power consumption, and better temperature specifications.  They 
> >>    
> >>
> >only 
> >  
> >
> >>operate at 5 volts, but if you need higher voltage operation 
you'd 
> >>    
> >>
> >have 
> >  
> >
> >>to add interface circuitry anyway between your controller and 
your 
> >>    
> >>
> >DAC.
> >  
> >
> >>They're cheap, too.
> >>
> >>
> >>REB
> >>
> >>
> >>huiyangdoh wrote:
> >>
> >>    
> >>
> >>>I am trying to develop DAC circuitry for Atmega 16 since 
Atmega16
> >>>doesn't have in-built feature of DAC. The circuitry design will 
> >>>      
> >>>
> >be 4X
> >  
> >
> >>>DAC design using AD7528 DAC Chips. To my understanding,the 4X 
DAC 
> >>>circuit would be using 11 ports lines of Atmega16 where PortC0-
> >>>      
> >>>
> >PortC7 
> >  
> >
> >>>would be input to the 8-bit parallel AD7528 chip and 3 ports 
> >>>      
> >>>
> >lines 
> >  
> >
> >>>(PortD0-Port2)would be used as control line inputs. The 
> >>>      
> >>>
> >requirement of 
> >  
> >
> >>>this DAC circuit is that it would produce variable voltage 
(0DVc -
> >>>      
> >>>
> > 
> >  
> >
> >>>10DVc) at fix current of 25mA. I will plan to locate Op Amp in 
> >>>      
> >>>
> >the 
> >  
> >
> >>>output of every AD7528 DAC chip. 
> >>>
> >>>I am not trying to ask anyone to do homework for me but I may 
> >>>      
> >>>
> >treat
> >  
> >
> >>>here as a resource to gain ideas for the development I am 
working 

> >>>      
> >>>
> >on.
> >  
> >
> >>>I will appreaciate anyone helping me by having discussions and 
> >>>      
> >>>
> >making
> >  
> >
> >>>suggestions related to this topic. Kindly show me any link 
> >>>      
> >>>
> >related to 
> >  
> >
> >>>this topic if u know any. Best Regards.  
> >>>
> >>>
> >>> 
> >>>
> >>>      
> >>>
> >
> >
> >
> >
> > 
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >  
> >
> 
> 
> [Non-text portions of this message have been removed]
>

The '7528 is over 30 years old...1970s technology.  I don't remember if 
it was invented by Precision Monolithics or Analog Devices with PMI as a 
second source, but it's old technology and if you're developing a 
product intending to use them you'll eventually have issues trying to 
buy them.  With their parallel interface they also require more lines to 
talk back and forth.

If you insist upon using the AD7528, the datasheet has fairly complete 
information as to how to interface with your controller.  If need be you 
can also go to the Analog Devices web site for application note 
information.  They generally have good information up there.  You might 
also check to see what the production status of the AD7528 is while 
you're there.

          http://www.analog.com/en/

However, the MCP4922 is only about 3 bucks in 1s...and Microchip used to 
be pretty liberal with their sample policy.


REB




huiyangdoh wrote:

>Yeah I know. In fact MCP4725 is my first choice but since I couldn't 
>get it from the shop here, I would go with AD7528. So, any 
>suggestion to design the 4X DAC using AD7528 for Atmega16? I crack 
>my mind to search for this topic using Google but to no avail. 
>
>
>--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" <RBurrage@...> 
>wrote:
>  
>
>>You might do better using something like a Microchip MCP4922.  It 
>>    
>>
>has a 
>  
>
>>serial SPI interface, 12 bit accuracy, 14 pin dip package, dual 
>>    
>>
>DAC, and 
>  
>
>>rail to rail outputs for starters.  We use the MCP4921 single DAC 
>>version here regularly with good results.  We have used the '4922 
>>    
>>
>in a 
>  
>
>>couple of applications with good results too.  This would give you 
>>    
>>
>a 
>  
>
>>smaller package, higher accuracy module with better crosstalk, 
>>    
>>
>lower 
>  
>
>>power consumption, and better temperature specifications.  They 
>>    
>>
>only 
>  
>
>>operate at 5 volts, but if you need higher voltage operation you'd 
>>    
>>
>have 
>  
>
>>to add interface circuitry anyway between your controller and your 
>>    
>>
>DAC.
>  
>
>>They're cheap, too.
>>
>>
>>REB
>>
>>
>>huiyangdoh wrote:
>>
>>    
>>
>>>I am trying to develop DAC circuitry for Atmega 16 since Atmega16
>>>doesn't have in-built feature of DAC. The circuitry design will 
>>>      
>>>
>be 4X
>  
>
>>>DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC 
>>>circuit would be using 11 ports lines of Atmega16 where PortC0-
>>>      
>>>
>PortC7 
>  
>
>>>would be input to the 8-bit parallel AD7528 chip and 3 ports 
>>>      
>>>
>lines 
>  
>
>>>(PortD0-Port2)would be used as control line inputs. The 
>>>      
>>>
>requirement of 
>  
>
>>>this DAC circuit is that it would produce variable voltage (0DVc -
>>>      
>>>
> 
>  
>
>>>10DVc) at fix current of 25mA. I will plan to locate Op Amp in 
>>>      
>>>
>the 
>  
>
>>>output of every AD7528 DAC chip. 
>>>
>>>I am not trying to ask anyone to do homework for me but I may 
>>>      
>>>
>treat
>  
>
>>>here as a resource to gain ideas for the development I am working 
>>>      
>>>
>on.
>  
>
>>>I will appreaciate anyone helping me by having discussions and 
>>>      
>>>
>making
>  
>
>>>suggestions related to this topic. Kindly show me any link 
>>>      
>>>
>related to 
>  
>
>>>this topic if u know any. Best Regards.  
>>>
>>>
>>> 
>>>
>>>      
>>>
>
>
>
>
> 
>Yahoo! Groups Links
>
>
>
>
>
>  
>


[Non-text portions of this message have been removed]

It's all in the datasheet.  I suggest you look there first and write 
your code.  Then if you have problems getting your code to work you can 
ask specific questions,  maybe post your code and we'll try to help you.

Grandpa always told us when we were kids that when you need a hand, look 
at the end of your own arm first.

If you're in school, we aren't interested in doing your work for you 
unless we share your grade...and since most of us are finished with 
school, we don't need or care about grades on assignments or class projects.

If you're working on a product and want us to do all of the work for 
you, you need to be willing to share your profits...most of them, 
actually.  Most of us who do embedded processor work are in a position 
such that if we no workie we get no checkie...the corollary to that is, 
no checkie no workie.

Look on the end of your arm first.


REB



huiyangdoh wrote:

>It is a good suggestion to use MCP4922 since it is cheaper than 
>AD7528 but it is running out of stock over here. I could get AD7528 
>though. Anyway, can you show me how to interface MCP4922 with Atmega 
>16 if it were to design 4xDAC and also some of the codes? Regards.
>
>
>
>
>
>--- In AVR-Chat@yahoogroups.com, "Roy E. Burrage" <RBurrage@...> 
>wrote:
>  
>
>>The '7528 is over 30 years old...1970s technology.  I don't 
>>    
>>
>remember if 
>  
>
>>it was invented by Precision Monolithics or Analog Devices with 
>>    
>>
>PMI as a 
>  
>
>>second source, but it's old technology and if you're developing a 
>>product intending to use them you'll eventually have issues trying 
>>    
>>
>to 
>  
>
>>buy them.  With their parallel interface they also require more 
>>    
>>
>lines to 
>  
>
>>talk back and forth.
>>
>  
>


[Non-text portions of this message have been removed]

D0..7, WR*, DAC1*/DAC2 lines can be shared between the multiple 
AD7528's.  You will need seperate CS* lines for each AD7528, this way 
you can select which DAC chip you are selecting to write to, all the 
other control lines can be in common and work together.

John C

huiyangdoh wrote:

>
> Yeah I know. In fact MCP4725 is my first choice but since I couldn't
> get it from the shop here, I would go with AD7528. So, any
> suggestion to design the 4X DAC using AD7528 for Atmega16? I crack
> my mind to search for this topic using Google but to no avail.
>
> --- In AVR-Chat@yahoogroups.com <mailto:AVR-Chat%40yahoogroups.com>, 
> "Roy E. Burrage" <RBurrage@...>
> wrote:
> >
> > You might do better using something like a Microchip MCP4922. It
> has a
> > serial SPI interface, 12 bit accuracy, 14 pin dip package, dual
> DAC, and
> > rail to rail outputs for starters. We use the MCP4921 single DAC
> > version here regularly with good results. We have used the '4922
> in a
> > couple of applications with good results too. This would give you
> a
> > smaller package, higher accuracy module with better crosstalk,
> lower
> > power consumption, and better temperature specifications. They
> only
> > operate at 5 volts, but if you need higher voltage operation you'd
> have
> > to add interface circuitry anyway between your controller and your
> DAC.
> >
> > They're cheap, too.
> >
> >
> > REB
> >
> >
> > huiyangdoh wrote:
> >
> > >I am trying to develop DAC circuitry for Atmega 16 since Atmega16
> > >doesn't have in-built feature of DAC. The circuitry design will
> be 4X
> > >DAC design using AD7528 DAC Chips. To my understanding,the 4X DAC
> > >circuit would be using 11 ports lines of Atmega16 where PortC0-
> PortC7
> > >would be input to the 8-bit parallel AD7528 chip and 3 ports
> lines
> > >(PortD0-Port2)would be used as control line inputs. The
> requirement of
> > >this DAC circuit is that it would produce variable voltage (0DVc -
>
> > >10DVc) at fix current of 25mA. I will plan to locate Op Amp in
> the
> > >output of every AD7528 DAC chip.
> > >
> > >I am not trying to ask anyone to do homework for me but I may
> treat
> > >here as a resource to gain ideas for the development I am working
> on.
> > >I will appreaciate anyone helping me by having discussions and
> making
> > >suggestions related to this topic. Kindly show me any link
> related to
> > >this topic if u know any. Best Regards.
> > >
> > >
> > >
> > >
> >
>
>

At 08:18 PM 9/12/2007, you wrote:
>11 ports lines of Atmega16 where PortC0-PortC7
>would be input to the 8-bit parallel AD7528 chip

If you can avoid the use of portc2-portc5 for the chip,
then you will have the JTAG port available for debugging
or programming without too much messing around.


Regards

John Samperi

********************************************************
Ampertronics Pty. Ltd.
11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
Tel. (02) 9674-6495       Fax (02) 9674-8745
Email: john@ampertronics.com.au
Website  http://www.ampertronics.com.au
*Electronic Design * Custom Products * Contract Assembly
********************************************************

I have come out with the exact schematic and algorithm for DAC 
program  using AD7528. Assume you connect to the following:

   1. 8 x bit Data input you can connect to all of Atmega Port D,
   2. For CS, DAC A/B & WRITE, you can connect to Port C [pin 0, 1,
2] respectively,

For algorithm,

    1. Set All of Port D to output mode, and
    2, Port C [0,1,2] also to output mode and set to high.
    3. To Write data ,

         -    Write 8 output data to Port D,
         -    Select DAC A/D, by write 1 bit data to Port C1,
         -    Bring CS pin to low by write '0' to Port C0,
         -    Bring WRITE pin to low by write '0' to Port C2.

        after that you bring the WRITE & CS pin to high by
             Write '1' to Port C2, and write '1' to Port 0.


Any idea on the actual code? 





--- In AVR-Chat@yahoogroups.com, John Samperi <samperi@...> wrote:

>
> At 08:18 PM 9/12/2007, you wrote:
> >11 ports lines of Atmega16 where PortC0-PortC7
> >would be input to the 8-bit parallel AD7528 chip
> 
> If you can avoid the use of portc2-portc5 for the chip,
> then you will have the JTAG port available for debugging
> or programming without too much messing around.
> 
> 
> Regards
> 
> John Samperi
> 
> ********************************************************
> Ampertronics Pty. Ltd.
> 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
> Tel. (02) 9674-6495       Fax (02) 9674-8745
> Email: john@...
> Website  http://www.ampertronics.com.au
> *Electronic Design * Custom Products * Contract Assembly
> ********************************************************
>

Nice work. 

If you have to ask about actual code with a fairly straight forward 
algorithm like that, then you either need to read your datasheets some 
more, or hire a programmer. 

If I assume you have the rest of the program done, then you must be 
struggling with AVR specific part of IO programming.  This is VERY easy 
for general pin functions - all VERY well described in the datasheet.  
If you are using GCC/WinAVR C compiler, the avr-libc has defined all IO 
registers needed to implement this - specifically DDRD, PORTD, DDRC and 
PORTC.  Depending on MCU clock speed, you may need to insert some delays 
between the steps of your algorithm to provide the necessary bus timing 
for the DAC.

If you haven't even started programming the remainder of your program, 
and need help writing a program from scratch, ask your instructor.  Or, 
start out by writing the embedded equivelent of Hello World - that is - 
hood a LED to one of the IO pins and start a program to toggle the pin.  
This would require a delay loop so as to slow the blinking down to the 
point of being visible.  Heck, you could even implement a delay routine 
that you could re-use later (like delay_ms - delay x # of milli-seconds, 
which could use delay_us - delay # of micro-seconds.)

If you are new to C and to the AVR, you may want to look to BASIC - use 
BASCOM, it has a nice library that would make your programming somewhat 
easier.  If your instructor insists on assembly or C, then you are on 
your own to do your homework.

John Clymer

huiyangdoh wrote:

>
> I have come out with the exact schematic and algorithm for DAC
> program using AD7528. Assume you connect to the following:
>
> 1. 8 x bit Data input you can connect to all of Atmega Port D,
> 2. For CS, DAC A/B & WRITE, you can connect to Port C [pin 0, 1,
> 2] respectively,
>
> For algorithm,
>
> 1. Set All of Port D to output mode, and
> 2, Port C [0,1,2] also to output mode and set to high.
> 3. To Write data ,
>
> - Write 8 output data to Port D,
> - Select DAC A/D, by write 1 bit data to Port C1,
> - Bring CS pin to low by write '0' to Port C0,
> - Bring WRITE pin to low by write '0' to Port C2.
>
> after that you bring the WRITE & CS pin to high by
> Write '1' to Port C2, and write '1' to Port 0.
>
> Any idea on the actual code?
>
> --- In AVR-Chat@yahoogroups.com <mailto:AVR-Chat%40yahoogroups.com>, 
> John Samperi <samperi@...> wrote:
> >
> > At 08:18 PM 9/12/2007, you wrote:
> > >11 ports lines of Atmega16 where PortC0-PortC7
> > >would be input to the 8-bit parallel AD7528 chip
> >
> > If you can avoid the use of portc2-portc5 for the chip,
> > then you will have the JTAG port available for debugging
> > or programming without too much messing around.
> >
> >
> > Regards
> >
> > John Samperi
> >
> > ********************************************************
> > Ampertronics Pty. Ltd.
> > 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
> > Tel. (02) 9674-6495 Fax (02) 9674-8745
> > Email: john@...
> > Website http://www.ampertronics.com.au <http://www.ampertronics.com.au>
> > *Electronic Design * Custom Products * Contract Assembly
> > ********************************************************
> >
>
>

On the surface, your algorithm makes sense for what you're doing.

As for help writing the code, if you need help with that you need to work on
the specific language you're having problems with.  I think the purpose of
this group is to work out processor specific issues, not general programming
ones.

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of huiyangdoh
Sent: Sunday, December 09, 2007 6:25 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Re: 4X DAC Design using Atmega16 and AD7528 IC

I have come out with the exact schematic and algorithm for DAC 
program  using AD7528. Assume you connect to the following:

   1. 8 x bit Data input you can connect to all of Atmega Port D,
   2. For CS, DAC A/B & WRITE, you can connect to Port C [pin 0, 1,
2] respectively,

For algorithm,

    1. Set All of Port D to output mode, and
    2, Port C [0,1,2] also to output mode and set to high.
    3. To Write data ,

         -    Write 8 output data to Port D,
         -    Select DAC A/D, by write 1 bit data to Port C1,
         -    Bring CS pin to low by write '0' to Port C0,
         -    Bring WRITE pin to low by write '0' to Port C2.

        after that you bring the WRITE & CS pin to high by
             Write '1' to Port C2, and write '1' to Port 0.


Any idea on the actual code? 





--- In AVR-Chat@yahoogroups.com, John Samperi <samperi@...> wrote:
>
> At 08:18 PM 9/12/2007, you wrote:
> >11 ports lines of Atmega16 where PortC0-PortC7
> >would be input to the 8-bit parallel AD7528 chip
> 
> If you can avoid the use of portc2-portc5 for the chip,
> then you will have the JTAG port available for debugging
> or programming without too much messing around.
> 
> 
> Regards
> 
> John Samperi
> 
> ********************************************************
> Ampertronics Pty. Ltd.
> 11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
> Tel. (02) 9674-6495       Fax (02) 9674-8745
> Email: john@...
> Website  http://www.ampertronics.com.au
> *Electronic Design * Custom Products * Contract Assembly
> ********************************************************
>




 
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