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Analog output

B

BR

Jan 1, 1970
0
Looking for inexpensive 12-bit analog output and a few i/o lines via parallel
port. Schematics, products?
 
R

R. Steve Walz

Jan 1, 1970
0
BR said:
Looking for inexpensive 12-bit analog output and a few i/o lines via parallel
port. Schematics, products?
--------------
Inexpensive, use 74HC574 octal latches, and a 12 bit R-2R ladder DAC.

http://www.armory.com/~rstevew/Public/R-2R_DACs/
http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2RLadderDAC.gif
http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2R_10DAC.gif
http://www.armory.com/~rstevew/Public/R-2R_DACs/R-2R_8bitDAC.gif

http://www.armory.com/~rstevew/Public/Tutor/PinOuts/parallel.gif

Use the control lines pins 1, 14, 16, 17 to strobe the latches.

-Steve
 
J

John Fortier

Jan 1, 1970
0
BR said:
Looking for inexpensive 12-bit analog output and a few i/o lines via parallel
port. Schematics, products?

Better definition needed. Words please and thankyou omitted. Desire to
help not evoked.

John
 
B

BR

Jan 1, 1970
0
Ok, I need to control one Servodisc motor. The H-bridge for the motor has a
voltage input that controls the PWM. It also has two ports for forward and
reverse signals. I was looking around and found a simple schematic for an 8
bit d/a (AD7524) which is apparenty nothing more than connecting the 8 data
lines of the parallel port to the DAC. Now I may just try getting along with 8
bit resolution, but if I need more resolution, how do I load two bytes into a
12 bit DAC? (realizing that 4 bits will be discarded). I will probably figure
out this simple project myself eventually, however perhaps there is a way I
could be prevented from using more chips than necessary to accomplish this.

Help appreciated.

Ben
 
J

John Fortier

Jan 1, 1970
0
BR said:
Please?

Thank you.

Ben
OK Ben, Go to rswww.com. You'll need to register, which is free, and then
you can search out DACs from the electronics section. You can download
manufacturers data sheets in PDF and choose the DAC which comes closest to
your requirements. You don't have to order anything to get all the
information, and, since they are a UK company, you may not want to pay the
shipping charges, although if it comes by mail, it's cheap.

I use RS not only as a supplier, but also as a research tool when it comes
to choosing suitable components for prototypes.

Regards

John
 
B

BR

Jan 1, 1970
0
John, I can't register. Doesn't recognize US zip code. I download data sheets
from various mfr's websites anyway. The DAC isn't critical.

Regarding what I'm trying to figure out, this pdf

http://www.physics.otago.ac.nz/electronics/papers/HicksBahr99.pdf

shows a 12 bit ADC feeding a parallel port. Although they are utilizing EPP
mode, SPP will be fast enough. It's just that part of the circuit that buffers
the 4 bits from the ADC that's later transferred to the parallel port that I'm
interested in, or for a DAC the situation would be reversed.

How about this DAC1222
http://www.jameco.com/Jameco/Products/ProdDS/14980.pdf

Ben
[/QUOTE]
OK Ben, Go to rswww.com. You'll need to register, which is free, and then
you can search out DACs from the electronics section. You can download
manufacturers data sheets in PDF and choose the DAC which comes closest to
your requirements. You don't have to order anything to get all the
information, and, since they are a UK company, you may not want to pay the
shipping charges, although if it comes by mail, it's cheap.

I use RS not only as a supplier, but also as a research tool when it comes
to choosing suitable components for prototypes.

Regards

John
[/QUOTE]
 
W

Wade Hassler

Jan 1, 1970
0
BR said:
Ok, I need to control one Servodisc motor. The H-bridge for the motor has a
voltage input that controls the PWM. It also has two ports for forward and
reverse signals. I was looking around and found a simple schematic for an 8
bit d/a (AD7524) which is apparenty nothing more than connecting the 8 data
lines of the parallel port to the DAC. Now I may just try getting along with 8
bit resolution, but if I need more resolution, how do I load two bytes into a
12 bit DAC? (realizing that 4 bits will be discarded). I will probably figure
out this simple project myself eventually, however perhaps there is a way I
could be prevented from using more chips than necessary to accomplish this.

Help appreciated.

Ben
The schematic in the paper you referenced shows how:
Put upper 4 bits on parallel port data lines
Latch upper 4 bits to 74x574 with a control line
Put lower 8 bits on parallel port data lines
Send 12 bits to DAC with another control line


Wade
 
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