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DAC software

D

DL

Jan 1, 1970
0
Hi,

I would like to incorporate a DAC in a board design so as to provide
some biases in the rest of the circuit and was wondering if anyone
knows if any company provides software that could program their DAC
through the serial or parallel port. Unfortunately, there is not much
time for designing and testing so I don't have time to write the
program myself. There are no tight specifications on the DAC
(preferably running at 3.3V and accuracies of 10bits and up are fine)
so basically any DAC will do as long as it has ready software to
program it.

Thanks in advance for any suggestions.
 
N

nyboard

Jan 1, 1970
0
Hi, I guess you need to look for the sample program from the
microprocessor datasheep or application note. If you are using PIC,
perhaps you can find the program from the microchip website or just
google it. Good luck!
 
D

DL

Jan 1, 1970
0
Sorry, I forgot to mention that I meant discrete DACs rather than
embedded into a microprocessor. Ideally I would like 8 of them in one
package. LTC and Analog Devices have some but the software they
provide is meant only for their evaluation kit.
 
This does not make any sense.

What processor are you using ?
What is it programmed in, C, Assembly, Forth, BASIC, FORTRAN.... What ??

You don't have time to do it right, but you must have enough money to do
it over.

good luck

donald

The fact products get designed and sold with such a lackadaisical
attitude is mind boggling. I expect this in software, but not
hardware.

Personally, this sounds like an application for those digital
potentiometers made by Microchip and others. Also, 10 bits for bias
sounds excessive. If trim is being done, you get close with resistors
then tweak with the pot.
 
D

DL

Jan 1, 1970
0
Joel is partly right. I indeed am a hardware design guy, but there is
nobody else who will do the software. So it should be either available
by the company that makes the DACs or I have to write it on my own.

I have programmed in the past similar devices (e.g. ADCs) and one can
directly program them using a computer and the parallel or serial
port. The program can be written in any language and is easy in its
concept. The problem is that I don't have time much time and that's
why I was wondering if there is a ready solution.

m...@sushi you are right. A 10bit accuracy is not needed but 10bit (or
actually 8bit) is the lowest you can find available anyways for a DAC.
Using pots to tweak the bias values has the problem of drifting and
adjustment is needed every once in a while. DACs don't have this
problem and if ones with memory are used, then they just need to be
programmed once and not every time the power is turned on. Another
aspect is that I need 8 biases and therefore an octal DAC will use
much less space than 8 pots.

So basically my question in the post was if anyone has used or knows
of a simple program that runs on a PC and uses parallel or serial
interface and that can directly provide the right sequence of signals
for a DAC to be programmed. A microprocessor or microcontroller is not
needed.

Any help will be greatly appreciated.
 
R

Rich Grise

Jan 1, 1970
0
I would like to incorporate a DAC in a board design so as to provide
some biases in the rest of the circuit and was wondering if anyone
knows if any company provides software that could program their DAC
through the serial or parallel port. Unfortunately, there is not much
time for designing and testing so I don't have time to write the
program myself. There are no tight specifications on the DAC
(preferably running at 3.3V and accuracies of 10bits and up are fine)
so basically any DAC will do as long as it has ready software to
program it.

"Program" a DAC??? Why not just get one with a parallel interface and
write to the silly thing? For example, one I remember from cave-man days
is the MC1488, which just has 8 input pins, and when you write your
data to it (via a latch, probably), it just puts out the corresponding
current, which can be converted to a voltage with a resistor.

Good Luck!
Rich
 
R

Rich Grise

Jan 1, 1970
0
The fact products get designed and sold with such a lackadaisical
attitude is mind boggling. I expect this in software, but not
hardware.

Personally, this sounds like an application for those digital
potentiometers made by Microchip and others. Also, 10 bits for bias
sounds excessive. If trim is being done, you get close with resistors
then tweak with the pot.

It sounds like f'in homework, is what it sounds like.

Thanks,
Rich
 
R

Rich Grise

Jan 1, 1970
0
.
So basically my question in the post was if anyone has used or knows
of a simple program that runs on a PC and uses parallel or serial
interface and that can directly provide the right sequence of signals
for a DAC to be programmed. A microprocessor or microcontroller is not
needed.

There is no program needed. No program at all, other than the ability
to output an 8-bit byte out the parallel port. And latch it, of course,
but that's hardware.

Latch the byte, and give it to any ordinary 8-bit DAC - Digi-Key has
hundreds, if not thousands, of them to pick from. Output the byte
through the port, latch it, let the converter convert it, and you're
done!

And don't top-post.

Good Luck!
Rich
 
V

Vladimir Vassilevsky

Jan 1, 1970
0
Rich Grise wrote:

"Program" a DAC??? Why not just get one with a parallel interface and
write to the silly thing?

Bit banging into the serial DAC from the parallel port is very simple also.
For example, one I remember from cave-man days
is the MC1488, which just has 8 input pins, and when you write your
data to it

That was in the old good cave man days. In our days, you will need a
kernel level driver to access the PC parallel port directly. BTW, there
could very well be no such thing as the parallel port at all :)



Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
 
Joel is partly right. I indeed am a hardware design guy, but there is
nobody else who will do the software. So it should be either available
by the company that makes the DACs or I have to write it on my own.

I have programmed in the past similar devices (e.g. ADCs) and one can
directly program them using a computer and the parallel or serial
port. The program can be written in any language and is easy in its
concept. The problem is that I don't have time much time and that's
why I was wondering if there is a ready solution.

m...@sushi you are right. A 10bit accuracy is not needed but 10bit (or
actually 8bit) is the lowest you can find available anyways for a DAC.
Using pots to tweak the bias values has the problem of drifting and
adjustment is needed every once in a while. DACs don't have this
problem and if ones with memory are used, then they just need to be
programmed once and not every time the power is turned on. Another
aspect is that I need 8 biases and therefore an octal DAC will use
much less space than 8 pots.

So basically my question in the post was if anyone has used or knows
of a simple program that runs on a PC and uses parallel or serial
interface and that can directly provide the right sequence of signals
for a DAC to be programmed. A microprocessor or microcontroller is not
needed.

Any help will be greatly appreciated.

Actually, I suggested digital potentiometers, not a real trim pot. The
nice thing is they have eeprom, so once "trimmed", they wake up in the
right state (value). I don't know what your project is, but some
system designers like the box to stabilize before tweaking. So they
wake up in the last state, then once running a while the user is
requested if they want higher accuracy.

Here is some random hit:
http://ww1.microchip.com/downloads/en/DeviceDoc/22017a.pdf

By no means is the market limited to microchip.
 
Bit banging into the serial DAC from the parallel port is very simple also.


That was in the old good cave man days. In our days, you will need a
kernel level driver to access the PC parallel port directly. BTW, there
could very well be no such thing as the parallel port at all :)

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

Modern OSs like to own the hardware, which makes hacking difficult.

I'll leave the company name out of it, but we did a bit banging
solution using the dos found on the windows boot disk. I thought it
was cheesy, but not a particularly bad idea. Somehow a virus got on
the boot disks we gave to customers. At that point I thought it was a
bad idea. ;-)
 
V

Vladimir Vassilevsky

Jan 1, 1970
0
Modern OSs like to own the hardware, which makes hacking difficult.

For that reason, I keep the 12-year old computer with Win98 as an OS.
Win95/98/ME allows the direct access to ports with the interrupts disabled.

There are the special drivers for the port hacking in WinNT/2k/XP
(dllportio and such). It works, however the timing jitter is horrible.

I don't know if there are the drivers like that for Vista. I am not
familiar with Vista internal architecture, however somebody told me that
it is very difficult to patch the I/O map there.
I'll leave the company name out of it, but we did a bit banging
solution using the dos found on the windows boot disk. I thought it
was cheesy, but not a particularly bad idea. Somehow a virus got on
the boot disks we gave to customers. At that point I thought it was a
bad idea. ;-)

Finding a floppy drive is a problem in our days. Booting MSDOS from DVD
would be fun though. :)



Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
 
D

Didi

Jan 1, 1970
0
Jim said:
...
MC1488 is for SERIAL ports. Back when I was a "cave-man" I designed
it ;-)

LOL, I as wondering what was wrong with Richs numbering - he clearly
meant the Motorola designation of DAC08, at least this is how I read
it
in the context.
I had to see your post to think on the 1488/9 (good old
friends) ... :).
I believe (15+ years old memory) DAC08 was called MC1408, have not
used
one in a while (but until not so long ago their multiplying ability
was
among the best in the class, now they got outclassed, eventually...).

Dimiter
 
R

Rich Grise

Jan 1, 1970
0
MC1488 is for SERIAL ports. Back when I was a "cave-man" I designed
it ;-)

Yeah - I realized that when I looked up the data sheet. The one I
shouild have been thinking about was MC1408L8, but apparently for
8-bit parallel input these days, the DAC08 is the chip of choice.

In fact, I should have known that - the 1489 is the mating receiver, for
something much like "RS-232"; at one company, my engineer and I were
looking at them for a serial link, but we decided they weren't robust
enough to go on a ship, (as in navy battle cruiser or so), so we designed
the interface(s) with discretes - JANTX2N2222As and JANTX2N2907As. :-}

You could plug those puppies into the wall socket and not blow them up!
;-)

Thanks!
Rich
 
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