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.
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!
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.
I expect the O.P. is a hardware design guy and someone else will (eventually) do the software, hence he's trying to shorten his own schedule since all he needs to do is verify he wired up the hardware the right way and the software guy can write the "real" code.
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.
"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.
On Wed, 02 Apr 2008 14:36:56 -0700, DL top-posted: ...
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!
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 Consultant
MC1488 is for SERIAL ports. Back when I was a "cave-man" I designed it ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
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.
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. ;-)
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.
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
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...).
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! ;-)
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.