Sonsivri
 
*
Welcome, Guest. Please login or register.
Did you miss your activation email?
December 09, 2016, 08:15:25 20:15


Login with username, password and session length


Pages: [1]
Print
Author Topic: Good cheap 12 bit DAC  (Read 2461 times)
0 Members and 1 Guest are viewing this topic.
mabd
Junior Member
**
Offline Offline

Posts: 71

Thank You
-Given: 13
-Receive: 16


« on: March 18, 2008, 02:35:10 14:35 »

Hi;

I am looking for some good cheap DAC serial and parallel
any advice, suggestion
thank you.
Logged
mayler
Junior Member
**
 Muted
Offline Offline

Posts: 68

Thank You
-Given: 14
-Receive: 13


Roger that!


WWW
« Reply #1 on: March 18, 2008, 09:24:09 21:24 »

There are some PICs with A/D who have 12 bits of precision.
Logged

Computer Engineer.
Digital IC Designer - Cadence certified.
caveman508
Junior Member
**
Offline Offline

Posts: 41

Thank You
-Given: 12
-Receive: 6

READ, REAd, REad, Read


« Reply #2 on: March 19, 2008, 02:16:29 02:16 »

I use the 18F4423, It has all of the toys and a 12 bit DAC
Logged
maddoc
Newbie
*
Offline Offline

Posts: 32

Thank You
-Given: 49
-Receive: 14


« Reply #3 on: March 19, 2008, 09:39:13 09:39 »

I had good results in the past using Microchips TC132x series. TC1322 is a 12-bit DAC using SMBus/I2C. You should be able to buy it for around 2$ (US). Good luck!

Sorry mayler and caveman, but mabd asked for a DAC not ADC.
Logged
caveman508
Junior Member
**
Offline Offline

Posts: 41

Thank You
-Given: 12
-Receive: 6

READ, REAd, REad, Read


« Reply #4 on: March 19, 2008, 03:33:25 15:33 »

Sorry All,

That is what we all get when we don't read, confused and mis-informed.

But I might add, now that I am here:
If you have a PWM module (most are 10 bit though), or create one based on a timer, you get a DAC for free.  The code for the hardware PWM is very easy, the code for any number of bits wide is fairly simple.

Now that is what I call a "Good cheap 12 bit DAC".

Sorry to not have seen DAC, my mind just saw ADC, I have been working with them for a long time.

Caveman
Logged
mabd
Junior Member
**
Offline Offline

Posts: 71

Thank You
-Given: 13
-Receive: 16


« Reply #5 on: March 19, 2008, 05:48:27 17:48 »

PWM+resistor+cap (Low pass Filter) is not enough for me, I have used it for sometime.


Thanks maddoc, I will look for the datasheet.

Isn't there something "popular"

** caveman508   18F4423:
Mah!!! interesting, I know 16C681/2 (6 or 7 booh!!!)
and I think 16F785

But 18F with DAC; interesting
Logged
caveman508
Junior Member
**
Offline Offline

Posts: 41

Thank You
-Given: 12
-Receive: 6

READ, REAd, REad, Read


« Reply #6 on: March 19, 2008, 07:32:35 19:32 »

mabd,

As maddoc pointed out, I read your request wrong, I have never seen a PIC with a built in DAC.

Quote
PWM+resistor+cap (Low pass Filter) is not enough for me, I have used it for sometime.

Why is that simple approach not "enough" for you?

Caveman
Logged
maddoc
Newbie
*
Offline Offline

Posts: 32

Thank You
-Given: 49
-Receive: 14


« Reply #7 on: March 19, 2008, 08:03:09 20:03 »

Mabd, here is the datasheet: http://www.ortodoxism.ro/datasheets/microchip/21388b.pdf
Those parts are simple, robust DACs. I always used them without problems.

Caveman, if for example one wants 100k samples /second then PWM simply won't cut it, you must set the PWM for at least 4 times the sample frequency (8 times is even better) so you won't have hiss in the signal. No PIC can produce such a high frequency PWM at more than 4bits precision. This is a clear case for DAC's.

Let's assume you want to output a 16kHz wave file. You must put the PWM for 4x that frequency to still have 8 bits precision, but you will still have a high pitch hiss and if you filter that out than you loose the upper freq. part of that wave file. If you try 8 or 10 times that frequency you won't get 8bits precision anymore. Now just think of a 96kHz wave file...

On the other hand if you use a 8bit DAC then all your problems are solved and you just have to pump those 8bits at the required frequency to get a clear and crisp sound.

(a pic 18F with a built in DAC would be great! somebody should hear this at microchip - how hard would it be to put an 8 or even 16bit register and 16 or 32 100k and 200k resistors in there, tied to a pin?)
« Last Edit: March 19, 2008, 08:07:59 20:07 by maddoc » Logged
adrian
Newbie
*
Offline Offline

Posts: 30

Thank You
-Given: 27
-Receive: 14


« Reply #8 on: March 20, 2008, 05:14:25 05:14 »

There are several ways to construct a DAC. The PWM RC circuit is only suitable for low frequency application. typically 0-100Hz.
Hopefully you have a lot of extra pins. R2R Ladder is quite easy to construct but it used up lots of your i/o pins. It has good accuracy and the cheapest that i can think off without using extra external part. Use 12pins instead of 8pins.Resistors value should be changed. Buffer the output (opamp/transistor) incase drive current is too low. Hope this helps. Smiley

More detail information here;
DA Conversion Using PWM and R-2R Ladders to Generate Sine and DTMF Waveforms
http://ww1.microchip.com/downloads/en/AppNotes/00655a.pdf
Logged
jestanoff
Junior Member
**
Offline Offline

Posts: 46

Thank You
-Given: 23
-Receive: 18



WWW
« Reply #9 on: March 20, 2008, 08:10:17 08:10 »

Look for DAC7512 from Texas Instruments. It is very cheap and fast serial 12-bits DAC.
http://www.ti.com/lit/gpn/dac7512
Logged
mabd
Junior Member
**
Offline Offline

Posts: 71

Thank You
-Given: 13
-Receive: 16


« Reply #10 on: March 20, 2008, 04:52:13 16:52 »

thank you everybody, you are very nice.
a small gift to everybody
Read about
The Man Behind the Microchip: Robert Noyce and the Invention of Silicon Valley
http://www.sonsivri.com/forum/index.php?topic=11586.0
Logged
mayler
Junior Member
**
 Muted
Offline Offline

Posts: 68

Thank You
-Given: 14
-Receive: 13


Roger that!


WWW
« Reply #11 on: March 21, 2008, 03:51:03 03:51 »

Sorry for my mistake... I read ADC   Smiley

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1155,C1005,P1509

I think it maybe can attend your necessity.
There are cheaper models, but with other caractheristics...
Logged

Computer Engineer.
Digital IC Designer - Cadence certified.
Pages: [1]
Print
Jump to:  


DISCLAIMER
WE DONT HOST ANY ILLEGAL FILES ON THE SERVER
USE CONTACT US TO REPORT ILLEGAL FILES
ADMINISTRATORS CANNOT BE HELD RESPONSIBLE FOR USERS POSTS AND LINKS

... Copyright 2003-2999 Sonsivri.to ...
Powered by SMF 1.1.18 | SMF © 2006-2009, Simple Machines LLC | HarzeM Dilber MC