Searching \ for '[PIC]Microcontrollers with D/A function' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/ios.htm?key=d%2Fa
Search entire site for: 'Microcontrollers with D/A function'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]Microcontrollers with D/A function'
2010\03\08@154756 by Jason Hsu

picon face
I have used PIC microcontrollers that measure the voltage of a signal
at a particular instant in time with an A/D converter that converts
the value into 0-255 (8-bit) or 0-1023 (10-bit).

What PIC microcontrollers do the opposite - convert a value (0-255 or
0-1023) into a 0-5V voltage output?  What examples of completed
projects that use the D/A are there?

--
Jason Hsu
http://www.jasonhsu.com/swrwatt.html
http://www.jasonhsu.com/swrwatt-c.txt
http://www.jasonhsu.com/swrwatt-asm.txt

2010\03\08@161239 by Steve Smith

flavicon
face
Use a PWM into a low pass filter you just need the capture module.

Steve

-----Original Message-----
From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] On Behalf Of
Jason Hsu
Sent: 08 March 2010 20:48
To: Microcontroller discussion list - Public.
Subject: [PIC]Microcontrollers with D/A function

I have used PIC microcontrollers that measure the voltage of a signal
at a particular instant in time with an A/D converter that converts
the value into 0-255 (8-bit) or 0-1023 (10-bit).

What PIC microcontrollers do the opposite - convert a value (0-255 or
0-1023) into a 0-5V voltage output?  What examples of completed
projects that use the D/A are there?

--
Jason Hsu
http://www.jasonhsu.com/swrwatt.html
http://www.jasonhsu.com/swrwatt-c.txt
http://www.jasonhsu.com/swrwatt-asm.txt

2010\03\08@162254 by ivp

face picon face
> What PIC microcontrollers do the opposite - convert a value (0-255 or
> 0-1023) into a 0-5V voltage output?

Jason,

There are PICs with D/A modules (eg the 16-bit families)

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2629&param=en533465

where you'll find links to application notes, for example ADCPM

but a D/A can be made from any PIC with a little h/w. PWM
into an integrater for example. This can be as simple as an RC filter

> What examples of completed projects that use the D/A are there?

Depends what resolution you're looking for. 8-bit ? 10 ? 12 ? 16 ?

http://www.romanblack.com/picsound.htm

http://www.embedinc.com/pic/hal.htm



2010\03\08@162546 by Brendan Gillatt

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Jason Hsu wrote:
> I have used PIC microcontrollers that measure the voltage of a signal
> at a particular instant in time with an A/D converter that converts
> the value into 0-255 (8-bit) or 0-1023 (10-bit).
>
> What PIC microcontrollers do the opposite - convert a value (0-255 or
> 0-1023) into a 0-5V voltage output?  What examples of completed
> projects that use the D/A are there?
>

Selecting the "DAC" option in the Microchip "MAPS" tool (which I highly
recommend over the web based chip selection system) lists 6 of the
dsPIC33F devices that have a true hardware DAC.

As Steve suggested, a CCP module with a lowpass filter will work in many
situations. Other options are bit-banged PWM--again with a lowpass
filter--or an external DAC chip.

- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (MingW32)

iD8DBQFLlWtUHEhZ5Ws5poERAlsAAJ9o4IN5DmZb4oCtKg4Gp+NPZgzObwCfdLo2
XvF/Vb3GDLPYTw/vlM6sl+w=
=fzf+
-----END PGP SIGNATURE-----

2010\03\08@162839 by Jan-Erik Soderholm

face picon face
On 2010-03-08 21:47, Jason Hsu wrote:

> What PIC microcontrollers do the opposite - convert a value (0-255 or
> 0-1023) into a 0-5V voltage output?

16-bit PICs : 15.

8 or 32 bit PICs, don't know. None as it seems...

2010\03\08@172542 by Dario Greggio

face picon face
Jan-Erik Soderholm ha scritto:
> On 2010-03-08 21:47, Jason Hsu wrote:
>
>> What PIC microcontrollers do the opposite - convert a value (0-255 or
>> 0-1023) into a 0-5V voltage output?
>
> 16-bit PICs : 15.
>
> 8 or 32 bit PICs, don't know. None as it seems...
>



18F2620 et similar can use the Comparator VRef as a 4bit DAC output.


--

Ciao, Dario
--
Cyberdyne

2010\03\08@220308 by William \Chops\ Westfield

face picon face

On Mar 8, 2010, at 1:25 PM, Brendan Gillatt wrote:

> Other options are bit-banged PWM--again with a lowpass
> filter--or an external DAC chip.

With the PICs relatively strong output drivers, you can also think  
about using a set of resistors attached to some digital pins...

BillW

2010\03\09@023741 by Russell McMahon

face picon face
As Steve notes, you can use PWM. Depending on what response time you want
and how much external hardware you can tolerate you may be able to get N
channels of D2A using software PWM.

If you have an interrupt 'tick' you can write extremely simple and low code
overhead multi channel PWM routines.  Worst case cycle time is N interrupts
where you want N steps. eg for 8 bit PWM = 256 steps you want 256 IRQs worst
case. If the IRQ is 10 uS then the PWM cycle is 2.566 mS. If the IRQ rate is
1 mS the PWM cycle rate (frame length) = 0.256s etc. Simple RC filtering
will allow reasonably smooth DC if the filter time constant is >> the frame
period. Got 2.56 mS frame rate you may use say about 256 mS filtering. For a
slower frame rate the filter settling time gets too long for many purposes
(but not all).

However, by implementing a few poles of active low pass filtering can get a
vastly improved DC response time. By using a jellybeam transistor in emitter
follower mode and 2 x R and 2 x C you can get 2 poles and 3 poles with 3R
and 3C. Plus maybe a few more R in each case for real world stuff. Add
another stage and you can get 4 or 5 poles. The precision of the required
components rises  IF you want a genuine classic filter implementation , but
odds are a 4 pile try hard Bessel filter will work extremely well.
Even 2 or 3 poles is much better than a straight RC.

Using emitter followers you get some DC offset issues. If you want good
precision a cheap op amp per stage makes things much better.

If you can use a timer module you can get > or >> 1 Mhz bit rates and
filtering gets much easier and simple RC may do in many cases. Adding an
opamp unity gain buffer is usually a good idea.


          Russell



On 9 March 2010 09:47, Jason Hsu <jhsu802701spamKILLspamgmail.com> wrote:

{Quote hidden}

>  -

2010\03\09@125111 by Jon Chandler

flavicon
face
Here's an example using PWM, coded in Swordfish Basic.  It shows the circuit
and results:

http://digital-diy.com/swordfish/73-swordfish-tutorial-digital-to-analogue-conversion-dac-via-pwm.html





Here is a reference to an EDN Design Note using resistor ladders.  This
design is great because it only uses 6 values of resistors and can be 4
bits, 8 bits, 12 bits, etc.


digital-diy.com/forum/viewtopic.php?f=3&t=382

2010\03\11@121546 by M.L.

flavicon
face
On Mon, Mar 8, 2010 at 11:03 PM, William "Chops" Westfield
<.....westfwKILLspamspam.....mac.com> wrote:
>
> On Mar 8, 2010, at 1:25 PM, Brendan Gillatt wrote:
>
>> Other options are bit-banged PWM--again with a lowpass
>> filter--or an external DAC chip.
>
> With the PICs relatively strong output drivers, you can also think
> about using a set of resistors attached to some digital pins...
>
> BillW
>

I did this to make a 40kHz arbitrary waveform generator for an
ultrasound application. It worked pretty well. I matched the resistors
so that the linearity was pretty good. Follow it up with a lowpass
filter and you're good to go.

--
Martin K.

More... (looser matching)
- Last day of these posts
- In 2010 , 2011 only
- Today
- New search...