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Topic: DAC in arduino DUE (Read 7663 times) previous topic - next topic

shtranka

hi, i wanna know if the DAC in arduino DUE can generate a voltage!! thanks

cmiyc

That's exactly what it is does.

http://arduino.cc/en/Reference/AnalogWrite
Quote

The Arduino Due supports analogWrite() on pins 2 through 13, plus pins DAC0 and DAC1. Unlike the PWM pins, DAC0 and DAC1 are Digital to Analog converters, and act as true analog outputs.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

shtranka

, thnks :) , and the maximum value is???

cmiyc

#3
May 06, 2013, 12:55 am Last Edit: May 06, 2013, 06:40 am by James C4S Reason: 1
Less than 3.3v

Keep in mind it can't source much if any current, so don't expect to power something with.

If you want good answers, explain what you are trying to do.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

shtranka

i want to command a wheel chair. i need to give the main card 2 values, the max one is 3.9v , what can i do now!

tmd3

According to this post - http://arduino.cc/forum/index.php/topic,129765.msg994153.html#msg994153 - the Due's DAC can deliver a voltage between about 0.55 V to about 2.75 V.  The low limit is 1/6 of 3.3 V, and the high limit is 5/6 of 3.3 V.


i want to command a wheel chair. i need to give the main card 2 values, the max one is 3.9v , what can i do now!


You can start here - http://www.eng.yale.edu/ee-labs/morse/compo/sloa058.pdf - and develop an op-amp circuit to add gain and offset to your signal.  Note that you'll need a rail-to-rail op-amp if you intend to power it from a 5 V supply.  If you use a general-purpose op-amp, without the rail-to-rail feature, you'll need a positive voltage of something more than 5 V; if you need to get close to ground, you'll also need a negative supply.

shtranka

and can i use both of channels in the same time ( different values)

DuaneB

Yes, but be very careful what you connect it to, a lot of us have accidentally burned ours.

The opamp suggestion from tmd3 is a good suggestion, without this or a similar buffer between the DAC and your load, your DAC might not last very long - mine didn't

Duane B
rcarduino.blogspot.com

Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

JoeN


Yes, but be very careful what you connect it to, a lot of us have accidentally burned ours.

The opamp suggestion from tmd3 is a good suggestion, without this or a similar buffer between the DAC and your load, your DAC might not last very long - mine didn't

Duane B
rcarduino.blogspot.com




The easiest way to protect a pin is to put a resistor on it so it cannot source too much current.  Whatever the maximum safe current is for that pin, place a resistor in series with it that limits the current to something less than that.
I will never ask you to do anything that I wouldn't do myself.

shtranka

the AOP is a good idea but the values that i will generate are not constant( obstacle avoidance) it means it can change instantly and any direction has its values (exp  to turn right i must give 3.9v and 2.5v)

DuaneB

Your not going to get from 2.7 volts to 3.9 volts with just a resistor for help.

Why do you think an op amp is not going to change value when you ask it to ?

Duane B

rcarduino.blogspot.com
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

shtranka

so 2 op amp are enough to deliver 16 different values automaticlly!!!

shtranka

would you plz give an example of such circuit! because i still don,t have the arduino and i wanna make sure before i buy it. thanks

graynomad

an opamp can "deliver" an almost infinite number of "values", all it does is amplify and/or shift what you give it.

If you give it 16 different levels you will get 16 different levels out of it that may or may not be the same as the inputs depending on how you construct the circuit.

What exactly are these values you need, 16 equally spaced from 2v7 to 3v9?

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

shtranka

i have 8 directions and each one has 2 axis, and i have sensors, so what i need is to run the wheel chair automaticly to avoid obstacles. so it depends on the position of the wheel chair and his next move without any intervention of the user.

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