Noob need help output

Using Arduino General Electronics
1

Hello all,

I have a Dac that need to be reset when power on.
I use a Due to control the dac chip.

I use 3.3v on one side of a 2.2k resistor and the other side to the dac reset pin. So the dac see 3.3v and that is correct. But when power on i need to make this low for 0.5 sec before it goes high.
Can i connect it to a output on the Arduino? And write the pin low and then high after 0.5 sec?

BR// Daniel

2

So an external DAC instead of the two internal DAC ports of the DUE ?
Leo..

3

Yes, sorry, it’s an external dac.

4

Why?

We need a lot more info to be able to help you.
Read the "how to post" guidelines.
Leo..

5

Sorry, i will try to explosion more details.

It’s a es9038 dac chip.
I use a Arduino Due to control it with i2c bus.
But chip also has a resetb input. It has to be high to when chip is in use.
But all voltage to chip has to be applied before resetb can go high.
So when start the dac chip resetb must be low then after voltage is ok and stabel then it has to go high.

Sorry if impossible to understand…

BR// Daniel

6

The usual way to deal with a reset pin like that is a resistor as you describe and a capacitor between the pin and 0V, maybe 1μF or so. That way the capacitor holds the pin low for a short time until the resistor has had time to charge it.

7

Quite clear.
An RC circuit, as PerryB described, is commonly used for stand-alone chips.
But since you have an Arduino, why don't you let the Due control that reset pin.
Leo..

8

Thanks.

Yes, a RC circuit has crossed my mind also.
But if i want to use the Due how to do that?
Can i just config a pin (A3?) for an output and then directly to Resetb on the dac chip?
Or do i need a pullup or pulldown?

Reason i wrote pin A3 is that all digital pins are full from LCD and switches. I hope i can use a analog pin for this?

BR// Daniel

9

Yes, write a HIGH to the pin after a certain time has elapsed.
You should use millis() timing for that, not delay().
No pull up/down resistor needed, because Arduino outputs are push pull.

Yes, analogue pins are just digital pins with the added functionality of analogue-in.
digitalWrite (A3, HIGH); // is valid
Make sure A3 is set to OUTPUT with pinMode in setup().
Leo..

10

Thanks all for the help.

BR// Daniel

11

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