ESP32 DAC about 250µS delay on disable output

Other Hardware LEDs and Multiplexing
1

Hello,

If I disable the output of the (internal) DAC I'll get a delay of about 250µS - on enable there isn't such.. hmm

What I've done:

void loop() {

dac_output_disable(DAC_1);
delay(1);
dac_output_enable(DAC_1);
delay(1);

}

or

void loop() {

CLEAR_PERI_REG_MASK(RTC_IO_PAD_DAC1_REG, RTC_IO_PDAC1_XPD_DAC | RTC_IO_PDAC1_DAC_XPD_FORCE);
delay(1);
SET_PERI_REG_MASK(RTC_IO_PAD_DAC1_REG, RTC_IO_PDAC1_XPD_DAC | RTC_IO_PDAC1_DAC_XPD_FORCE);
delay(1);

}

Results are the same ...

See here

2

If you mean by 'delay' the down-going exponential slope, this looks like a capacitor discharging. Have you tried hooking up a 4k7 resistor to the DAC output and repeating the experiment?

3

Thanks - good idea ! I'll give it a try ...

4

Thanks - it's much more better, but...

I'll explain, what I'm doing to achieve :

The goal is to switch very fast ( about 1µs) the output ON/OFF , to get a (very simple) modulation of the DAC Output.

5

How do you distinguish OFF from ON? If you expect 0V then output just 0 instead of OFF.

6

I meant switching between 0V (OFF) and the actual output voltage from DAC …
I‘m looking for a solution with a minimum of external components :sunglasses:
(Take a look to bitlunis blog abot his AM transmitter … to get an idea)

7

Then do so and do not expect magic from turning off the DAC. Why do you think that OFF will drive the output to some specific value?

8

You‘re right ! My fault :weary:

1 Like
9

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