Search found 5 matches

by thassan
Thu Dec 08, 2022 12:14 pm
Forum: ESP-IDF
Topic: ESP32 DAC producing popping noise on the speaker
Replies: 3
Views: 3290

ESP32 DAC producing popping noise on the speaker

On ESP32's DAC, I am producing cosine waves of frequencies between 20KHz - 30KHz over a period of 1000ms . After 1000ms, the wave generation is stopped. Furthermore, after every 50ms , the wave frequency is randomly changed between the specified range of 20KHz - 30KHz using a timer callback function...
by thassan
Wed Nov 23, 2022 9:29 am
Forum: ESP-IDF
Topic: Strange DAC behavior at certain frequency step values
Replies: 7
Views: 2897

Re: Strange DAC behavior at certain frequency step values

Aliasing actually works a bit more complicated than that... it's very likely that the waveform you see at 8.3 and 30KHz actually also aren't correct (because the frequencies still are higher than the sample frequency) but just happen to look correct as the intersection of the measured and the sampl...
by thassan
Wed Nov 23, 2022 7:40 am
Forum: ESP-IDF
Topic: Strange DAC behavior at certain frequency step values
Replies: 7
Views: 2897

Re: Strange DAC behavior at certain frequency step values

Then it's likely an aliasing issue: your scopes sample rate and the output frequency align in such a way that the scope happens to take a sample every time the sine that is output is at the same value, and as such the scope shows a flat line rather than the actual signal. If your oscilloscope has s...
by thassan
Tue Nov 22, 2022 7:56 am
Forum: ESP-IDF
Topic: Strange DAC behavior at certain frequency step values
Replies: 7
Views: 2897

Re: Strange DAC behavior at certain frequency step values

Are you sure your scopes sample rate isn't simply aliasing with the frequency you output? As in, if you zoom in, does the 'behaviour' change? Yes. If I run the program with oscilloscope 'zoomed in' (for the glitchy values), I see normal cosine wave. Here's the wave I see for frequency-step '216' : ...
by thassan
Mon Nov 21, 2022 11:32 am
Forum: ESP-IDF
Topic: Strange DAC behavior at certain frequency step values
Replies: 7
Views: 2897

Strange DAC behavior at certain frequency step values

Greetings ! The issue is that I am getting very low frequency (7-10Hz) cosine waves for certain frequency-step values given to DAC control register (SENS_SAR_DAC_CTRL1_REG) . I am expecting frequencies of around 20KHz and 25KHz on those frequency-step points. I am using a modified version of DAC Cos...