Thanks! That was very helpful. I will run some test and report back.

Regards,

William

One other thing, in my testing it reveals the timer clock runs at 80Mhz, not the CPU clock of 240Mhz. Why is this?


William

I think my issue was with the timer. Not sure why the first timer is off. I try your code when I get a chance.

This doesn't time correctly, does not trigger at 9600:

timer = timerBegin(3, 1, 1);
timerAttachInterrupt(timer, &sample_isr, 1);
timerAlarmWrite(timer, 13333, true);// 9600 ...

I just read this post about the WiPy2 which is a ESP32 based python dev board. It states a 21.3k sps actual tested rate. So makes me thing the 6k rate is based on firmware, not hardware.

https://forum.pycom.io/topic/170/lopy-w ... formance/8

William

A post on this thread talking about ADC in connection with the ESP-IDF APIs mentions that the max sample frequency is 6KHz ... or a maximum sps of 6000. Do you have a project in mind that needs higher sample rates than that?

I already found my answer in another thread. The other thread was asking ...

The maximum sampling frequency of 6000 times a second can be found here ...

https://esp32.com/viewtopic.php?f=2&t=1075

If I may ask, what kind of project needs to sample an analog input at more than 6000 times a second?

I'm decoding AFSK1200. I take 8 samples per AFSK bit. I have this working ...

Anyone know the MAX ADC sample rate? I'm attempting to sample the ADC at 9600 sps, I'm using the analogRead(); function. Is there a faster way? Or is the ADC just too slow for this sample rate?

Thanks!

William

I'm going to close this topic, as I got my answer elsewhere. I will open a new topic on the ADC sample rate discussion.

Here is an example timer sketch, for others

hw_timer_t * timer = NULL;

void onTimer(){
static unsigned int counter = 1;

Serial.print("onTimer ");
Serial.print(counter ...

Max ADC sample rate has been quoted at 6khz

Where is this documented? Do you have a link? That is a pretty sad rate if true. My whole point of using the ESP32 was so I wouldn't have to use an external ADC, as I currently do on the esp8266.

I would still like to figure out the ISR, as SPI ADC's ...

Are there any examples of timer ISR?

I need to sample the adc a a specified rate (9600 times a sec). I would like to attachinterrupt to an ISR. Here is what I'm doing in the ESP8266. How do I do this in the ESP32?

void timer_init(void) {
timer1_isr_init();
timer1_attachInterrupt(sample_isr ...