XIAO ESP32C2 ~5 ms pause/freeze every 2 seconds

[dead5ailor]

Hello,

i have a problem with the XIAO ESP32c3. In my setup, I use a AS5600 absolute angle sensor that is connected to the ESP32 via I2C. I use this sensor to measure the angle of a motor shaft. The motor is controlled with a DRV8833 motor driver an I use PWM to set the motor speed.

Now to the problem: The senor readings have jumps repeatable jumps. Between every two jumps there is exactly 2000 ms time passing.
To show this behavior, I used PuTTY to log the serial output. In the next figure you see the plot of the angle measurement with the jump in angle value:

(As a new user I’m only allowed to upload one picture per post, so i will continue in the next post)

[dead5ailor]

But not only the angle measurement shows a jump, also if i plot millis() there is a jump every 2 seconds:

In this figure you can see that the millis() on the Y-axis jump about 5 ms between measurement point 2311 and measurement point 2312 whereas normally the difference is only 1 ms.

(As a new user I’m only allowed to upload one picture per post, so i will continue in the next post)

[dead5ailor]

Here you see millis() again on the y-axis over the measuring points but more zoomed out. At every blue circle a jump is happening. By comparing the Y-values, it’s clear that there is always 2000 ms between to jumps:

First, I thought it was a problem with the used AS5600 library and I opened an issue on GitHub (Link). I recommend reading the issue to see the tests I did to solve the problem. But in short I tried:

• Changing baud rate → no difference
• Trying another AS5600 board → no difference
• Using the Seeed AS5600 library → no difference
• calling yield() in void loop() → no difference
• calling delay(1) in void loop() → no difference
• Setting i2c clock to 1000000 → no difference
• Measuring at motor standstill → no difference

Then i tested the same code on an ESP8266 and the problem was not present anymore.
Is there a function that stops/blocks/pauses/interrupts/etc. the XIAO ESP32 every 2 seconds and how can I solve my problem?

Thank you for your help!

Here is the sketch is use:

#include <Wire.h>
#include "AS5600.h"



AS5600 as5600;

//PWM
//https://www.upesy.com/blogs/tutorials/how-to-use-pwm-on-esp32-with-examples

const int in1 = D1; // Steuer-Pins für den drv8833
const int in2 = D2;
const int frequency = 1000; // 5000 Hz
const int pwmChannel1 = 1;
const int pwmChannel2 = 2;
const int resolution = 8; // 8-bit resolution


int motorSpeed = 200;

int ang = 0;
int raw_ang = 0;
int old_ang = 0;
int revs = 0;
int abs_ang = 0;

int counter = 1;

int t_start = 0;
int t_end = 0;

int t = 0;


void setup() {
Serial.begin(115200);
Serial.println("DRV Test");

Wire.begin();
Wire.setClock(400000);

ledcSetup(pwmChannel1, frequency, resolution);
ledcSetup(pwmChannel2, frequency, resolution);

ledcAttachPin(in1, pwmChannel1);
ledcAttachPin(in2, pwmChannel2);

as5600.begin();
as5600.setDirection(AS5600_CLOCK_WISE);  // default, just be explicit
int b = as5600.isConnected();
Serial.print("Connect: ");
Serial.println(b);

ang = as5600.rawAngle();
ang = ang * AS5600_RAW_TO_DEGREES;
old_ang = ang;

}

void loop() {

  ledcWrite(pwmChannel1, motorSpeed);
  ledcWrite(pwmChannel2, 0);
 
  raw_ang = as5600.rawAngle();

  ang = raw_ang * AS5600_RAW_TO_DEGREES;

  if (old_ang > 340 && ang < 20)
    {
      revs++;
    }
   if (old_ang < 20 && ang > 340)
    {
      revs--;
    }

  abs_ang = revs * 360 + ang;
  if (counter == 3)
    {Serial.print(ang);
    Serial.print("\t");
    Serial.print(raw_ang);
    Serial.print("\t");
    Serial.print(abs_ang);
    Serial.print("\t");
    Serial.print(revs);
    Serial.print("\t");
    t = millis();
    Serial.print(t);
    Serial.print("\t");
    Serial.print(as5600.getAngularSpeed());
    Serial.println();
    counter = 0;
    }
  counter++;
  old_ang = ang;

}

[PJ_Glasso]

Hi , Very interesting issue , I would like to know Have you tried changing the SPEED of the motor?
How do you use the Interrupt? Only the PWM function.
TIA
GL

[dead5ailor]

Some more tests i did in the meantime:

• changing motor speed from 200 to 100
• testing another program to log the serial data
• disabling ledcSetup, ledcAttachPin and ledcWrite so that no PWM signal is created and the motor is at standstill
  Nothing changed, the problem is still there.

@PJ_Glasso

How do you use the Interrupt?

What do you mean by that? I only use the code posted in post 3

[dead5ailor]

I just tried with another XIAO ESP32C2 board - still the same problem every 2000 milliseconds.

[Ariel_The_Enginner]

Hey,
I’m facing trouble with the AS5600 and XIAO ESP32C3.
I did the next connections:
SDA - GPIO 6
SCL - GPIO 7
GND - GND
VDD - 5V

No matter what code I’m uploading, nothing work and I cant read any value.
Can someone help me please?