MycilaPulseAnalyzer

ESP32 / Arduino Library to analyze pulses from a Zero-Cross Detection circuit and manage the Zero-Cross pulse.

• Features
• Supported ZCD Circuits
• Usage
• IRAM Safety
• Zero-Cross event shift
• Oscilloscope Views
  • Robodyn
  • Zero-Cross Detector from Daniel S
  • BM1Z102FJ chip based ZCD
• Use-Case: Thyristor TRIAC Control
• Use-Case: Know when the AC voltage is positive or negative
• Readings

Features

• Detect Zero-Cross pulse
• Ability to shift the Zero-Cross event (MYCILA_PULSE_ZC_SHIFT_US)
• Filter spurious Zero-Cross events (noise due to voltage detection)
• Online / Offline detection
• Uses only 2 timers
• IRAM safe and supports concurrent flash operations!
• Callbacks for:
  • Zero-Cross,
  • Rising Signal
  • Falling Signal
  • Signal Change (BM1Z102FJ)
• Measurements:
  • Period
  • Minimum Period
  • Maximum Period
  • Frequency
  • Pulse Width
  • Minimum Pulse Width
  • Maximum Pulse Width

Supported ZCD Circuits

• Square short pulse (e.g. Zero-Cross Detector from Daniel)

• Slope pulse (e.g. Robodyn ZCD)

• High precision pulse matching AC wave +/- components based on BM1Z102FJ chip (e.g. AC VOLTAGE ZERO CROSS DETECTOR - note that this one needs an additional optocoupler like TLP2630 or 6N136)

More hardware are supported, as long as they fall into one of these categories above.

Usage

Mycila::PulseAnalyzer pulseAnalyzer;

static void ARDUINO_ISR_ATTR onEdge(Mycila::PulseAnalyzer::Event e, void* arg) {
  if (e == Mycila::PulseAnalyzer::Event::SIGNAL_RISING || e == Mycila::PulseAnalyzer::Event::SIGNAL_FALLING) {
    digitalWrite(PIN_OUTPUT, HIGH);
    delayMicroseconds(OUTPUT_WIDTH_US);
    digitalWrite(PIN_OUTPUT, LOW);
  }
}

static void ARDUINO_ISR_ATTR onZeroCross(void* arg) {
  digitalWrite(PIN_OUTPUT, HIGH);
  delayMicroseconds(OUTPUT_WIDTH_US);
  digitalWrite(PIN_OUTPUT, LOW);
}

void setup() {
  Serial.begin(115200);
  while (!Serial)
    continue;

  pinMode(PIN_OUTPUT, OUTPUT);

  pulseAnalyzer.onEdge(onEdge);
  pulseAnalyzer.onZeroCross(onZeroCross);

  pulseAnalyzer.begin(35);
}

Output:

{"state":0,"period":9994,"period_min":9975,"period_max":10014,"frequency":100.0600357,"width":1168,"width_min":1154,"width_max":1182}
{"state":0,"period":9993,"period_min":9976,"period_max":10018,"frequency":100.0700455,"width":1166,"width_min":1154,"width_max":1180}

IRAM Safety

You can run the app with:

-D CONFIG_ARDUINO_ISR_IRAM=1
-D CONFIG_GPTIMER_ISR_HANDLER_IN_IRAM=1
-D CONFIG_GPTIMER_CTRL_FUNC_IN_IRAM=1
-D CONFIG_GPTIMER_ISR_IRAM_SAFE=1
-D CONFIG_GPIO_CTRL_FUNC_IN_IRAM=1

This will improve interrupt reliability (they will continue working even during flash operation).

MycilaPulse makes use of inline function of HAL layer and ARDUINO_ISR_ATTR to ensure that the interrupt handlers are in IRAM.

You can look at teh examples in the project to see how to use this library with IRAM safety.

Zero-Cross event shift

Compile flag -D MYCILA_PULSE_ZC_SHIFT_US is used to control the shift of the Zero-Cross event.

By default, the value is set to -100 us, which means that the Zero-Cross event is shifted by - 100 us from the middle of the pulse (or start in the case of the BM1Z102FJ chip).

Oscilloscope Views

Here are below some oscilloscope views of 2 ZCD behaviors with a pulse sent from an ESP32 pin to display the received events.

• In yellow: the ZC pulse
• In blue: the output pin pulse of 1 us
• In red: main AC voltage
• Measured in pink: distance between the vertical lines

Robodyn

Here are some views of the Robodyn ZC pulse, when adding a 1 us pulse on each event: rising and falling, and a 1us pulse on the ZC event, with -D MYCILA_PULSE_ZC_SHIFT_US=0.

Here is the same view, but after applying a shift of about 100 us to the ZC event:

Zero-Cross Detector from Daniel S

Here are some views of the ZC pulse, when adding a 1 us pulse on each event: rising and falling, and a 1us pulse on the ZC event with -D MYCILA_PULSE_ZC_SHIFT_US=0.

Here is the same view, but after applying a shift of about 100 us to the ZC event:

BM1Z102FJ chip based ZCD

Oscilloscope view of the BM1Z102FJ chip based ZCD where each pulse match the positive component of the AC voltage.

Oscilloscope view with edge detection activated

Oscilloscope view with default Zero-Cross event with -D MYCILA_PULSE_ZC_SHIFT_US=-100 (shifted by -100 us), which is teh default.

Oscilloscope view with default Zero-Cross event (shifted by -200 us)

Oscilloscope view with default Zero-Cross event (shifted by 200 us)

Use-Case: Thyristor TRIAC Control

You can look at the example in the project how to use this library to control a Thyristor / TRIAC with a zero-cross detection circuit.

• In yellow: the ZC pulse
• In blue: the output pin pulse of 1 us
• In red: main AC voltage
• In pink: current going to the load

Use-Case: Know when the AC voltage is positive or negative

The BM1Z102FJ has a positive pulse when the AC voltage is positive, and a negative pulse when the AC voltage is negative.

Thanks to MycilaPulseAnalyzer, you can know when the AC voltage is positive or negative by using the onEdge callback and check if it is a rising or falling edge.

Readings

Here is a blog post explaining how to use this library, with some oscilloscope screenshots:

https://yasolr.carbou.me/blog/2024-07-31_zero-cross_pulse_detection.