ESP8266/NodeMCU zero cross dimmer crasht

[significant]

Op basis van o.a.:
https://www.instructables...el-Wireless-Light-Dimmer/
https://circuits4you.com/...266-timer-ticker-example/

probeer ik een licht dimmer te maken op NodeMCU. Een en ander gaat goed, behalve de timer die om de x microseconde moet triggeren.

Onderstaande code werkt en loopt niet vast, pas ik de waarde van de trigger naar het gewenste getal aan (28 --> +/- 100 microseconde, zie instructables link) dan crasht de code met een Exception "IllegalInstructionCause"
https://arduino-esp8266.r...est/exception_causes.html

Op Github thread wordt gesuggereerd "core_esp8266_timer.c" aan te passen met toevoeging van

code:

 ICACHE_RAM_ATTR

voor de functie die vanuit de code worden aangeroepen.
https://github.com/esp8266/Arduino/issues/2083
Ook dit werkt niet.

TL;DR waarom crasht het programa als ik de juiste timing instel, d.w.z. 28 ipv 2800?

C:

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include <WebSocketsServer.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <Hash.h>
#include <Ticker.h> 
#include "hw_timer.h"

#include "FS.h"

#define GATE        15
#define SYNC        13
#define PIN_LED     16

#define STEP_TIME 100  //STEP_TIME: 1/(2*frequency*NumLvls)* 10^6 

ESP8266WiFiMulti WiFiMulti;

ESP8266WebServer server (80);
WebSocketsServer webSocket = WebSocketsServer(81);

const char* ssid     = "NEWTON"; // Your ssid
const char* password = "t6A5EB57AK"; // Your Password

String html_home;

uint8_t status;
uint8_t speed;

volatile int i=0;               
volatile boolean zero_cross=0;  


void  ICACHE_RAM_ATTR dim_check() {   

  digitalWrite(PIN_LED, !digitalRead(PIN_LED));
  //Serial.println(millis());                
  if(zero_cross == true) {              
    if(status == 1){
      if(i>=speed + 4) {                     
        digitalWrite(GATE, LOW); // turn on light       
        i=0;  // reset time step counter                         
        zero_cross = false; //reset zero cross detection
      } 
      else {
        i++; // increment time step counter                     
      }
    }                                
  }
  wdt_reset();                                 
} 

void zero_cross_detect() {    
  if(status == 1){
    digitalWrite(GATE, HIGH);      
  }
  zero_cross = true;
}

void webSocketEvent(uint8_t num, WStype_t type, uint8_t * payload, size_t lenght) {
    switch(type) {
        case WStype_DISCONNECTED:
          Serial.printf("[%u] Disconnected!\n", num);
          break;
        case WStype_CONNECTED: {
          IPAddress ip = webSocket.remoteIP(num);
          Serial.printf("[%u] Connected from %d.%d.%d.%d url: %s\n", num, ip[0], ip[1], ip[2], ip[3], payload);

          // send message to client
          webSocket.sendTXT(num, "Connected");
          }
          break;
        case WStype_TEXT:
            Serial.printf("[%u] get Text: %s\n", num, payload);

            if(payload[0] == '#') {
                uint32_t cmdMessage = (uint32_t) strtol((const char *) &payload[1], NULL, 16);

                status = ((cmdMessage >> 8) & 0xFF);
                speed = ((cmdMessage >> 0) & 0xFF);

                speed = ((speed)>(95)?(95):(speed));
                speed = ((speed)<(5)?(5):(speed));
                
                Serial.printf("Status: %d  speed: %d\n", status, speed);
                
                if ( status == 0 )  {
                  digitalWrite(GATE, status);
                }   
            }
            break;
    }

}

void prepareFile(){   
  Serial.println("Prepare file system");
  SPIFFS.begin();
  
  File file = SPIFFS.open("/home.html", "r");
  if (!file) {
    Serial.println("file open failed");  
  }else{
    Serial.println("file open success");

  html_home = "";
  while (file.available()) {
    String line = file.readStringUntil('\n');
    html_home += line + "\n";
  }
  file.close();
  }
}

void setup() {
  speed = 50;
  status = 1;
  
  Serial.begin(115200);
  Serial.println();

  for(uint8_t t = 4; t > 0; t--) {
      Serial.printf("[SETUP] BOOT WAIT %d...\n", t);
      Serial.flush();
      delay(1000);
  }

  pinMode(GATE, OUTPUT);
  pinMode(SYNC, INPUT);
  pinMode(PIN_LED, OUTPUT);

  digitalWrite(GATE, 0);
     
  prepareFile();
  // Connect to WiFi network
  WiFi.mode(WIFI_STA);
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.println(WiFi.localIP());

  // start webSocket server
  webSocket.begin();
  webSocket.onEvent(webSocketEvent);

  if(MDNS.begin("esp8266")) {
      Serial.println("MDNS responder started");
  }

  // handle index
  server.on("/", []() {
      // send home.html
      server.send(200, "text/html", html_home);
  });

  server.begin();

  // Add service to MDNS
  MDNS.addService("http", "tcp", 80);
  MDNS.addService("ws", "tcp", 81);

  Serial.printf("Server Start\n");
  
  //timer_init();
  attachInterrupt(SYNC, zero_cross_detect, RISING);

  timer1_disable();
  timer1_attachInterrupt(dim_check);
  timer1_isr_init();
  timer1_enable(TIM_DIV256, TIM_EDGE, TIM_LOOP);
  timer1_write(2800);

  digitalWrite(PIN_LED, LOW);

  //Set up ESP watchdog
  ESP.wdtDisable();
  ESP.wdtEnable(WDTO_8S);

}

void loop() {
    webSocket.loop();
    server.handleClient();
}

[farlane]

Just a wild guess, gebaseerd op https://github.com/esp826...266/core_esp8266_timer.c:

timer1_attachInterrupt(...) zet interrupts al aan, terwijl er nog geen algemene handler is toegewezen met timer1_isr_init(...). Draai die statements eens om.