[Solved]Guru Meditation Error:



  • Hi, when I upload on M5Stack base, the following sketch..

    /* Ultrasonic distance sensor example - Better Version
    
       Paul Carpenter, PC Services
       26-Jan-2017
    
       Update 4-Feb-2017 PC make variables more obvious
       Update 13-May-2017 PC add half bit rounding to distance calculation
    
       Uses HC-SR04 four pin ultrasonic sensor to continuously output distances
       found when in range (every second).
    
       Results WHEN valid output onto serial port at 115,200 baud
    
       Both LEDs ON when program starts and any other time for no start of echo
       received (probably bad wiring or faulty unit) on start up also serial port
       error string
        
       Lights RED Led when No Reading received or out of range
       Lights Yellow LED when too close (less than 5 cm)
       LEDs are connected via 330R or similar resistor other end of LED to GND
    
       Works on principle sound travels at 343.2 m/s in dry STILL air at 20 deg C
    
       So time per cm is 29.137529 micro seconds /cm
    
       For round trip (there and back)  58.275058 micro seconds /cm
    
       In order to reduce code size and execution time values are kept as integers
       and factor of 58 to calculate distances
    */
    
    /* Pin definitions */
    #define echopin     4
    #define trigpin     5
    #define redled      6
    #define yellowled   7
    
    /* time between readings in ms
       On Arduino Mega readings belown 20ms interval could 
       have residual echo issues */
    #define INTERVAL    30
    
    /* Scale factor round trip micro seconds per cm */
    #define SCALE_CM    58
    #define SCALE_CM_ROUND  (SCALE_CM/2)
    
    /* Timeout for distance sensing rather than 1 second in us */
    #define MAX_ECHO    300000
    #define MIN_ECHO    (3 * SCALE_CM)
    
    /* Timeout for start of ECHO pulse being received in us */
    #define MAX_START_ECHO  1000
    
    /* Limits for application ranges in cm */
    #define MIN_RANGE   4
    #define MAX_RANGE   500
    
    #define MAX_ERROR 10
    
    /* calculated distance in centimetres */
    unsigned long distance;
    unsigned int echotime;
    unsigned long next_time, new_time;
    
    
    /* Distance sensor function to get echo time
       Note most ultrasonic distance sensors are only usable beyond 3 cm
       So usable range is 3 * SCALE_CM to MAX_ECHO, therefore anything below
       3 * SCALE_CM should be treated as error
    
       Returns echo time in microseconds
            Maximum MAX_ECHO
            Minimum 3 * SCALE_CM    (minimum usable)
       error codes
            Error   2   Echo HIGH before start
            Error   1   Echo did not start
            Error   0   NO ECHO (Timeout)
    
       Timeout for measurements set by MAX_ECHO
    */
    unsigned long GetEchoTime( )
    {
    unsigned long start_time;
    unsigned long end_time;
    
    /* check Echo if high return error */
    if( digitalRead( echopin ) )
      return( 2 );
      
    /* note start time */
    start_time = micros( );
    
    /* send the trigger pulse */
    digitalWrite( trigpin, HIGH );
    delayMicroseconds( 10 );
    digitalWrite( trigpin, LOW );
    
    /* Set timeout for start of echo pulse */
    end_time = start_time + MAX_START_ECHO;
    
    /* check ECHO pin goes high within MAX_START_ECHO
       if not return error of 1  */
    while( !digitalRead( echopin ) )
       if( micros( ) > end_time )
         return( 1 );
    
    /* Check for Length of echo occurred or timeout */
    start_time = micros( );
    end_time = start_time + MAX_ECHO;
    while( digitalRead( echopin ) )
       if( micros( ) > end_time )
         break;
    end_time = micros( );
         
    /* Return time or timeout   */
    return( ( start_time < end_time ) ? end_time - start_time: 0 );
    }
    
    
    void setup( )
    {
    /* set time from reset */
    next_time = INTERVAL;
    
    Serial.begin( 115200 );
    
    /* Configure pins and ensure trigger is OFF */
    pinMode( trigpin, OUTPUT );
    digitalWrite( trigpin, LOW );
    pinMode( echopin, INPUT );
    
    /* Configure LED drive and both LEDs On at start up */
    pinMode( redled, OUTPUT );
    pinMode( yellowled, OUTPUT );
    digitalWrite( redled, HIGH );
    digitalWrite( yellowled, HIGH );
    
    /* Send signon message */
    Serial.println( F( "PC Services - Better Range test" ) );
    
    /* Do test reading to check if unit connected */
    distance = GetEchoTime( );
    if( distance > 0 && distance <= 10 )
      {
      Serial.println( F( "No unit found - Error = " ) );
      Serial.println( distance );
      }
    }
    
    
    void loop( )
    {
    new_time = millis( );           /* check if to run this time */
    if( new_time >= next_time )
      {
      /* Turn LEDs Off */
      digitalWrite( redled, LOW );
      digitalWrite( yellowled, LOW );
    
      /* Calculate distance */
      echotime = GetEchoTime( );
      /* only scale valid readings 0 is timeout or 1 is no echo
         realistically minimum accurate or physical range is 3cm */
      if( echotime > MAX_ERROR )
        {
        // Valid number covert to cm
        distance = echotime;
        distance += SCALE_CM_ROUND;  // add in half bit rounding  
        distance /= SCALE_CM;
        }
    
      /* catch errors first */
      if( echotime <= MAX_ERROR || distance > MAX_RANGE )
        {
        digitalWrite( redled, HIGH );               // Range error too large
        if( echotime > 0 && echotime <= MAX_ERROR )
          digitalWrite( yellowled, HIGH );          // Light 2nd LED error
        }
      else
        if( distance < MIN_RANGE )
          digitalWrite( yellowled, HIGH );          // Range too close
        else
          Serial.println( int( distance ) );        // In range output distance
    
      next_time = new_time + INTERVAL;       // save next time to run
      }
    }
    

    I got this error... why?

    rst:0x1 (POWERON_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)
    configsip: 0, SPIWP:0xee
    clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
    mode:DIO, clock div:1
    load:0x3fff0018,len:4
    load:0x3fff001c,len:1100
    load:0x40078000,len:9220
    load:0x40080400,len:6300
    entry 0x400806a4
    Guru Meditation Error: Core  1 panic'ed (LoadProhibited). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (Unhandled debug exception)
    Debug exception reason: Stack canary watchpoint triggered (loopTask) 
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstructionGuru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Double exception)
    
    


  • @cepics said in Guru Meditation Error::

    Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled

    Unkown but seeing this pop up a few times on github with those pins.
    Try installing this arduino plugin and see what it says.
    link text

    Where are you getting pins 4, 6, 7 from as they are not broken out anywhere?



  • @ajb2k3 said in Guru Meditation Error::

    Where are you getting pins 4, 6, 7 from as they are not broken out anywhere?

    I'm testing with pins 21 and 22 for the hc-sr04 and no ledconnected....



  • @cepics Shouldn't it then be 21 and 22 defined in the code?
    GPIO 6 and 7 are not broken out.
    I thought that in arduino that pin was also defined as the gpio number.
    21 and 22 are digital pins isn't the echopin analogue?



  • I already use the hc-sr04 on M5stack with this code:

    // defines pins numbers
    const int trigPin = 22;
    const int echoPin = 21;
    // defines variables
    long duration;
    int distance;
    void setup() {
    pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
    pinMode(echoPin, INPUT); // Sets the echoPin as an Input
    Serial.begin(9600); // Starts the serial communication
    }
    void loop() {
    // Clears the trigPin
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    // Sets the trigPin on HIGH state for 10 micro seconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    // Reads the echoPin, returns the sound wave travel time in microseconds
    duration = pulseIn(echoPin, HIGH);
    // Calculating the distance
    distance= duration*0.034/2;
    // Prints the distance on the Serial Monitor
    Serial.print("Distance: ");
    Serial.println(distance);
    }
    

    but I would like to test the "better version" one



  • this code:

    /* Ultrasonic distance sensor example - Better Version
    
       Paul Carpenter, PC Services
       26-Jan-2017
    
       Update 4-Feb-2017 PC make variables more obvious
       Update 13-May-2017 PC add half bit rounding to distance calculation
    
       Uses HC-SR04 four pin ultrasonic sensor to continuously output distances
       found when in range (every second).
    
       Results WHEN valid output onto serial port at 115,200 baud
    
       Both LEDs ON when program starts and any other time for no start of echo
       received (probably bad wiring or faulty unit) on start up also serial port
       error string
        
       Lights RED Led when No Reading received or out of range
       Lights Yellow LED when too close (less than 5 cm)
       LEDs are connected via 330R or similar resistor other end of LED to GND
    
       Works on principle sound travels at 343.2 m/s in dry STILL air at 20 deg C
    
       So time per cm is 29.137529 micro seconds /cm
    
       For round trip (there and back)  58.275058 micro seconds /cm
    
       In order to reduce code size and execution time values are kept as integers
       and factor of 58 to calculate distances
    */
    
    /* Pin definitions */
    #define echopin     21
    #define trigpin     22
    #define redled      6
    #define yellowled   7
    
    /* time between readings in ms
       On Arduino Mega readings belown 20ms interval could 
       have residual echo issues */
    #define INTERVAL    30
    
    /* Scale factor round trip micro seconds per cm */
    #define SCALE_CM    58
    #define SCALE_CM_ROUND  (SCALE_CM/2)
    
    /* Timeout for distance sensing rather than 1 second in us */
    #define MAX_ECHO    300000
    #define MIN_ECHO    (3 * SCALE_CM)
    
    /* Timeout for start of ECHO pulse being received in us */
    #define MAX_START_ECHO  1000
    
    /* Limits for application ranges in cm */
    #define MIN_RANGE   4
    #define MAX_RANGE   500
    
    #define MAX_ERROR 10
    
    /* calculated distance in centimetres */
    unsigned long distance;
    unsigned int echotime;
    unsigned long next_time, new_time;
    
    
    /* Distance sensor function to get echo time
       Note most ultrasonic distance sensors are only usable beyond 3 cm
       So usable range is 3 * SCALE_CM to MAX_ECHO, therefore anything below
       3 * SCALE_CM should be treated as error
    
       Returns echo time in microseconds
            Maximum MAX_ECHO
            Minimum 3 * SCALE_CM    (minimum usable)
       error codes
            Error   2   Echo HIGH before start
            Error   1   Echo did not start
            Error   0   NO ECHO (Timeout)
    
       Timeout for measurements set by MAX_ECHO
    */
    unsigned long GetEchoTime( )
    {
    unsigned long start_time;
    unsigned long end_time;
    
    /* check Echo if high return error */
    if( digitalRead( echopin ) )
      return( 2 );
      
    /* note start time */
    start_time = micros( );
    
    /* send the trigger pulse */
    digitalWrite( trigpin, HIGH );
    delayMicroseconds( 10 );
    digitalWrite( trigpin, LOW );
    
    /* Set timeout for start of echo pulse */
    end_time = start_time + MAX_START_ECHO;
    
    /* check ECHO pin goes high within MAX_START_ECHO
       if not return error of 1  */
    while( !digitalRead( echopin ) )
       if( micros( ) > end_time )
         return( 1 );
    
    /* Check for Length of echo occurred or timeout */
    start_time = micros( );
    end_time = start_time + MAX_ECHO;
    while( digitalRead( echopin ) )
       if( micros( ) > end_time )
         break;
    end_time = micros( );
         
    /* Return time or timeout   */
    return( ( start_time < end_time ) ? end_time - start_time: 0 );
    }
    
    
    void setup( )
    {
    /* set time from reset */
    next_time = INTERVAL;
    
    Serial.begin( 115200 );
    
    /* Configure pins and ensure trigger is OFF */
    pinMode( trigpin, OUTPUT );
    digitalWrite( trigpin, LOW );
    pinMode( echopin, INPUT );
    
    /* Configure LED drive and both LEDs On at start up */
    pinMode( redled, OUTPUT );
    pinMode( yellowled, OUTPUT );
    digitalWrite( redled, HIGH );
    digitalWrite( yellowled, HIGH );
    
    /* Send signon message */
    Serial.println( F( "PC Services - Better Range test" ) );
    
    /* Do test reading to check if unit connected */
    distance = GetEchoTime( );
    if( distance > 0 && distance <= 10 )
      {
      Serial.println( F( "No unit found - Error = " ) );
      Serial.println( distance );
      }
    }
    
    
    void loop( )
    {
    new_time = millis( );           /* check if to run this time */
    if( new_time >= next_time )
      {
      /* Turn LEDs Off */
      digitalWrite( redled, LOW );
      digitalWrite( yellowled, LOW );
    
      /* Calculate distance */
      echotime = GetEchoTime( );
      /* only scale valid readings 0 is timeout or 1 is no echo
         realistically minimum accurate or physical range is 3cm */
      if( echotime > MAX_ERROR )
        {
        // Valid number covert to cm
        distance = echotime;
        distance += SCALE_CM_ROUND;  // add in half bit rounding  
        distance /= SCALE_CM;
        }
    
      /* catch errors first */
      if( echotime <= MAX_ERROR || distance > MAX_RANGE )
        {
        digitalWrite( redled, HIGH );               // Range error too large
        if( echotime > 0 && echotime <= MAX_ERROR )
          digitalWrite( yellowled, HIGH );          // Light 2nd LED error
        }
      else
        if( distance < MIN_RANGE )
          digitalWrite( yellowled, HIGH );          // Range too close
        else
          Serial.println( int( distance ) );        // In range output distance
    
      next_time = new_time + INTERVAL;       // save next time to run
      }
    }
    

    give this error:

    rst:0x1 (POWERON_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT)
    configsip: 0, SPIWP:0xee
    clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
    mode:DIO, clock div:1
    load:0x3fff0018,len:4
    load:0x3fff001c,len:1100
    load:0x40078000,len:9220
    load:0x40080400,len:6300
    entry 0x400806a4
    Guru Meditation Error: Core  1 panic'ed (LoadProhibited). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruction). Exception was unhandled.
    Guru Meditation Error: Core  1 panic'ed (IllegalInstruGuru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Interrupt wdt timeout on CPU1)
    Guru Meditation Error: Core  1 panic'ed (Double exception)
    
    

    tnks



  • @cepics said in Guru Meditation Error::

    #define redled 6
    #define yellowled 7

    you cant use 5 to 11 as they are reserved for flash.

    change the lines to

    //#define redled 6
    //#define yellowled 7
    

    This is the only difference between you working program an non working program.
    Github has a few errors of this type all connected to pins 5-11 and because the

    Guru Meditation Error: Core 1 panic'ed (IllegalInstruction). Exception was unhandled.
    has been triggered, it keeps crashing the Watchdog timer.
    Guru Meditation Error: Core 1 panic'ed (Interrupt wdt timeout on CPU1)



  • tnks a lot!!!

    this one compile & no error in serial monitor

    /* Ultrasonic distance sensor example - Better Version
    
       Paul Carpenter, PC Services
       26-Jan-2017
    
       Update 4-Feb-2017 PC make variables more obvious
       Update 13-May-2017 PC add half bit rounding to distance calculation
    
       Uses HC-SR04 four pin ultrasonic sensor to continuously output distances
       found when in range (every second).
    
       Results WHEN valid output onto serial port at 115,200 baud
    
       Both LEDs ON when program starts and any other time for no start of echo
       received (probably bad wiring or faulty unit) on start up also serial port
       error string
        
       Lights RED Led when No Reading received or out of range
       Lights Yellow LED when too close (less than 5 cm)
       LEDs are connected via 330R or similar resistor other end of LED to GND
    
       Works on principle sound travels at 343.2 m/s in dry STILL air at 20 deg C
    
       So time per cm is 29.137529 micro seconds /cm
    
       For round trip (there and back)  58.275058 micro seconds /cm
    
       In order to reduce code size and execution time values are kept as integers
       and factor of 58 to calculate distances
    */
    
    /* Pin definitions */
    #define echopin     21
    #define trigpin     22
    //#define redled      6
    //#define yellowled   7
    
    /* time between readings in ms
       On Arduino Mega readings belown 20ms interval could 
       have residual echo issues */
    #define INTERVAL    30
    
    /* Scale factor round trip micro seconds per cm */
    #define SCALE_CM    58
    #define SCALE_CM_ROUND  (SCALE_CM/2)
    
    /* Timeout for distance sensing rather than 1 second in us */
    #define MAX_ECHO    300000
    #define MIN_ECHO    (3 * SCALE_CM)
    
    /* Timeout for start of ECHO pulse being received in us */
    #define MAX_START_ECHO  1000
    
    /* Limits for application ranges in cm */
    #define MIN_RANGE   4
    #define MAX_RANGE   500
    
    #define MAX_ERROR 10
    
    /* calculated distance in centimetres */
    unsigned long distance;
    unsigned int echotime;
    unsigned long next_time, new_time;
    
    
    /* Distance sensor function to get echo time
       Note most ultrasonic distance sensors are only usable beyond 3 cm
       So usable range is 3 * SCALE_CM to MAX_ECHO, therefore anything below
       3 * SCALE_CM should be treated as error
    
       Returns echo time in microseconds
            Maximum MAX_ECHO
            Minimum 3 * SCALE_CM    (minimum usable)
       error codes
            Error   2   Echo HIGH before start
            Error   1   Echo did not start
            Error   0   NO ECHO (Timeout)
    
       Timeout for measurements set by MAX_ECHO
    */
    unsigned long GetEchoTime( )
    {
    unsigned long start_time;
    unsigned long end_time;
    
    /* check Echo if high return error */
    if( digitalRead( echopin ) )
      return( 2 );
      
    /* note start time */
    start_time = micros( );
    
    /* send the trigger pulse */
    digitalWrite( trigpin, HIGH );
    delayMicroseconds( 10 );
    digitalWrite( trigpin, LOW );
    
    /* Set timeout for start of echo pulse */
    end_time = start_time + MAX_START_ECHO;
    
    /* check ECHO pin goes high within MAX_START_ECHO
       if not return error of 1  */
    while( !digitalRead( echopin ) )
       if( micros( ) > end_time )
         return( 1 );
    
    /* Check for Length of echo occurred or timeout */
    start_time = micros( );
    end_time = start_time + MAX_ECHO;
    while( digitalRead( echopin ) )
       if( micros( ) > end_time )
         break;
    end_time = micros( );
         
    /* Return time or timeout   */
    return( ( start_time < end_time ) ? end_time - start_time: 0 );
    }
    
    
    void setup( )
    {
    /* set time from reset */
    next_time = INTERVAL;
    
    Serial.begin( 115200 );
    
    /* Configure pins and ensure trigger is OFF */
    pinMode( trigpin, OUTPUT );
    digitalWrite( trigpin, LOW );
    pinMode( echopin, INPUT );
    
    /* Configure LED drive and both LEDs On at start up */
    //pinMode( redled, OUTPUT );
    //pinMode( yellowled, OUTPUT );
    //digitalWrite( redled, HIGH );
    //digitalWrite( yellowled, HIGH );
    
    /* Send signon message */
    Serial.println( F( "PC Services - Better Range test" ) );
    
    /* Do test reading to check if unit connected */
    distance = GetEchoTime( );
    if( distance > 0 && distance <= 10 )
      {
      Serial.println( F( "No unit found - Error = " ) );
      Serial.println( distance );
      }
    }
    
    
    void loop( )
    {
    new_time = millis( );           /* check if to run this time */
    if( new_time >= next_time )
      {
      /* Turn LEDs Off */
    //  digitalWrite( redled, LOW );
     // digitalWrite( yellowled, LOW );
    
      /* Calculate distance */
      echotime = GetEchoTime( );
      /* only scale valid readings 0 is timeout or 1 is no echo
         realistically minimum accurate or physical range is 3cm */
      if( echotime > MAX_ERROR )
        {
        // Valid number covert to cm
        distance = echotime;
        distance += SCALE_CM_ROUND;  // add in half bit rounding  
        distance /= SCALE_CM;
        }
    
      /* catch errors first */
      if( echotime <= MAX_ERROR || distance > MAX_RANGE )
        {
      //  digitalWrite( redled, HIGH );               // Range error too large
        if( echotime > 0 && echotime <= MAX_ERROR )
       //   digitalWrite( yellowled, HIGH ); // Light 2nd LED error
       Serial.println("MAX");
        }
      else
        if( distance < MIN_RANGE )
      //    digitalWrite( yellowled, HIGH ); // Range too close
         Serial.println("MIN");
        else
          Serial.println( int( distance ) );        // In range output distance
    
      next_time = new_time + INTERVAL;       // save next time to run
      }
    }
    

  • M5Stack

    @ajb2k3 Thanks a lot !

    @cepics "A custom ESP-WROOM-32 build without any flash chip added, so the existing GPIO6, GPIO7, GPIO8, GPIO9, GPIO10 and GPIO11 pins can be used to allow us to add a GD25Q127C (or similar) on our external circuit."