Serial port malfunktion

Projects Programming
1

I have a Nano and is programming through the USB connector. I copied a sketch from the community and it worked fine. "Analog sampler. Trigger analog samples at a time interval selected by timer1".
This is the start code:
void setup() {
Serial.begin(115200);
delay(200);
Serial.println("AnalogSampler started");
When i compile and load up this it produces a first line as expected: AnalogSampler started .
Then I rewrites the next code to change the mode of using the timer1.
Then the first line of the print will be: Ana?
And there will be no more output.

2

Welcome to the forum

Please post your complete sketch using code tags when you do

3

what is the code within loop() ?

4

This is the changed code:

// Analog sampler.  Trigger analog samples at a time interval selected by Timer1

const uint32_t INTERVAL_MICROSECONDS = 40;  // 25 kHz
const uint32_t CLOCKS_PER_MICROSECOND = F_CPU / 1000000ul;
const uint16_t TIMER1_TOP = 1280; //(INTERVAL_MICROSECONDS * CLOCKS_PER_MICROSECOND) - 1;

const byte MAX_SAMPLE_COUNT = 100;
volatile byte SampleCounter = 0;
volatile uint16_t SampleBuffer[MAX_SAMPLE_COUNT];
volatile uint16_t Comparev = TIMER1_TOP;

void setup() {
  Serial.begin(115200);
  delay(200);
  Serial.println("AnalogSampler started");

  // Set up the ADC to start a conversion when Timer1 overflows
  ADMUX = 0;
  ADCSRA = 0;
  ADCSRB = 0;
  DIDR0 = 0x3e; // only ch0 enabled
  DDRB |= _BV(DDB5);
  
  // Select the AVCC reference and input pin A0
  ADMUX |= _BV(REFS0);

  // Set ADC clock prescale.
  // For full resolution (10 bits) the ADC clock must be
  // lower than 200 kHz.  At the expense of a few
  // LSBs we can crank the ADC clock up to 1 MHz
  // and get 74000 samples per second.

//#if (F_CPU > 8000000ul)
  // On a 16 MHz Arduino use a prescale of 16
  // The next higher available prescale is 128.
  ADCSRA |= _BV(ADPS2) | _BV(ADPS0);  // Prescale = 16 = 1 MHz =500kHZ
//#else
  // On an 8 MHz Arduino use a prescale of 8.
  // The next higher available prescale is 64.
 // ADCSRA |= _BV(ADPS = 1) | _BV(ADPS0);  // Prescale = 8 = 1 MHz
//#endif

  // Select auto-trigger source: Begin Conversion on Timer1 Overflow
  ADCSRB |= _BV(ADTS2) | _BV(ADTS0);  //counter1 compareB match

  // ADC Enable, Auto-trigger enable, Clear interrupt flag, Enable interrupt
  ADCSRA |= _BV(ADEN) | _BV(ADATE) | _BV(ADIF) | _BV(ADIE); 

  // Start Timer1 overflowing every INTERVAL_MICROSECONDS
  TCCR1A = 0;
  TCCR1B = 0;
  TIMSK1 = 0;  // Disable all Timer1 interrupts

  OCR1B = TIMER1_TOP;  // Set INTERVAL_MICROSECONDS

  // Set WGM 14 (0b1110): Fast PWM, TOP in ICR1, TOV1 at TOP
  TCCR1A |= _BV(COM1B0);
  TIMSK1 |= _BV(OCIE1B);
  
  TIFR1 |= _BV(OCF1B);  // Clear any pending Timer1 Overflow

  // Start Timer1 with Prescale=1
  TCCR1B |= _BV(CS10);
}

// ADC Conversion Complete interrupt service routine
ISR(ADC_vect) {
  uint16_t val = ADC;
  Comparev = Comparev + TIMER1_TOP;
  OCR1B = Comparev;
//  TIFR1 |= _BV(OCF1B) | _BV(TOV1);  // Clear the pending Timer1 Overflow Interrupt
  PORTB ^= _BV(PORTB5); //koll på sampleintervall 
  

  if (SampleCounter < MAX_SAMPLE_COUNT) {
    SampleBuffer[SampleCounter++] = val;
  }
}

void loop() {
  if (SampleCounter == MAX_SAMPLE_COUNT) {
    // All samples have been collected.  The ISR won't be doing anything
    // until the SampleCount is reset.

    Serial.print(micros());
    Serial.print(", ");
    Serial.print(SampleBuffer[0]);
    Serial.print(", ");
    Serial.print(SampleBuffer[1]);
    Serial.print(", ");
    Serial.println(SampleBuffer[2]);
    Serial.flush();  // Make sure all the character get sent

    SampleCounter = 0;
  }
}
5

i don't see where "ISR()" is configured as the interrupt.
i didn't think you can pass an argument to an ISR

6

Is not the row
ADCSRB |= _BV(ADTS2) | _BV(ADTS0); //counter1 compareB match
defining the ISR?

7

i don't know.
looks like you're trying to configure a timer interrupt. how does it know what code that you've written needs to be executed

8

ADCSRB is a register to the Analog converter, not the timer1

9

???

10

You can see for yourself by looking up the definition of the 'ISR' macro in interrupt.h.

11

It runs the ISR a few times before it hangs up. I can see it on port B5, only used in the IRS.

12

thanks for answering my question.

13

are the prints taking longer than acquisition of the samples?

14

Where do I get
the 'ISR' macro in interrupt.h. ?

15

If I increase the baud rate to 500000bps, it produces "AnalogSampler ?
and if I use 9600bps it comes out ??

16

You're already using it.

17

I'm using the Aurdino 1.8.19 and dont know where to get the used files .

18

What used files?

19

What did you change? You didn't post the original working code...

20

This is the original that works:

// Analog sampler.  Trigger analog samples at a time interval selected by Timer1

const uint32_t INTERVAL_MICROSECONDS = 40; // 25 kHz
const uint32_t CLOCKS_PER_MICROSECOND = F_CPU / 1000000ul;
const uint16_t TIMER1_TOP = (INTERVAL_MICROSECONDS * CLOCKS_PER_MICROSECOND) - 1;

const byte MAX_SAMPLE_COUNT = 3;
volatile byte SampleCounter = 0;
volatile uint16_t SampleBuffer[MAX_SAMPLE_COUNT];

void setup()
{
  Serial.begin(115200);
  delay(200);
  Serial.println("AnalogSampler started");

  // Set up the ADC to start a conversion when Timer1 overflows
  ADMUX = 0;
  ADCSRA = 0;
  ADCSRB = 0;
  DIDR0 = 0;

  // Select the AVCC reference and input pin A0
  ADMUX |= _BV(REFS0);

  // Set ADC clock prescale.
  // For full resolution (10 bits) the ADC clock must be 
  // lower than 200 kHz.  At the expense of a few 
  // LSBs we can crank the ADC clock up to 1 MHz
  // and get 74000 samples per second.

#if (F_CPU > 8000000ul)
  // On a 16 MHz Arduino use a prescale of 16
  // The next higher available prescale is 128.
  ADCSRA |= _BV(ADPS2) | _BV(ADPS0); // Prescale = 16 = 1 MHz
#else
  // On an 8 MHz Arduino use a prescale of 8.
  // The next higher available prescale is 64.
  ADCSRA |= _BV(ADPS=1) | _BV(ADPS0); // Prescale = 8 = 1 MHz
#endif

  // Select auto-trigger source: Begin Conversion on Timer1 Overflow
  ADCSRB |= _BV(ADTS2) | _BV(ADTS1);

  // ADC Enable, Auto-trigger enable, Clear interrupt flag, Enable interrupt
  ADCSRA |= _BV(ADEN) | _BV(ADATE) | _BV(ADIF) | _BV(ADIE);

  // Start Timer1 overflowing every INTERVAL_MICROSECONDS
  TCCR1A = 0;
  TCCR1B = 0;
  TIMSK1 = 0; // Disable all Timer1 interrupts

  ICR1 = TIMER1_TOP; // Set INTERVAL_MICROSECONDS

  // Set WGM 14 (0b1110): Fast PWM, TOP in ICR1, TOV1 at TOP
  TCCR1A |= _BV(WGM11);
  TCCR1B |= _BV(WGM13) | _BV(WGM12);

  TIFR1 |= _BV(TOV1);  // Clear any pending Timer1 Overflow

  // Start Timer1 with Prescale=1
  TCCR1B |= _BV(CS10);
}

// ADC Conversion Complete interrupt service routine
ISR(ADC_vect)
{
  TIFR1 |= _BV(TOV1);  // Clear the pending Timer1 Overflow Interrupt

  uint16_t val = ADC;

  if (SampleCounter < MAX_SAMPLE_COUNT)
  {
    SampleBuffer[SampleCounter++] = val;
  }
}

void loop()
{
  if (SampleCounter == MAX_SAMPLE_COUNT)
  {
    // All samples have been collected.  The ISR won't be doing anything
    // until the SampleCount is reset.

    Serial.print(micros());
    Serial.print(", ");
    Serial.print(SampleBuffer[0]);
    Serial.print(", ");
    Serial.print(SampleBuffer[1]);
    Serial.print(", ");
    Serial.println(SampleBuffer[2]);
    Serial.flush(); // Make sure all the character get sent

    SampleCounter = 0;
  }
}