Hello,
Is my configuration of Timer1 wrong ?
void setup()
{
Serial.begin(9600);
noInterrupts();
// Initialise timer/counter to known value
TCCR1A = 0;
TCCR1A = _BV(COM1A1) | _BV(COM1A0); // Enable D9 OUTPUT
TCCR1A = _BV(WGM11) /*| _BV(WGM10)*/; // Enable pwm to 511
TCCR1B = 0;
TCCR1B = //|
//_BV(WGM13)
//|
//_BV(WGM12)
//;
// Set prescaler (divide by) on the clock ticks for 16MHz clock
/* For Timer 1 the options for are:
* 111 divide by 1024 = 15.625kHz = 64uS
* 110 divide by 256 = 62.5kHz = 16uS
* 101 divide by 126 = 125kHz = 8
* 100 divide by 64 = 250kHZ = 4
* 011 divide by 32 = 500kHz = 2
* 010 divide by 8 = 2MHz = 0.5
* 001 divide by 1 = 16MHz = 0.0625 uS
* 000 timer disabled
*
* the CSnn are the Clock Source prescaler TTCRnB bits we are setting
*/
// TCCR1B = 0;
// TCCR1B = ((1 << CS22) | (1 << CS21) | (1 << CS20));
// or
// TCCR1B |= 0b00000111;
// or
TCCR1B = _BV(CS12) |
_BV(CS11)
//|
//_BV(CS10)
; // Prescaler 62.5khz
// Enable interrupts on overflow by adjusting pins 2:0
// Set the Timer 1 Interrupt Mask Register so that
// we enable to overflow interrupt TOIE1 (Timer 1 Overflow Interrupt Enable)
// AND when the values match two values (comparators OCIE1A & OCIE1B) we
// trigger two further, independent interrupts.
TIMSK1 = ((1 << TOIE1) /*| (1 << OCIE1A) */ /*| (1 << OCIE1B)*/);
OCR1A = 255; // Dutycycle of 50%
pinMode(9, OUTPUT);
interrupts();
}
void loop()
{
// put your main code here, to run repeatedly:
}
ISR(TIMER1_ovf_vect)
{
Serial.println("interrupt");
}
Thanks
The second line overrides the first and the third overrides the second, thus disabling inverted PWM on OC1A.
You can either use:
// Initialise timer/counter to known value
TCCR1A = _BV(COM1A1) | _BV(COM1A0);
TCCR1A |= _BV(WGM11);
or
// Initialise timer/counter to known value
TCCR1A = _BV(COM1A1) | _BV(COM1A0) | _BV(WGM11);
Tried your two solutions but neither works.
The ISR(TIMER1_OVF_vect) is not triggered.
It's ok! my bad,many thanks
I haven't used interrupts yet, but I have read here that printing in an interrupt routine is not a good idea.
It is not a good idea, yes. But for testing, it's a time saver. When the solution will be found, I'll remove all those Serial.print
Where did you get that table from? It is not correct.
Table 16-5. Clock Select Bit Description
CS12
CS11
CS10
Description
0
0
0
No clock source (Timer/Counter stopped).
0
0
1
clkI/O/1 (No prescaling)
0
1
0
clkI/O/8 (From prescaler)
0
1
1
clkI/O/64 (From prescaler)
1
0
0
clkI/O/256 (From prescaler)
1
0
1
clkI/O/1024 (From prescaler)
1
1
0
External clock source on T1 pin. Clock on falling edge.
1
1
1
External clock source on T1 pin. Clock on rising edge.
This means your
selects an external clock source. Your timer will never count up.
Didn't you get a warning message?
In file included from /Users/john/Library/Arduino15/packages/arduino/hardware/avr/1.8.4/cores/arduino/Arduino.h:30:0,
from sketch/sketch_jan25a.ino.cpp:1:
/Users/john/Documents/Arduino/sketch_jan25a/sketch_jan25a.ino: In function 'void TIMER1_ovf_vect()':
/Users/john/Documents/Arduino/sketch_jan25a/sketch_jan25a.ino:65:5: warning: 'TIMER1_ovf_vect' appears to be a misspelled 'signal' handler, missing '__vector' prefix [-Wmisspelled-isr]
ISR(TIMER1_ovf_vect)
^
In function 'TIMER1_ovf_vect':
/Users/john/Documents/Arduino/sketch_jan25a/sketch_jan25a.ino:65:1: warning: 'TIMER1_ovf_vect' appears to be a misspelled 'signal' handler, missing '__vector' prefix [-Wmisspelled-isr]
ISR(TIMER1_ovf_vect)
^
They are using the Timer2 table for Timer1.
Maybe that it will not work ?
Yeah I used the wrong timer table... shame on me
DaveX
January 31, 2022, 4:34pm
11
Did you want it toggling a pin?
You can tell if your configuration of a timer is wrong by printing the control registers and confirming they are configured as intended:
void reportTimer1(void) {
static unsigned long lastReport = 0;
if (millis() - lastReport < 1000) return;
lastReport = millis();
Serial.print("TCCR1A 0xb");
Serial.print(TCCR1A, BIN);
Serial.print(" TCCR1B 0xb");
Serial.print(TCCR1B, BIN);
Serial.print("TCNT1 :");
Serial.print(TCNT1);
Serial.print("OCRA1 :");
Serial.print(OCRA1);
Serial.print("TMSK1 :");
Serial.print(TMSK1);
Serial.println();
}
I'll add that function and put a reportTimer1(); in the setup() or loop().
You should switch your selected solution to #6 .
And where did you get that wrong table comment? It will intermittently mess people up in several different ways, depending on the prescaler they choose.
