I am using Arduino Mega2560, i have used timer2 as interrupt after 2ms on flag overflow, but somehow it works only once. I have used serial monitoring as you can also see and this tells me that timer interrupt is invoked but then interrupt is not invoked again and program control does not go back in the loop also since it displays "13" and "22" only once. At least it should have displayed "22" continously after timer interrupt was called.Can anybody tell me why timer interrupt does not get invoke again and why it does not return to loop after interrupt.?
#include <avr/io.h>
#include <avr/interrupt.h>
int eraser=0; //0=000
ISR(TIMER2_OVF_vect)
{
TIMSK2=0x00;
TCCR2B=0x00;
TCCR2A=0x00;
TCNT2=0;
TIFR2=0x00;
Serial.println(33);
TCNT2= 131; //reset timer count to 125 out of 255.
TCCR2B=0x6; //using a prescaler of 6 to use divisor 256.
TIMSK2=1; //timer2 Interrupt Mask Register. Set TOIE(Timer Overflow Interrupt Enable).
}
void setup()
{
/*Timer0 would not be used as it is used for other functions.
Timer 5(pin D47) for encoder and interrupt 2(pin 21) for encoder.
Timer2 is 8 bit we'll see if it can be used for time interval between two encoder counts.
This leaves us with Timers 1,3,4,5.
Timer 3(5,3,2) and 4(8,7,6) will be used for motors.*/
Serial.begin(9600);
TCCR2B&=eraser;
TCNT2= 131; //reset timer count to 125 out of 255.
TIFR2= 0x00; //timer2 interrupt flag register: Clear Timer Overflow Flag.
TIMSK2=0x01; //timer2 Interrupt Mask Register. Set TOIE(Timer Overflow Interrupt Enable).
TCCR2B=0x6; //using a prescaler of 6 to use divisor 256.
/*
so it takes 62.5ns per tick in a timer and having set
divisor of 256 so it will take 16usecs per inc and setting
timer2 to 125 would make it count 250 times so
time=62.5nsec * 256 * 125=2msec.
clkTn
TCNTn Timer Counter Register
TCCRnA has LSB of WGM(wave generation mode bits)
TCCRnB Timer Counter Control Register: has LSB of CSn2,CSn1,CSn0.*/
}
void loop()
{
Serial.println(1);
while(1)
{
Serial.println(22);
}
}
Have you tried taking the
ISR(TIMER2_OVF_vect)
{
TIMSK2=0x00;
TCCR2B=0x00;
TCCR2A=0x00;
TCNT2=0;
TIFR2=0x00;
Serial.println(33);
TCNT2= 131; //reset timer count to 125 out of 255.
TCCR2B=0x6; //using a prescaler of 6 to use divisor 256.
TIMSK2=1; //timer2 Interrupt Mask Register. Set TOIE(Timer Overflow Interrupt Enable).
}
block and putting some or all of it into the place where you'd like to start the timer again?
setup only runs once, so my guess is you need to start the timer again.
Related
I'm coming back to Arduino after a long hiatus, and I want to get as close to bare metal as possible while still using an Arduino Uno as an ISP. I decided that I'd start by using an ATTiny85 as a frequency counter, using TImer0 to count pulses on the T0 pin:
/*
* ATTiny frequency counter
* Inputs: Frequency source (amplified to square wave) on T0 (ATTiny85 pin 7/PB2)
* 16MHz Crystal (ATTiny85 pins 2,3)
* Outputs: Simple serial (ATTiny85 pin 6/PB1 as clock, 5/PB0 as data)
*
* Algorithm:
* For each 1 second cycle:
* Shift out previously recorded frequency
* Intitalize Timer0OFC to 0
* Initialize Counter0 to 0
* At end of cycle, count how many times Counter0 overflowed
* Store value of Timer0OFC*256 + COunter0 to Frequency
*
* Transmission:
* To generate clock signal:
* Set compare OCR1A to value of TCNT1+1
* On interrupt of TCNT1=OCR1C:
* Set pin 6 low
* Set pin 5 to appropriate data value
* Set pin 6 high
*
*/
#include <avr/interrupt.h>
#include <avr/iotnx5.h>
//Register values
void setupRegisters(void){
//Timer 1: general timing
PLLCSR=0x00; //No PLL action wanted, counter1 recieves 16MHz system clock
TCCR1=0x8B; //Use clear on match, no pwm, no pin, divide by 10, 0b10001011
OCR1C=125; //Will clear on match
OCR1A=255; //Will be used to conduct 15kHz serial output routine
TIMSK=0x16; //enable overflow interruptS, match A interrupt, 0b00010010
TIFR=0x00; //Hardware reset bit 2 on overflow, and bit 4 on match
TCNT1=0x00; //Counter register
//Timer 0: asynchronously counts frequency
GTCCR=0x00; //no halting, 0b00000000
TCCR0A=0x00; //no pin override functionality,0b00000000
TCCR0B=0x08; //Select rising edge on T0 pin, 0b00000111
TCNT0=0x00; //Counter register
//I/O
PORTB=0x01; //Port B data register, 0b00000001
DDRB=0x13; //PB0 and PB1 as output, PB2 as input, 0b00010011
PINB=0x00; //
PCMSK=0x20; //Pin 5 as data, pin 6 as clock,0x0010000
}
//Global variables
//General timing
uint8_t Timer1OFC=0; //Counts overflows of timer 1
//For frequency counting
uint32_t Timer0OFC=0; //Counts overflows of timer 0
uint32_t frequency=0; //Measured frequency
uint8_t counter2=0; //Divide TCNT1 by 125 for 1Hz cycle
//ISRs
ISR(TIMER1_OVF_vect){ //Timer 1 overflow 0x0004
if(Timer1OFC==125){ //Will happen once a second with 16MHz crystal
frequency=(Timer0OFC*256)+(TCNT0); //Total number of pulses in 1 second period
Timer1OFC=0; //To restart output bit counting
Timer0OFC=0;TCNT0=0; //Resets pulse counter
OCR1A=1; //Start counting outbits
}
else{
Timer1OFC++; //increments counter
}
}
ISR(TIMER0_OVF_vect){//Timer 0 Overflow 0x0005
Timer0OFC++; //increments counter
}
ISR(TIMER1_COMPA_vect){//Timer 1 Match A 0x0003
if(OCR1A<=16){ //16-bit output
PORTB=(PORTB&=0xFD)|(frequency>=(1<<15)); //Clock low, shifts msb out to PB0
frequency=frequency<<1; //Shifts so that output bit next cycle is the next digit over
OCR1A++; //Primes, so that it matches the next time Timer 1 increments
PORTB|=1<<1; //Set clock high (PB1)
}
}
void setup() {
setupRegisters();
}
void loop() {
//Almost everything is handled by interrupts, lol
}
However, when I go to compile, I get the following error message:
wiring.c.o (symbol from plugin): In function `__vector_5':
(.text+0x0): multiple definition of `__vector_5'
C:\Users\pikec\AppData\Local\Temp\arduino_build_54376\sketch\ATTiny_Frequency_counter.ino.cpp.o (symbol from plugin):(.text+0x0): first defined here
collect2.exe: error: ld returned 1 exit status
exit status 1
Error compiling for board ATtiny25/45/85.
What else is utilizing timer0? Do I have any options if I want to reconfigure timer0 without a more sophisticated programmer?
This is because something already declares/uses TIMER0_OVF_vect, that is the fifth interrupt vector in Attiny85.
Likely you already have ISR(TIMER0_OVF_vect) { ... } smacked somewhere by a library or something. Comment the ISR(TIMER0_OVF_vect) { ... } code from your sample and it will compile just fine. Use another timer until you track down the culprit.
I suspect USI/TWI implementations already use that interrupt.
This page has some answers: https://arduino.stackexchange.com/questions/44855/arduino-core-structure-and-timer-usage
Timer 0 = timing and delay functions, using the TIMER0_OVF interrupt, and fast PWM at 980 Hz on pins 5 and 6 (PD5 and PD6)
Timer 1 = phase-correct PWM at 490 Hz on pins 9 and 10 (PB1 and PB2)
Timer 2 = phase-correct PWM at 490 Hz on pins 3 and 11 (PD3 and PB3)
Trying to understand timing / dimming and interrupts using an Arduino Uno (or any other AVR) is being made very difficult by a serious lack of example code. Having found a sketch that starts from zero and ramps up the brightness, I have tried to adapt the code to prevent the continuous loop which occurs when the 16-bit register overflows.
The attached sketch starts up from zero light output and increases over a period of time - currently using the delay() function.
Attempting to adapt the code to prevent the loop from starting the entire process again and to allow the led to remain at the "top" brightness output for x (variable) number of hours has proved to be most elusive. As one of the contributors have noted this area of coding is one of the most difficult to master.
Any advice or guidance which will put me in the right direction will be most appreciated.
...
//fade over 65535 steps
// 16 bit PWM on any pin
// Example uses built in LED on pin 13 (PORTB bit 5)
// https://forum.arduino.cc/index.php?topic=348170.0
void setup() {
pinMode(13, OUTPUT);
cli(); // Disable all interrupts
TCCR1A = 0; // Clear all flags in control register A
TCCR1B = 0; // Clear all flags in control register B
TCNT1 = 0; // Zero timer 1 count
OCR1A = 32768; // Preload compare match register (50% duty cycle)
// No prescaler
//TCCR1B |= _BV(CS12);
//TCCR1B |= _BV(CS11);
TCCR1B |= _BV(CS10);
TIMSK1 |= _BV(OCIE1A); // Enable timer compare interrupt
TIMSK1 |= _BV(TOIE1); // Enable timer overflow interrupt
sei(); // enable all interrupts
}
void loop() {
for (unsigned int x = 1; x < 65535; x++) {
//cli();
OCR1A = x;
//sei();
delay(20);
}
}
ISR(TIMER1_OVF_vect) { // Timer1 overflow interrupt service routine
PORTB |= _BV(PORTB5); // Turn LED (pin 13) on
}
ISR(TIMER1_COMPA_vect) { // Timer1 compare interrupt service routine
PORTB &= ~_BV(PORTB5); // Turn LED off
}
...
I am writing a program for an nRF52 based board using the Redbear Arduino Library. Effectively treating my board as a BLE Nano 2.
I have a timer that ticks every x milliseconds, for example 50ms.
Inside that timer I would like to read data from an I2C sensor and add the reading to a buffer.
I am aware that by default, when inside the timer ISR, interrupts are disabled. I would like to know how to briefly re-enable the I2C interrupt, and get the sensor reading, then disable the interrupts again.
The interval between sensor readings is critical, and I don't just want to set a flag in the timer ISR as I don't know how long it will be before that flag is checked.
Please can someone instruct me on how to breifly enable the I2C interrupts from within a timer ISR?
I have experimented with:
__disable_irq();
__enable_irq();
NVIC_EnableIRQ(SPI0_TWI0_IRQn);
NRF_TWI0->INTENSET = 1;
No joy with any of these, I understand that some of them only work from certain locations in software, so were not functioning correctly within an ISR.
void setup() {
// put your setup code here, to run once
NVIC_SetPriority (TIMER0_IRQn, 2);
NVIC_SetPriority (TIMER1_IRQn, 2);
NVIC_SetPriority (TIMER2_IRQn, 2);
NVIC_SetPriority (SPI0_TWI0_IRQn, 3);
NVIC_SetPriority (SPI1_TWI1_IRQn, 3);
Serial.begin(9600);
Serial.println("Start ");
Serial.print("Priority of TWI0: ");
Serial.println(NVIC_GetPriority (SPI0_TWI0_IRQn));
Serial.println(NVIC_GetPriority (SPI1_TWI1_IRQn));
Serial.print("Priority of Ticker: ");
Serial.println(NVIC_GetPriority (TIMER0_IRQn));
Serial.println(NVIC_GetPriority (TIMER1_IRQn));
Serial.println(NVIC_GetPriority (TIMER2_IRQn));
Wire.begin();
__disable_irq();
__enable_irq();
ticker1s.attach(task_handle, 1);
Wire.requestFrom(0x02,6);
}
void task_handle(void) {
__enable_irq();
Serial.println("Task handle ");
Serial.println("-IRQ enable status: ");
Serial.println(NVIC_GetEnableIRQ(SPI0_TWI0_IRQn));
Serial.println(NVIC_GetEnableIRQ(SPI1_TWI1_IRQn));
NVIC_EnableIRQ(SPI0_TWI0_IRQn);
NRF_TWI0->INTENSET = 1;
NVIC_EnableIRQ(SPI1_TWI1_IRQn);
NRF_TWI1->INTENSET = 1;
Serial.println("-IRQ enable status: ");
Serial.println(NVIC_GetEnableIRQ (SPI0_TWI0_IRQn));
Serial.println(NVIC_GetEnableIRQ (SPI1_TWI1_IRQn));
delay(1000);
Wire.requestFrom(0x02,6);
}
By default, interrupts are not disabled in ISRs on Cortex-M, but rather interrupts are pre-empted based on the priorities set in NVIC (hence the "Nested" part of NVIC). This means that you should simply enable the I2C interrupt as you usually do, and then set the priority using NVIC_SetPriority(IRQn, priority).
Note however that priority numbers are ordered in reverse, so a priority of 0 would pre-empt a priority of say 6. In this case you would set the Timer interrupt priorities to say 1 and the I2C interrupt to 0.
When I try to receive the USART signal with my Silicon Labs CP210x USB to UART Bridge. The only thing I receive is:
<0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0><0> etc
I got the right settings selected: baud rate: 9600 data bits: 8 parity: none stop bits: 1
I use a ATmega128A3U. The test_LED (see code below) on port E pin 0 is working. I used a oscilloscope to check the uart signal. See picture here: http://imgur.com/dPxkdZ6
Does someone know a solution for this?
Does anyone know how to fix a framing error? (My UART software is giving this error)
CODE:
#define F_CPU (32000000UL) // CPU clock speed
#include <avr/io.h>
#include <util/delay.h>
void USARTF0_init() {
USARTF0_BAUDCTRLB = 0; //BSCALE is 0
USARTF0_BAUDCTRLA = 0xCF; //BSEL is 207
USARTF0_CTRLA = 0; //Disable interrupts
USARTF0_CTRLC = USART_CHSIZE_8BIT_gc; //8 data bits, no parity and 1 stop bit
USARTF0_CTRLB = USART_TXEN_bm | USART_RXEN_bm; // //Enable receive,transmit and high speed mode
PORTF_OUTSET = PIN3_bm; // Port F pin 3 as TX
PORTF_DIRSET = PIN3_bm; // TX pin as output
PORTF_OUTCLR = PIN2_bm; // Port F pin 2 as RX
PORTF_DIRCLR = PIN2_bm; // RX pin as input
}
void sendChar(char c) {
while( !(USARTF0_STATUS & USART_DREIF_bm) ); //Wait until DATA buffer is empty
USARTF0_DATA = c;
}
void sendString(char *text) {
while(*text) {
sendChar(*text++);
}
}
int main(void) {
USARTF0_init();
PORTE.DIRSET = PIN0_bm; // make port E pin 0 output (test_LED)
while(1)
{
_delay_ms(10);
sendString("Hello World!\n\r");
PORTE.OUTTGL = PIN0_bm; // test_LED Toggle
}
}
Code source: http://morf.lv/modules.php?name=tutorials&lasit=29
To recap the discussion, so it can useful to someone later.
If you have an oscilloscope, capture a trace for a simple test case, as #DrOctorooi has done with "#~00":
He has marked start and stop bits, and also the data bits (for serial/UART they're least-significant first)
This confirms that UART somehow works.
One should also confirm the voltage levels. 0-3.2V looks about right.
And the time base. On the captured trace it appears 1 bit takes 1.625ms, which means a baudrate of around 615. That's quite far from expected 9600. In fact, that's around 16 times slower.
Since the error has to do with time, the immediate questions are the MCU clock and UART clock dividers (and on more complex devices, and intermediate dividers and clocks).
It turns out the dividers were meant for the 32MHz clock, but this MCU has a clock of 2MHz when it comes out of reset (16 times slower, as we have seen above). Solution was to recalculate the dividers.
I'm trying to play a tone while changing something on an LCD display. I've searched around and tried protothreads, but it seems that the delay still blocks the program. I've also tried removing the delay altogether, but it skipped everything except the last note. Is there a way to play a tone without using delay? (millis perhaps?)
Sample tone sequence:
//Beats per Minute
#define BPM 250
//Constants, try not to touch, touch anyways.
#define Q 60000/BPM //Quarter note
#define W 4*Q //Whole note
#define H 2*Q //Half note
#define E Q/2 //Eigth note
#define S Q/4 //Sixteenth note
void toneFunction()
{
tone(tonePin,C5,Q);
delay(1+W);
tone(tonePin,C5,Q);
delay(1+W);
tone(tonePin,C5,Q);
delay(1+W);
tone(tonePin,C6,W);
}
You can set up a timer and put note changing logic into an interrupt service routine (ISR).
Each X milliseconds, the timer will reset and interrupt your main loop. The ISR will run and pick the next note and call the tone function. After exiting the ISR, the program continues from the point it was interrupted.
I have attached a code I used in one of my projects. The timer will interrupt the main loop every 50ms (20 Hz), therfore you will have to put your own numbers in OCR1A and the pre-scaler. Please read more about timer interrupt in arduino so that you will understand how to do it (for example here: http://www.instructables.com/id/Arduino-Timer-Interrupts/step2/Structuring-Timer-Interrupts/). You can also see the example at the end of this page (http://playground.arduino.cc/Code/Timer1) for a more user friendly way of doing this.
setup() {
....
/* Set timer1 interrupt to 20Hz */
cli();//stop interrupts
TCCR1A = 0;// set entire TCCR1A register to 0
TCCR1B = 0;// same for TCCR1B
TCNT1 = 0;//initialize counter value to 0
OCR1A = 781; // approximately 20Hz
TCCR1B |= (1 << WGM12);// turn on CTC mode
TCCR1B |= (1 << CS12) | (1 << CS10); // 1024 presxaler
TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt
sei();//allow interrupts
}
...
ISR(TIMER1_COMPA_vect){
// pick next note
}