Well if you haven't changed the fuses from the factory setting, then it's using the internal 8MHz RC oscillator divided by eight, so the CPU clock is 1MHz.
I wrote this using WinAVR. I don't currently have the HLT core installed, but I did test it with Arduino Tiny and it worked (although I imagine it stepped all over its millis() function in the process, ha!). I think it should work with HLT, but
. Just copy the entire code below into a new sketch, wire an LED to pin 3 (on the DIP package, I assume you're using a DIP?) and see if it blinks on for a second, then off for a second.
If that works, then you only need about the last 30 lines of code as indicated by the comments, try adding those into your sketch. In your setup() function, replace "Timer1.initialize(10000);" and "Timer1.attachInterrupt(screenUpdate);" with "setupTimer1(screenUpdate);".
This is pretty much quick-and-dirty code for a very specific purpose, based on how I understood the requirement. Let me know how (if) it works for you!
//Example for Arduino forum.
//Use ATtiny85 Timer/Counter1 to call a function every 10ms.
//In setup(), call setupTimer1() and pass it the name of your function which will
//run as part of the interrupt service routine (ISR) every 10ms. This function must take no
//arguments, return nothing, and should run as quickly as possible. The delay() and millis()
//functions will not work while the ISR is running and so should be avoided.
//Works with 1MHz or 8MHz system clock (others may be possible, but I got lazy).
//
//In this example, the myISR() function simply turns an LED on for a second, then off for a second.
//Connect the LED to DIP pin 3 (PB4).
//
//Jack Christensen 18Oct2011
//
//Scotchware License: If we meet some day, and you think this is worth it, you can buy me a scotch.
#include <avr/io.h>
#include <avr/interrupt.h>
//function prototypes
void setupTimer1(void (*isrPointer)(void));
void setup(void);
void loop(void);
void myISR(void);
#define LED PORTB4 //connect LED to this pin
#ifndef ARDUINO //main() function not required in Arduino environment
int main(void) {
setup();
for(;;) {loop();}
return 0;
}
#endif
void setup(void) {
DDRB |= _BV(LED); //set the LED pin as an output
setupTimer1(myISR); //set timer1 up to call myISR every 10ms
}
void loop(void) {
}
void myISR() { //this function will be called every 10ms
static uint8_t myCounter;
if (++myCounter == 100) { //has a second elapsed?
myCounter = 0;
PINB |= _BV(LED); //toggle the LED
}
}
//Copy code from here down, AND uncomment the following line and move it near the top of your sketch BEFORE the setup() function.
//void setupTimer1(void (*isrPointer)(void)); //function prototype for setupTimer1()
void (*userISR)(void); //pointer to the user's ISR
void setupTimer1(void (*isrPointer)(void)) {
userISR = isrPointer; //save the pointer to the user's ISR
//set timer1 up to generate an interrupt every millisecond
TCCR1 |= _BV(CTC1); //clear timer1 when it matches the value in OCR1C
TIMSK |= _BV(OCIE1A); //enable interrupt when OCR1A matches the timer value
sei(); //enable global interrupts
OCR1A = 124; //set the match value for interrupt
OCR1C = 124; //and the same match value to clear the timer
#if F_CPU == 1000000 //1MHz system clock
TCCR1 |= _BV(CS12); //set prescaler to divide by 8 (this starts the timer)
#elif F_CPU == 8000000 //8MHz system clock
TCCR1 |= _BV(CS12) | _BV(CS11) | _BV(CS10); //set prescaler to divide by 64 (this starts the timer)
#else
Clock must be 1MHz or 8MHz! //Error, only 1MHz or 8MHz clock (F_CPU) supported.
#endif
}
ISR(TIMER1_COMPA_vect) { //handles the Timer1 Compare Match A interrupt
static uint8_t interruptCount;
if (++interruptCount == 10) { //have there been 10 interrupts? (i.e. 10ms)
interruptCount = 0; //yes, reset the counter
userISR(); //and call the user's ISR
}
}
