iwoloschin 
I'm working with a Teensy2++, which has an AT90USB1287 onboard. Looking at the datasheet, I've got 4 Timers, but it looks like they all use the same prescaler. I assume I can use all 4 timers independently of each other, at the same time, but are there any caveats to watch out for while doing this? I've glanced through Dean's Timer Tutorial, but it doesn't talk about using more than one timer at the same time, and I haven't been able to find much else on the topic.
Thanks!
theusch 
Looking at the datasheet, I've got 4 Timers, but it looks like they all use the same prescaler.
Have you looked at this?
12. Timer/Counter0, Timer/Counter1, and Timer/Counter3 PrescalersTimer/Counter0, 1, and 3 share the same prescaler module, but the Timer/Counters can have
different prescaler settings. The description below applies to all Timer/Counters. Tn is used as a
general name, n = 0, 1 or 3.
Except for rare instances such as Output Compare Modulator (OCM) you can consider AVR8 timers as being independent of each other.
iwoloschin Yeah, I noticed that in the datasheet, but I seem to be running into an issue that when I enable the second timer, the first one gets screwed up.
I'm using TIMER1 (16 Bits) to generate a 1Hz interrupt:
/** Timer 1 - 1 Second Interrupt Generator **/ // Set CTC Mode TCCR1B |= (1 << WGM12); // Set Output Compare Channel A for 1 Hz @ 16 MHz / 256 OCR1A = 62499; // TIMSK1 |= (1 << OCIE1A);
I start/stop that with an interrupt:
ISR(INT7_vect)
{
/* Stopwatch Start/Stop Switch */
TCCR1B ^= (1<<CS12);
}
I'm doing some internal timekeeping and turning that 1Hz pulse into a MM:SS display on a 4 digit 7 segment display. This works great.
Now I'm trying to add in an IR remote control using the NEC encoding technique, which is basically varying pulse lengths to indicate 0/1. Logical solution, set up a second timer to count pulses, along with a Overflow interrupt to monitor a timeout scenario.
/* Set up interrupt pin for the IR Decoder */ DDRD &= (0<<3); PORTD &= (1<<3); EICRA = (1<<ISC31 | 0<<ISC30); EIMSK |= (1<<INT3); /* Set up Timer 0 to count pulse length */ TCCR0A = (0<<COM0A1 | 0<<COM0A0 | 0<<COM0B1 | 0<<COM0B0 | 0<<WGM01 | 0<<WGM00); TCCR0B = (0<<FOC0A | 0<<FOC0B | 0<<WGM02 | 0<<CS02 | 0<< CS01 | 0<<CS00); TCNT0 = 0x00; TIMSK0 |= 1<<TOIE0;
Start/stopping the timer isn't written yet, but would be handled by an interrupt (INT3) where the IR Receiver is plugged into. However, just setting TIMER0 up, or more, the Overflow interrupt, seems to break TIMER1, and I'm not sure why. It's like TIMER1 can never start counting if the TIMER0 Overflow interrupt is enabled.
theusch Do you have an ISR to "catch" the event?
-- Show a complete test program that demonstrates the symptoms
-- Tell how you are testing, what results you expect, and what results you get
-- Try to capture the reset cause and see what it says
I start/stop that with an interrupt:
Code:
ISR(INT7_vect)
{
/* Stopwatch Start/Stop Switch */
TCCR1B ^= (1<<CS12);
}
ChaunceyGardiner
DDRD &= (0<<3); PORTD &= (1<<3);
iwoloschin iwoloschin wrote:
DDRD &= (0<<3); PORTD &= (1<<3);
Those two lines don't make much sense.
That was an error, it's supposed to be input w/ pullup enabled.
Regarding bounce, I know there's bouncing going on, but for what I'm doing, it's fine for now. Eventually the start/stop will be controlled by the remote, which shouldn't exhibit bouncing, but I wanted to make sure the stopwatch worked before I tackled the remote :).
clawson 
That was an error, it's supposed to be input w/ pullup enabled.
DDRD &= ~(1 < 3); PORTD |= (1 << 3);
You missed ~ in the first and used 0 not 1.
You used the wrong operator all together in the second. It should be OR not AND.
If you don't understand why it must be like this go to the Tutorial Forum and read "Bit Manpulation - Programming 101"
ChaunceyGardiner But that would be:DDRD &= ~(1 < 3); PORTD |= (1 << 3);
DDRD &= ~(1 << 3); PORTD |= (1 << 3);
clawson iwoloschin Yup I must learn to type :oops:
It's cool, I'm having the same problems :). At least your's is just on the forums, and not in code...