Getting Started

Chapter 7: Microcontroller Interrupts and Timers

he Ti gister B, TCCR1B and the Timer/Counter2

re set to start timer1 and timer2 with no

<CS10);

egisters we wait for the TCNT2 and the TCRU2B registers

ter2 Update

usy, T

e ASS

) | (ASSR & 0x04));

it a z

;

LL T TING YET!

r can be a

e start calibrating by running a loop in which you make adjustments to the

terna ernal clock, looping until

t a fl

librate = FALSE;

T mer/Counter1 Control Re
Control Register A, TCCR2A, a
prescaling:

TCCR1B = (1<

TCCR2A = (1<<CS20);

After setting all these r
to be set from temporary memory, by waiting for the Timer/Coun
B CN2UB, and the Timer/Counter2 Update Register Busy,TCCR2A, bits of
th R register to be cleared (p 139 data book).

while((ASSR & 0x01

Wa while for the crystal to stabili e:

Delay(1000)

A HIS AND WE HAVEN’T EVEN STARTED CALIBRA

Getting registers set properly to do much of anything in a microcontrolle
long and frustrating exercise, and another good reason to steal code where
possible.

W
in l oscillator and comparing the results to the ext
you get it right.

Se ag:

unsigned char ca

to terminate the loop when true:

while(!calibrate)

On each pass you do the following: