EM73201
4-BIT MICRO-CONTROLLER FOR GENERAL PURPOSE PRODUCT
XIN/CLK
XOUT
XIN/CLK
XOUT
Crystal connection
RC connection
CLOCK AND TIMING GENERATOR FUNCTION
The frequency of fc is the oscillation frequency for XIN, XOUT by crystal ( resonator) or for CLK by RC
osc.
When CPU sleeps, the XOUT pin will be in "high" state .
When user chooses RC osc, XOUT pin is no used .
The instruction cycle equal 8 basic clock fc.
1 instructure cycle = 8 / fc
TIMING GENERATOR AND TIME BASE
The timing generator produces the system clock from basic clock pulse which can be normal mode or slow
mode clock.
1 instruction cycle = 8 basic clock pulses
There are 22 stages time base .
Prescaler
Binary counter
1 2 3
4
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
fc
When working in the single clock mode, the timebase clock source is come from fc that is RC oscillation.
Time base provides basic frequency for following function:
1. TBI (time base interrupt) .
2. Timer/counter, internal clock source.
3. Warm-up time for sleep - mode releasing.
TIME BASE INTERRUPT (TBI )
The time base can be used to generate a fixed frequency interrupt . There are 8 kinds of frequencies can be
selected by setting "25"
Single clock mode
P25
3
2
1
0
( initial value 0000 )
0 0 x x: Interrupt disable
0 1 0 0: Interrupt frequency XIN / 210 Hz
0 1 0 1: Interrupt frequency XIN / 211 Hz
0 1 1 0: Interrupt frequency XIN / 212 Hz
0 1 1 1: Interrupt frequency XIN / 213 Hz
1 1 0 0: Interrupt frequency XIN / 29 Hz
1 1 0 1: Interrupt frequency XIN / 28 Hz
1 1 1 0: Interrupt frequency XIN / 215 Hz
1 1 1 1: Interrupt frequency XIN / 217 Hz
1 0 x x: Reserved
* This specification are subject to be changed without notice.
7.20.1999 12
ELAN [ ELAN MICROELECTRONICS CORP ]
