ht82m72e Holtek Semiconductor Inc., ht82m72e Datasheet - Page 21

• Manufacturer Part Number: ht82m72e
• Description: Ht82m72e/ht82m72a -- Rf One Channel Mouse 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Note:
Oscillator
There are three oscillator circuits contained within the
device. The first is the system oscillator which utilities an
external crystal and the second and third is the Watch-
dog timer and Built_in RC timer. Both of Watchdog timer
and Built_in RC timer are fully integrated and require no
external components.
The PC.3 bit is used to select the system clock source. If
PC.3 is set high then the system clock will be sourced
from the external crystal otherwise it will be sourced from
the Built_in RC timer. Bit PB.7 is used to indicate whether
the external crystal or Built_in RC is in operation.
Built_in RC Timer Oscillator
The Built_in RC timer oscillator is a fully self-contained free
running on-chip RC oscillator with a typical frequency of
1MHz at 5V requiring no external components.
System Clock Configurations
The system clock is generated using an external crystal.
The simple connection of a crystal across OSC1 and
OSC2 will create the necessary phase shift and feed-
back for oscillation, without requiring external capaci-
tors. However, for some crystal types and frequencies,
to ensure oscillation, it may be necessary to add two
Rev. 1.20
PCL
MP
ACC
TBLP
TBLH
STATUS
INTC
TMRL
TMRH
TMRC
PA
PAC
PB
PBC
PC
PCC
PD
PDC
PE
Register
* means warm reset
- not implemented
u means unchanged
x means unknown
(Power-on)
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
00-0 1000
xxxx 1111
1xxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
-xxx xxxx
--00 xxxx
xxxx xxxx
Reset
000H
(Normal Operation)
WDT time-out
1uuu uuuu
uuuu uuuu
uuuu uuuu
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-uuu uuuu
-000 0000
00-0 1000
xxxx 1111
--1u uuuu
xxxx xxxx
xxxx xxxx
000H
21
(Normal Operation)
small value capacitors, C1 and C2. Using a ceramic res-
onator will usually require two small value capacitors,
C1 and C2, to be connected as shown for oscillation to
occur. The values of C1 and C2 should be selected in
consultation with the crystal or resonator manufacturer's
specification. In most applications, resistor R1 is not re-
quired, however for those applications where the LVR
function is not used, R1 may be necessary to ensure the
oscillator stops running when VDD falls below its operat-
ing range.
More information regarding the oscillator is located in
Application Note HA0075E on the Holtek website.
Watchdog Timer Oscillator
The WDT oscillator is a fully self-contained free running
on-chip RC oscillator with a typical period of 65 s at 5V
requiring no external components. When the device en-
RES Reset
1uuu uuuu
uuuu uuuu
uuuu uuuu
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-uuu uuuu
-000 0000
00-0 1000
xxxx 1111
--uu uuuu
xxxx xxxx
xxxx xxxx
000H
Crystal/Ceramic Oscillator
HT82M72E/HT82M72A
RES Reset
1uuu uuuu
uuuu uuuu
uuuu uuuu
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-uuu uuuu
-000 0000
00-0 1000
xxxx 1111
--00 uuuu
xxxx xxxx
xxxx xxxx
(HALT)
000H
WDT Time-out
1uuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
-uuu uuuu
-uuu uuuu
uu-u uuuu
--11 uuuu
May 22, 2008
(HALT)*
000H