HT45R35V Holtek Semiconductor Inc., HT45R35V Datasheet - Page 13

• Manufacturer Part Number: HT45R35V
• Description: C/r To F Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

Interrupts, occurring in the interval between the rising
edges of two consecutive T2 pulses, will be serviced on
the latter of the two T2 pulses, if the corresponding inter-
rupts are enabled. In the case of simultaneous requests
the following table shows the priority that is applied.
These can be masked by resetting the EMI bit.
The EMI, EEI0, EEI1, ETI and ERCOCI bits are all used
to control the enable/disable status of interrupts. These
bits prevent the requested interrupt from being serviced.
Once the interrupt request flags, TF, RCOCF, EIF1 and
EIF0, are all set, they remain in the INTC1 or INTC0 reg-
isters respectively until the interrupts are serviced or
cleared by a software instruction.
It is recommended that a program does not use the
rupts often occur in an unpredictable manner or need to
be serviced immediately in some applications. If only one
stack is left and enabling the interrupt is not well con-
trolled, the original control sequence may be damaged
once the CALL is executed in the interrupt subroutine.
Oscillator Configuration
Various oscillator options offer the user a wide range of
functions according to their various application require-
ments. Two types of system clocks can be selected
while various clock source options for the Watchdog
Timer are provided for maximum flexibility. All oscillator
options are selected through the configuration options.
The two methods of generating the system clock are:
One of these two methods must be selected using the
configuration options.
More information regarding the oscillator is located in
Application Note HA0075E on the Holtek website.
External Crystal/Resonator Oscillator
The simple connection of a crystal across OSC1 and
OSC2 will create the necessary phase shift and feed-
back for oscillation, and will normally not require exter-
nal capacitors. However, for some crystals and most
Rev. 1.00
CALL subroutine within the interrupt subroutine. Inter-
External Interrupt 0
External Interrupt 1
Timer/Event Counter Overflow
External RC Oscillation
Converter Interrupt
External crystal/resonator oscillator
External
Interrupt Source
RC oscillator
Interrupt Priority
Priority
1
2
3
4
Vector
0CH
04H
08H
10H
13
resonator types, to ensure oscillation and accurate fre-
quency generation, it may be necessary to add two
small value external capacitors, C1 and C2. The exact
values of C1 and C2 should be selected in consultation
with the crystal or resonator manufacturer s specifica-
tion. The external parallel feedback resistor, Rp, is nor-
mally not required but in some cases may be needed to
assist with oscillation start up.
Crystal Frequency
12MHz
8MHz
4MHz
1MHz
Note: 1. C1 and C2 values are for guidance only.
Resonator Frequency
3.58MHz
1MHz
455kHz
Note: C1 and C2 values are for guidance only.
Internal Ca, Cb, Rf Typical Values @ 5V, 25°C
Resonator Recommended Capacitor Values
Crystal Recommended Capacitor Values
TBD
Oscillator Internal Component Values
Ca
Crystal Oscillator C1 and C2 Values
2. CL is the crystal manufacturer specified
load capacitor value.
Crystal/Resonator Oscillator
Resonator C1 and C2 Values
TBD
Cb
TBD
TBD
TBD
TBD
C1
TBD
TBD
TBD
C1
TBD
TBD
TBD
TBD
C2
January 15, 2009
HT45R35V
TBD
Rf
TBD
TBD
TBD
C2
TBD
TBD
TBD
TBD
CL