HT49R50 Holtek Semiconductor Inc, HT49R50 Datasheet - Page 29

• Manufacturer Part Number: HT49R50
• Description: 8-Bit Microcontroller
• Manufacturer: Holtek Semiconductor Inc

Mask option
The following shows 18 kinds of mask options
in the HT49C50. All these options should be de-
Register Bit No. Label Read/Write Reset
RTCC
(09H)
No.
1
2
3
4
5
6
7
8
9
OSC type selection. This option is to decide if an RC or Crystal oscillator is chosen as sys-
tem clock.
WDT Clock source selection. RTC and Time Base. There are three types of selection: sys-
tem clock/4 or RTC OSC or WDT OSC.
WDT enable/disable selection. WDT can be enabled or disabled by mask option.
CLR WDT times selection. This option defines how to clear the WDT by instruction. ²One
time² means that the ²CLR WDT² can clear the WDT. ²Two times² means only if both of
the ²CLR WDT1² and ²CLR WDT2² have been executed, the WDT can be cleared.
Time Base time-out period selection. The Time Base time-out period ranges from
clock/2
uzzer output frequency selection. There are eight types of frequency signals for buzzer
output: Clock/2
Wake-up selection. This option defines the wake-up capability. External I/O pins (PA
only) all have the capability to wake-up the chip from a HALT by a falling edge.
Pull-high selection. This option is to decide whether the pull-high resistance is visible or
not on the PA0~PA3 and PC. (PB and PA4~PA7 are always pull-high)
PA0~PA3 and PC CMOS or NMOS selection.
The structure of PA0~PA3 and PC each 4 bits can be selected as CMOS or NMOS individ-
ually. When the CMOS is selected, the related pins only can be used for output opera-
tions. When the NMOS is selected, the related pins can be used for input or output
operations. (PA4~PA7 are always NMOS)
0~2
5~7
3
4
12
to clock/2
QOSC
RT0
RT1
RT2
¾
¾
2
~Clock/2
15
. ²Clock² means the clock source selected by mask option.
R/W
R/W
¾
¾
9
. ²Clock² means the clock source selected by mask option.
RTCC register
¾
¾
0
0
Mask Option
29
8 to 1 multiplexer control inputs to select the
real time clock prescaler output
Unused bits, this bit must dear to ²0²
Control the RTC OSC to oscillate quickly
²0² enable
²1² disable
Unused bits, read as ²0²
fined in order to ensure proper system function-
ing.
Function
August 18, 1999
HT49C50