HT47C20L View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT47C20L' PDF : 55 Pages View PDF
HT47C20L
Mask Option
The following shows many kinds of mask options in the HT47C20L. All these options should be defined in order to en-
sure proper system functioning.
No.
Mask Option
1 WDT enable or 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. One time” means that
2 the ²CLR WDT² can clear the WDT. ²Two times² means that only if both of the ²CLR WDT1² and ²CLR
WDT2² have been executed, then WDT can be cleared.
3
Time base time-out period selection. The time base time-out period ranges from fS/212 to fS/215. ²fS² stands
for the 32768Hz frequency.
Buzzer output frequency selection. There are eight types of frequency signals for the buzzer output:
4
fS/22~fS/29. ²fS² stands for the 32768Hz.
5
Wake-up selection. This option defines the wake-up function activity. External I/O pins (PA NMOS output
only) all have the capability to wake-up the chip from a halt mode by a following edge.
6
Pull high selection. This option is to decide whether the pull high resistance is viable or not on the low nibble
of the PA.
PA CMOS or NMOS selection.
7
The structure of the low nibble of the PA can be selected as CMOS or NMOS. When CMOS is selected, the
related pins can only be used for output operations. When NMOS is selected, the related pins can be used
for input or output operations.
I/O pins share with other function selection.
8 PA0/BZ, PA1/BZ: PA0 and PA1 can be set as I/O pins or buzzer outputs.
PA3/PFD: PA3 can be set as I/O pins or PFD output.
LCD common selection. There are three types of selection: 2 common (1/2 duty, 1/2 bias) 3 common (1/3
9 duty, 1/2 bias) or 4 common (1/4 duty, 1/3 bias). If the 4 common is selected, the segment output pin
²SEG19/COM3² will be set as a common output ²COM3².
The low voltage reset and the low voltage detector enable or disable selection.
10 There are three types of selection. The low voltage reset and the voltage detector are both enabled or both
disabled or the low voltage reset is disabled but the voltage low detector is enabled.
11
LCD on or LCD off at the halt mode selection.
The LCD can be enable or disable at the halt mode by mask option.
Rev. 2.30
27
December 2, 2005
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