EM78P447S
OTP ROM
4.8 CODE Option Register
The EM78P447S has one CODE option word that is not a part of the normal program memory. The option bits cannot
be accessed during normal program execution.
Bit12
MS
Bit11
/ENWDT
Bit10 Bit9 Bit8
CLK CS HLP HLP TYPE
Bit7
Bit6
Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
-
-
-
-
-
-
• Bit 12 (MS):Oscillator type selection.
0: RC type
1: XTAL type(XTAL1 and XTAL2)
• Bit 11 (/ENWDT): Watchdog timer enable bit.
0: Enable
1: Disable
• Bit 10 (CLK): Instruction period option bit.
0: two oscillator periods.
1: four oscillator periods.
Refer to the section on Instruction Set.
• Bit 9 (CS): Code Security Bit
0: Security On
1: Security Off
• Bit 8 (HLF): XTAL frequency selection
0: XTAL2 type (low frequency, 32.768KHz)
1: XTAL1 type (high frequency)
This bit will affect system oscillation only when Bit12(MS) is “1”. When MS is”0”, HLF must be “0”.
<Note>: The transient point of system frequency between HXT and LXY is around 400 KHz.
• Bit 7 (HLP): Power selection.
0: Low power
1: High power
• Bit 6(TYPE): Type selection for EM78P447SA or B.
0: EM78P447SB
1: EM78P447SA
• Bit 5 and Bit4: Reserved.
The bit5 set to “1” all the time.
The bit4 set to “0” all the time.
• Bit 3~0 : Customer’s ID code
This specification is subject to change without prior notice.
27
06.25.2003 (V1.1)
ELAN [ ELAN MICROELECTRONICS CORP ]
