em78p156n ELAN Microelectronics Corp, em78p156n Datasheet - Page 30

• Manufacturer Part Number: em78p156n
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

This specification is subject to change without prior notice.
1. Code Option Register (Word 0)
• Bit 12 ¡B 11 ¡B 10 ¡B 9:Not used.
Reserved.
The bit set to “1” all the time.
• Bit 8 (CLKS): Instruction period option bit.
0: two oscillator periods.
1: four oscillator periods.
Refer to the section on Instruction Set.
• Bit 7(ENWDTB): Watchdog timer enable bit.
0: Enable
1: Disable
• Bit 6: Not used.
Reserved.
• Bit 5 (HLF): XTAL frequency selection
This bit will affect system oscillation only when Bit4 (OSC) is “1”. When OSC is”0”, HLF must be “0”.
<Note>: The transient point of system frequency between HXT and LXY is around 400 KHz.
• Bit 4 (OSC):Oscillator type selection.
0:RC type
1:XTAL type (XTAL1 and XTAL2)
• Bit 3 (HLP): Power selection.
0: Low power
1: High power
• Bit 2~0 (PR2~PR0): Protect Bit
PR2~PR0 are protect bits, protect type as following
The bit set to “1” all the time.
0: XTAL2 type (low frequency, 32.768KHz)
1: XTAL1 type (high frequency)
PR2
Bit12
0
0
0
-
Bit12~Bit0
Word 0
PR1
Bit11
0
0
1
-
Bit10
PR0
0
1
0
-
Bit9
Protect
Enable
Enable
Enable
-
Bit12~Bit0
Word 1
CLKS
Bit8
30
ENWDTB
WORD 0
Bit7
Bit6
-
HLF OSC HLP
Bit5
Bit4
Bit3
PR2
Bit2
EM78P156N
OTP ROM
07.29.2004 (V1.2)
PR1
Bit1
PR0
Bit0