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EM78P259N/260N
8-Bit Microprocessor with OTP ROM
Product Specification (V1.2) 05.18.2007
• 67
(This specification is subject to change without further notice)
6.13 Code Option
EM78P259N/260N has two Code option words and one Customer ID word that are not
part of the normal program memory.
Word 0 Word1 Word 2
Bit12 ~ Bit0 Bit12 ~ Bit0 Bit12 ~ Bit0
6.13.1 Code Option Register (Word 0)
Word 0
Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
– – – TYPE CLKS ENWDTB OSC2 OSC1 OSC0 HLP PR2 PR1 PR0
Bits 12 ~ 10: Not used (reserved). These bits are set to “1” all the time
Bit 9 (TYPE): Type selection for EM78P259N or EM78P260N
0 = EM78P260N
1 = EM78P259N (default)
Bit 8 (CLKS): Instruction period option bit
0 = two oscillator periods
1 = four oscillator periods (default)
Refer to Section 6.15 for Instruction Set
Bit 7 (ENWDTB): Watchdog timer enable bit
0 = Enable
1 = Disable (default)
Bits 6, 5 & 4 (OSC2, OSC1 & OSC0): Oscillator Mode Selection bits
Oscillator Modes OSC2 OSC1 OSC0
ERC
1
(External RC oscillator mode); P70/OSCO acts as P70 0 0 0
ERC
1
(External RC oscillator mode); P70/OSCO acts as OSCO 0 0 1
IRC
2
(Internal RC oscillator mode); P70/OSCO acts as P70 0 1 0
IRC
2
(Internal RC oscillator mode); P70/OSCO acts as OSCO 0 1 1
LXT
3
(Low Crystal oscillator mode) 1 1 0
HXT
3
High Crystal oscillator mode) (default) 1 1 1
1
In ERC mode, OSCI is used as oscillator pin. OSCO/P70 is defined by code option Word 0 Bit 6 ~ Bit 4.
2
In IRC mode, P55 is normal I/O pin. OSCO/P70 is defined by code option Word 0 Bit 6 ~ Bit 4.
3
In LXT and HXT modes; OSCI and OSCO are used as oscillator pins. These pins cannot and
should not be defined as normal I/O pins.
NOTE
The transient point of the system frequency between HXT and LXY is around 400kHz.