em78p257 ELAN Microelectronics Corp, em78p257 Datasheet - Page 65

• Manufacturer Part Number: em78p257
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

4.13 CODE OPTION
This specification is subject to change without prior notice.
/RESETEN
I R O U T
1. Code Option Register (Word 0)
I R O U T
Fosco
Fosc
I R O U T
Fosco
Bit12
Fosc
Fig. 29 CASE 1 shows a typical long pulse(DP=00;MF=10;HF=1;LGP=1;PWM=0); CASE 2 shows
the same long pulse after being modulated with a frequency of 1/4Fosc
(DP=00;MF=10;HF=1;LGP=1;PWM=0).
EM78P257A/B has one CODE option word and one Customer ID word, which are not a part of the normal
program memory.
• Bit 12 (/RESETEN): Define Pin4(EM78P257A) or Pin5(EM78P257B) as a reset pin
• Bit 11 (/ENWDT): Watchdog timer enable bit.
Fig. 30 Continuous pulse train (DP=00;MF=10;HF=0;LGP=0;PWM==1).
0: /RESET enable
1: /RESET disable
C A S E 1
C A S E 2
/ENWDT
Bit11
start
s t a r t
L o w -t i m e R e g i s t e r = 3
Code option12~0
L o w-t i m e R e g i s t e r = 3
CLKS
Bit10
Bit12~Bit0
Word 0
OSC2
Bit9
OSC1
Bit8
H i g h -t i m e R e g i s t e r = 2
N u m b e r o f p u l s e s = 3
OSC0
Bit7
65
Customer’s ID
/PTB
Bit6
Bit12~Bit0
Word 1
SUT
Bit5
TYP
Bit4
RCOUT
Bit3
I n t e r r u p t t o C P U
RCM1
Bit2
EM78P257
07.27.2004 (V1.4)
OTP ROM
S o f t w a r e t i m e
RCM0
Bit1
s t a r t
Bit0
-