EM78468
8-BIT Microcontroller
4.11 Code Options
The EM78468 has one Code Option word that is not a part of the normal program
memory.
Code Option Register (Word 0)
Word 0
Bit6 Bit5
CYES HLFS ENWDTB FSMD FMMD1 FMMD0 HLP
Bit12~10 Bit9 Bit8
Bit7
Bit4
Bit3 Bit2 Bit1 Bit0
1
0
0
0
• Bit 12 ~ 10: Not used.
These bits are set to “1” all the time.
• Bit 9 (CYES): Cycle select for JMP and CALL instructions
CYES = “0”: only one instruction cycle (JMP or CALL) can be executed
CYES = “1”: two instructions cycles (JMP and CALL) can be executed
• Bit 8 (HLFS): main or sub-oscillator select
HLFS = “0”: CPU is set to select sub-oscillator when reset occurs.
HLFS = “1”: CPU is set to select main-oscillator when reset occurs.
• Bit 7(ENWDTB): Watchdog timer enable/disable bit.
ENWDTB = “0”: Enable watchdog timer.
ENWDTB = “1”: Disable watchdog timer.
• Bit 6 (FSMD): sub-oscillator type selection.
• Bit 5, 4 (FMMD1, 0): main Oscillator type selection.
FSMD
FMMD1 FMMD0
Main Oscillator Type
Sub Oscillator Type
RC type
0
0
0
1
1
1
0
0
1
0
0
1
0
1
X
0
1
X
RC type
XTAL type
PLL type
RC type
XTAL type
PLL type
RC type
RC type
XTAL type
XTAL type
XTAL type
• Bit 3 (HLP): Power consumption selection. If your system usually runs in green mode, it
must be set to low power consumption to help support the energy saving issue. We
recommend that low power consumption mode is slected.
HLP = “0”: Low power consumption mode
HLP = “1”: High power consumption mode
• Bit 2~0 :
These bits are set to “0” all the time.
52 •
Product Specification (V1.1) 04.11.2005
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
