Z8F1680SH020SG Datasheet, PDF (305/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
280
Table 141. Flash Option Bits at Program Memory Address 0001H
Bits
7
6
5
4
3
2
Field
EXTLTMG
FLASH_WR_
PRO_EN
EXTL_AO
Reserved
Reset
U
U
U
U
U
U
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Address
Program Memory 0001H
Note: U = Unchanged by Reset. R/W = Read/Write.
1
0
X2_Mode ^X2TL_AO
U
U
R/W
R/W
Bit
[7:6]
EXTLTMG
[5]
FLASH_WR_
PRO_EN
[4]
EXTL_AO
[3:2]
[1]
X2_Mode
[0]
X2TL_AO
Description
External Crystal Reset Timing
00 = 500 Internal Precision Oscillator Cycles.
01 = 1000 Internal Precision Oscillator Cycles.
10 = 5000 Internal Precision Oscillator Cycles.
11 = 10,000 Internal Precision Oscillator Cycles.
Flash Write Operation Protect
0 = Flash write protect disable.
1 = Flash write protect with internal LVD.
External Crystal Always ON
0 = Crystal oscillator is enabled during Reset, resulting in longer reset timing.
1 = Crystal oscillator is disabled during Reset, resulting in shorter reset timing.
Note: This bit determines the state of the external crystal oscillator at Reset. Its selection as system
clock must be performed in the Oscillator Control Register (OSCCTL0).
Reserved; must be 00.
Secondary Crystal Mode Select
0 = External clock input.
1 = External 32 kHz watch crystal.
Secondary Crystal Always ON
0 = Secondary Crystal Oscillator is enabled during reset.
1 = Secondary Crystal Oscillator is disabled during reset.
Note:
This bit determines state of the Secondary Crystal Oscillator at Reset. Its selection as
peripheral clock must be performed in the Peripheral Control (for example, Timer
Control2) register.
PS025015-1212
PRELIMINARY
Flash Option Bits