Z8F1680SH020SG Datasheet, PDF (345/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
320
24.3.2. Oscillator Control1 Register
The Oscillator Control 1 Register (OSCCTL1) enables/disables the secondary oscillator
circuits, which become the peripheral clock. The Oscillator Control1 Register is also used
to select the internal precision oscillator frequency.
The Oscillator Control 1 Register must be unlocked before writing. Unlock the Oscillator
Control 1 Register by writing the two-step sequence of E7H followed by 18H. This register
becomes locked upon successful completion of a register write to the OSCCTL1.
Table 171. Oscillator Control 1 Register (OSCCTL1)
Bits
7
6
5
4
3
Field
SECEN SECRDY
Reserved
Reset
0
0
1
0
0
R/W
R/W
R/W
R/W
R/W
R/W
Address
F87H
2
1
0
INTSEL
0
0
0
R/W
R/W
R/W
Bit
Description
[7]
Secondary Oscillator Enable
SECEN 1 = 32kHz Secondary Oscillator is enabled.
0 = 32 kHz Secondary Oscillator is disabled.
[6]
Secondary Oscillator Ready Flag
SECRDY 1 = 32kHz Secondary Oscillator is stable and running.
0 = 32 kHz Secondary Oscillator is not running.
[5:3]
Reserved; must be 0.
[2:0]
INTSEL
Internal Precision Oscillator Frequency Select
000 = Internal Precision Oscillator Frequency is 11.0592 MHz.
001 = Internal Precision Oscillator Frequency is 5.5296 MHz.
010 = Internal Precision Oscillator Frequency is 2.7648 MHz.
011 = Internal Precision Oscillator Frequency is 1.3824 MHz.
100 = Internal Precision Oscillator Frequency is 0.6912 MHz.
101 = Internal Precision Oscillator Frequency is 0.3456 MHz.
110 = Internal Precision Oscillator Frequency is 0.0864 MHz.
111 = Internal Precision Oscillator Frequency is 0.0432 MHz.
PS025015-1212
PRELIMINARY
Oscillator Control