MC68HC05L16 Datasheet, PDF (68/146 Pages) Freescale Semiconductor, Inc – Microcontrollers

Oscillators/Clock Distributions
Table 7-6. System Bus Clock Frequency Selection
SYS1 SYS0
0
0
0
1
1
0
1
1
Divide Ratio
OSC ÷ 2
OSC ÷ 4
OSC ÷ 64
XOSC ÷ 2
CPU Bus Frequency (Hz)
OSC = 4.0 M OSC = 4.1943 M XOSC = 32.768 k
2.0 M
2.0972 M
—
1.0 M
1.0486 M
—
62.5 k
65.536 k
—
—
—
16.384 k
FOSCE — Fast (Main) Oscillator Enable
The FOSCE bit controls the main oscillator activity. This bit should not be cleared by the CPU when
the main oscillator is selected as the system clock source.
When this bit is cleared:
1. OSC is shut down.
2. 7-bit divider at the OSC input and POR counter are initialized to $0078.
3. FTUP flag is cleared.
When this bit is set:
1. Main oscillator starts again.
2. FTUP flag is set by the POR counter overflow (8072 clocks).
OPTM — Option Map Select
The OPTM bit selects one of two register maps at $0000–$000F. This bit is cleared on reset.
0 = Main register map selected
1 = Option map selected
MC68HC05L16 • MC68HC705L16 Data Sheet, Rev. 4.1
68
Freescale Semiconductor