XC68HC705JJ7 Motorola, XC68HC705JJ7 Datasheet - Page 76

• Manufacturer Part Number: XC68HC705JJ7
• Description: MICROCONTROLLER
• Manufacturer: Motorola

Operating Modes
6.3 Oscillator Source
Advance Information
76
Address:
The microcontroller unit (MCU) can be clocked by either an internal
low-power oscillator (LPO) without external components or by an
external pin oscillator (EPO) which uses external components. The
enable and selection of the clock source is determined by the state of the
oscillator select bits (OM1 and OM2) in the interrupt status and control
register (ISCR) as shown in
IRQE — External Interrupt Request Enable Bit
OM1 and OM2 — Oscillator Select Bits
Reset:
Read:
Write:
This read/write bit enables external interrupts. Refer to
Interrupts
These bits control the selection and enabling of the oscillator source
for the MCU. One choice is the internal LPO and the other oscillator
is the EPO which is common to most M68HC05 MCU devices. The
EPO uses external components like filter capacitors and a crystal or
ceramic resonator and consumes more power than the LPO. The
selection and enable conditions for these two oscillators are shown in
Table
and disables the EPO.
Therefore, the lowest power is consumed when OM1 is cleared. The
state with both OM1 and OM2 set is provided so that the EPO can be
started up and allowed to stabilize while the LPO still clocks the MCU.
$000D
Figure 6-1. IRQ Status and Control Register (ISCR)
IRQE
Bit 7
6-1. Reset clears OM1 and sets OM2, which selects the LPO
1
for more details.
= Unimplemented
Operating Modes
OM2
6
1
OM1
5
0
Figure
MC68HC705JJ7 • MC68HC705JP7 — REV 4
R
4
0
0
6-1.
IRQF
R
3
0
= Reserved
2
0
0
IRQR
Section 4.
1
0
0
MOTOROLA
Bit 0
0
0