Datasheet

CHAPTER 5 CLOCK GENERATORS
User’s Manual U18172EJ3V0UD
81
Figure 5-7. Examples of Incorrect Resonator Connection (2/2)
(e) Signals are fetched
V SS
X1 X2
5.4.3 External clock input circuit
This circuit supplies a clock from an external IC to the X1 pin
Note 1
.
If external clock input is selected by the option byte as the system clock source, the X2 pin can be used as an I/O
port pin.
Note 2
For details of the option byte, refer to CHAPTER 15 OPTION BYTE. For details of I/O ports, refer to CHAPTER 4
PORT FUNCTIONS.
Notes 1.
μ PD78F920x: X1 pin, μ PD78F950x: EXCLK pin
2. μ PD78F920x only
5.4.4 Prescaler
The prescaler divides the clock (f
X) output by the system clock oscillator to generate a clock (fXP) to be supplied to
the peripheral hardware. It also divides the clock to peripheral hardware (f
XP) to generate a clock to be supplied to the
CPU.
Remark The clock output by the oscillator selected by the option byte (high-speed internal oscillator,
crystal/ceramic oscillator
Note
, or external clock input circuit) is divided. For details of the option byte, refer
to CHAPTER 15 OPTION BYTE.
Note
μ PD78F920x only
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