External Clock Input Circuit; Prescaler - NEC 78K0S/KA1+ User Manual

Figure 5-7. Examples of Incorrect Resonator Connection (2/2)
(e) Signals are fetched
V
SS
5.4.3

External clock input circuit

This circuit supplies a clock from an external IC to the X1 pin.
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.
For details of the option byte, refer to CHAPTER 17 OPTION BYTE. For details of I/O ports, refer to CHAPTER 4
PORT FUNCTIONS.
5.4.4

Prescaler

The prescaler divides the clock (f
the peripheral hardware. It also divides the clock to peripheral hardware (f
CPU.
Remark The clock output by the oscillator selected by the option byte (high-speed internal oscillator,
crystal/ceramic oscillator, or external clock input circuit) is divided. For details of the option byte, refer to
CHAPTER 17 OPTION BYTE.
74
CHAPTER 5 CLOCK GENERATORS
X1 X2
) output by the system clock oscillator to generate a clock (f
X
User's Manual U16898EJ3V0UD
) to be supplied to
XP
) to generate a clock to be supplied to the
XP