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CHAPTER 1 INTRODUCTION
20
Clock inputs. Connect an oscillator having a frequency of 32.768 kHz to the CLKX1 and CLKX2
pins, or connect an external clock to the CLKX1 pin.
"
RTC (internal)
Clock having a frequency of 32.768 kHz. This clock is generated from the clock input to the CLKX1
and CLKX2 pins. It is used in the PMU and the RTC units. In Hibernate mode, the internal clock of
the CPU core is stopped and the V
R
4101 operates based on the RTC.
"
PClock (internal)
Clock for the CPU core operation. This clock is generated from the clock input to the CLKX1 and
CLKX2 pins multiplied at the PLL. It has a frequency of 33 MHz.
"
MasterOut (internal)
Clock for the CPU core bus operation, and used for interrupt control. This clock has a frequency of
1/4 of the PClock frequency.
"
TClock (internal)
Clock for the CPU core bus operation, the V
R
4101 internal bus operation, and operation of the
peripheral units. This clock has a frequency of 1/2 of the PClock frequency.
"
PCMCLK (output)
Clock supplied to the PCMCIA controller. This clock has a frequency of 8.25 MHz.
"
ADCLK (output)
Clock supplied to the A/D converter. The frequency of this clock is set on the PIUSTBLREG
register.
Figure 1-9 shows an external circuit of the clock oscillator.
Figure 1-9. External Circuit of Clock Oscillator
(a) Crystal oscillation
(b) External clock
V
R
4101
GND
CLKX1
CLKX2
V
R
4101
CLKX1
CLKX2
External
clock
Open
Cautions 1. When using a clock oscillator, run wires in the area of this figure shown by broken
lines, according to the following rules, to avoid effects such as stray capacitance:
Minimize the wire.
Never cause the wires to cross other signal lines or run near a line carrying a
large varying current.