BAT32G1x9 user manual | Chapter 4 Clock generation circuit
96 / 1149
Rev.1.02
4.4 System clock oscillation circuit
4.4.1
X1 oscillation circuit
The X1 oscillation circuit oscillates by connecting a crystal resonator or ceramic resonator (1 to 20 MHz)
connected to pins X1 and X2. An external clock can also be input, in which case a clock signal must be input
to the EXCLK pin.
When using X1 oscillation circuitry, the bit7 and bit6 (EXCLK, OSCSEL) inputs of registers (CMC) must be
controlled for the clock operating mode Line the following settings:
•
Crystal or ceramic oscillation: EXCLK, OSCSEL=0, 1
•
External clock inputs:
EXCLK, OSCSEL=1, 1
When the X1 oscillation circuit is not used, it must be set to input port mode (EXCLK, OSCSEL=0, 0).
Also, when it is not used as an input port, refer to "Handling of Unused Pins in Table 2-4
".
An example of an external circuit for the X1 oscillation circuit is shown in Figure Fig. 4-18.
Fig. 4-1818
X1 oscillation circuit
Vss
X1
X2
Crystal oscilator or
ceramic oscillator
(a) Crystal or Ceramic oscilator
(b) external clock
EXCLK
external clock
Precautions are shown on the following page.
4.4.2
XT1 oscillation circuit
The XT1 oscillation circuit passes through a crystal resonator (32.768kHz (TYP.)) connecting the XT1 pin
to the XT2 pin) to oscillate. When using the XT1 oscillation circuit, the bit4 (OSCSELS) of the clock operating
mode control register (CMC) must be set to "1" to be used to input an external clock, which must be given
The EXCLKS pin input clock signal.
When using XT1 oscillation circuitry, the clock operating mode must control bit5 and bit4 (EXCLKS,
OSCSELS) of registers (CMC (make the following settings:
•
Crystal oscillation: EXCLKS,
OSCSELS = 0,
1
•
External clock inputs:
EXCLKS,
OSCSELS=1,
1
When the XT1 oscillation circuit is not used, it must be set to input port mode (EXCLKS, OSCSELS=0, 0).
Also, when it is not used as an input port, refer to "Handling of Unused Pins in Table 2-4
". An example
of an external circuit for the XT1 oscillation circuit is shown in Figure Fig. 4-19.