hd64338342hw Renesas Electronics Corporation., hd64338342hw Datasheet - Page 160

• Manufacturer Part Number: hd64338342hw
• Description: Renesas 8-bit Single-chip Microcomputer H8 Family/h8/300l Super Low Power Series
• Manufacturer: Renesas Electronics Corporation.

Section 4 Clock Pulse Generators
Connect pin X
EXCL in register PMR2 to 1 to supply the external clock to the internal components of the device.
A connection example is shown in figure 4.9 (b).
Frequency
Duty
4. Notes on H8/38347 and H8/38447
In the H8/38347 and H8/38447 the subclock oscillator input pin is controlled by the EXCL bit in
the PMR2 register. When EXCL is cleared to 0 the X1 pin (resonator connection only) is used,
and when EXCL is set to 1 the EXCL pin (external clock only) is used. Caution is necessary when
switching from the H8/3847R to a program. Writing 1 to bit 7 in PMR2 (empty bit with initial
value 1 on H8/3847R) selects EXCL as the input pin, so no subclock is supplied internally even if
a resonator is connected. Furthermore, P31 becomes unusable. To prevent this it is necessary to
change the program so that 0 is written to the EXCL bit.
Rev. 6.00 Aug 04, 2006 page 124 of 680
REJ09B0145-0600
H8/38347 Group and H8/38447 Group
P3
1
to GND and leave pin X
Figure 4.9 (b) Pin Connection when Inputting External Clock
1
/UD/EXCL
X
X
1
2
(H8/38347 Group and H8/38447 Group)
2
open. Input an external clock to pin EXCL. Set bit
GND
Open
Subclock ( w)
45% to 55%
External clock input