HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 536

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

12.4
12.4.1
The FRC increments on clock input (internal or external).
Internal Clock Operation: Set the CKS1 and CKS0 bits in TCR to select which of the three
internal clocks created by dividing system clock ( /8, /32, /128) is used. Figure 12.4 shows
the timing.
External Clock Operation: Set the CKS1 and CKS0 bits in TCR to select the external clock.
External clock pulses are counted on the rising edge. The pulse width of the external clock must be
at least 6 system clocks ( ). A smaller pulse width will result in inaccurate operation. Figures 12.5
shows the timing.
External clock
Internal clock
FRC input
FRC input
input pin
Operation
FRC Count Timing
clock
clock
FRC
FRC
P
P
Figure 12.5 Count Timing (External Clock Operation)
Figure 12.4 Count Timing (Internal Clock Operation)
N – 1
N
N
N + 1
N + 1
521