HD6413308 Hitachi Semiconductor, HD6413308 Datasheet - Page 174

• Manufacturer Part Number: HD6413308
• Description: Hitachi Single-Chip MicroComputer
• Manufacturer: Hitachi Semiconductor

Bit 1
OS1
0
0
1
1
7.3 Operation
7.3.1 TCNT Incrementation Timing
The timer counter increments on a pulse generated once for each period of the clock source selected
by bits CKS2 to CKS0 of the TCR.
Internal Clock: Internal clock sources are created from the system clock by a prescaler. The
counter increments on an internal TCNT clock pulse generated from the falling edge of the
prescaler output, as shown in figure 7-2. Bits CKS2 to CKS0 of the TCR can select one of the
three internal clocks (Ø/8, Ø/64, or Ø/1024).
External Clock: If external clock input (TMCI) is selected, the timer counter can increment on the
rising edge, the falling edge, or both edges of the external clock signal. Figure 7-3 shows
incrementation on both edges of the external clock signal.
The external clock pulse width must be at least 1.5 system clock periods for incrementation on a
single edge, and at least 2.5 system clock periods for incrementation on both edges. See figure 7.4.
The counter will not increment correctly if the pulse width is shorter than these values.
Ø
Prescaler
output
TCNT clock
pulse
TCNT
Bit 0
OS0
0
1
0
1
N–1
Figure 7-2. Count Timing for Internal Clock Input
Description
No change when compare-match A occurs.
Output changes to “0” when compare-match A occurs.
Output changes to “1” when compare-match A occurs.
Output inverts (toggles) when compare-match A occurs.
N
160
(Initial value)
N+1