HD64F38602R Datasheet, PDF (213/552 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

Section 10 Timer W
10.6 Timer W Operating Modes
Table 10.3 shows the timer W operating modes.
Table 10.3 Timer W Operating Modes
Active
Sleep
Oscillation Stabilization Time
Clock High- Medium- High- Medium-
Sub- Sub-
Standby to Subsleep to Watch to
Source speed speed
speed speed Watch active sleep Standby Active
Active
Active
FTCI
ο
ο
ο
ο
×
ο
ο
×
×
×
×
φw, φw/4, ο
ο
ο
ο
×
ο
ο
×
×
×
×
φw/16
φ, φ/2, φ/4, ο
ο
ο
ο
×
×
×
×
×
×
×
φ/8
[Legend] ο: Counting enabled
×: Counting disabled (Counter value retained)
10.7 Usage Notes
The following types of contention or operation can occur in timer W operation.
1. The pulse width of the input clock signal and the input capture signal must be at least two
system clock cycles; shorter pulses will not be detected correctly. The system clock described
here indicates the clock set for the CPU operation. For example, in the φw/8 operation, at least
φw x 16 clock cycles are required as the pulse width.
2. Writing to registers is performed in the T2 state of a TCNT write cycle.
If counter clear signal occurs in the T2 state of a TCNT write cycle, clearing of the counter
takes priority and the write is not performed, as shown in figure 10.24. If counting-up is
generated in the TCNT write cycle to contend with the TCNT counting-up, writing takes
precedence.
3. Depending on the timing, TCNT may be incremented by a switch between different internal
clock sources. When TCNT is internally clocked, an increment pulse is generated from the
rising edge of an internal clock signal, that is, the divided system clock (φ). Therefore, as
shown in figure 10.25 the switch is from a low clock signal to a high clock signal, the
switchover is seen as a rising edge, causing TCNT to increment.
4. If timer W enters module standby mode while an interrupt request is generated, the interrupt
request cannot be cleared. Before entering module standby mode, disable interrupt requests.
Rev. 3.00 May 15, 2007 Page 181 of 518
REJ09B0152-0300