14 8-BIT TIMERS (T8)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
14-9
D[11:8] Reserved (Ch.4 to Ch.7)
D[7:5]
Reserved
D4
TRMD: Count Mode Select Bit
Selects the T8 count mode.
1 (R/W): One-shot mode
0 (R/W): Repeat mode (default)
Setting TRMD to 0 sets T8 to repeat mode. In this mode, once the count starts, the timer continues to
run until stopped by the application program. When the counter underflows, the timer presets the coun-
ter to the reload data register value and continues the count. Thus, the timer periodically outputs an un-
derflow pulse. Set T8 to this mode to generate periodic interrupts or A/D triggers at desired intervals or
to generate a serial transfer clock.
Setting TRMD to 1 sets T8 to one-shot mode. In this mode, the timer stops automatically as soon as the
counter underflows. This means only one interrupt can be generated after the timer starts. Note that the
timer presets the counter to the reload data register value, then stops when an underflow occurs. Set T8
to this mode to set a specific wait time.
Note: Make sure the counter is halted before setting the count mode.
D[3:2]
Reserved
D1
PRESER: Timer Reset Bit
Resets the timer.
1 (W):
Reset
0 (W):
Ignored
0 (R):
Always 0 when read (default)
Writing 1 to this bit presets the counter to the reload data value.
D0
PRUN: Timer Run/Stop Control Bit
Controls the timer RUN/STOP.
1 (R/W): Run
0 (R/W): Stop (default)
The timer starts counting when PRUN is written as 1 and stops when written as 0. When the timer is
stopped, the counter data is retained until reset or until the next RUN state.
T8 Ch.
x
Interrupt Control Registers (T8_INT
x
)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
T8 Ch.
x
Interrupt
Control Register
(T8_INT
x
)
0x301108
|
0x301178
(16 bits)
D15–9 –
reserved
–
–
–
0 when being read.
D8
T8IE
T8 interrupt enable
1 Enable
0 Disable
0
R/W
D7–1 –
reserved
–
–
–
0 when being read.
D0
T8IF
T8 interrupt flag
1 Cause of
interrupt
occurred
0 Cause of
interrupt not
occurred
0
R/W Reset by writing 1.
D[15:9] Reserved
D8
T8IE: T8 Interrupt Enable Bit
Enables or disables interrupts caused by counter underflows for each channel.
1 (R/W): Interrupt enabled
0 (R/W): Interrupt disabled (default)
Setting T8IE to 1 enables T8 interrupt requests to the ITC; setting to 0 disables interrupts.
D[7:1]
Reserved