618
Table A.51 TCSR Bit Functions
Bit
Bit Name
Value
Description
7
Overflow flag (OVF)
0
No TCNT overflow in interval timer mode
(Initial value)
Clear Condition: OVF read, then 0 written in OVF
1
TCNT overflow generated in interval timer mode
6
Timer mode select (WT/
IT
)
0
Interval timer mode: When TCNT overflows, interval
timer interrupt (ITI) request sent to CPU (Initial value)
1
Watchdog timer mode: When TCNT overflows,
WDTOVF
signal is output externally
*
5
Timer enable (TME)
0
Timer disable: TCNT initialized at H'00 and count-
up halted
(Initial value)
1
Timer enable: TCNT starts counting up. When
TCNT overflows, a
WDTOVF
signal or interrupt is
generated
2–0
Clock select 2–0
Clock
Overflow cycle (
φ
=20 MHz)
(CKS2–CKS0)
0 0 0
φ
/2 (Initial value)
25.6 µs
0 0 1
φ
/64
819.2 µs
0 1 0
φ
/128
1.6 ms
0 1 1
φ
/256
3.3 ms
0 0 0
φ
/512
6.6 ms
0 0 1
φ
/1024
13.1 ms
0 1 0
φ
/4096
52.4 ms
0 1 1
φ
/8192
104.9 ms
Note:
*
When the RSTE bit in RSTCSR is 1, an internal reset signal is also generated
simultaneously with the
WDTOVF
signal when TCNT overflows in watchdog timer mode.
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Страница 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
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