Epson S1C63558 - Manual (Page 73)

S1C63558 TECHNICAL MANUAL EPSON 63
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)
4.9.4 I/O memory of stopwatch timer
Table 4.9.4.1 shows the I/O addresses and the control bits for the stopwatch timer.
Table 4.9.4.1 Control bits of stopwatch timer
Address Comment
D3 D2
Register
D1 D0 Name Init
∗
1 1 0
W R/W R
FF7CH
0 0 SWRST SWRUN
0 ∗ 3
0
∗ 3
SWRST ∗ 3
SWRUN
– ∗ 2
–
∗ 2
Reset
0
Reset
Run
Invalid
Stop
Unused
Unused
Stopwatch timer reset (writing)
Stopwatch timer Run/Stop
R
FF7DH
SWD3 SWD2 SWD1 SWD0
SWD3
SWD2
SWD1
SWD0
0
0
0
0
Stopwatch timer data
BCD (1/100 sec)
SWD7
SWD6
SWD5
SWD4
0
0
0
0
Stopwatch timer data
BCD (1/10 sec)
R
FF7EH
SWD7 SWD6 SWD5 SWD4
FFE7H
0 0 EISW1 EISW10
R R/W
0
∗
3
0
∗ 3
EISW1
EISW10
–
∗
2
–
∗ 2
0
0
Enable
Enable
Mask
Mask
Unused
Unused
Interrupt mask register (Stopwatch timer 1 Hz)
Interrupt mask register (Stopwatch timer 10 Hz)
FFF7H
0 0 ISW1 ISW10
R R/W
0
∗
3
0
∗ 3
ISW1
ISW10
–
∗
2
–
∗ 2
0
0
(R)
Yes
(W)
Reset
(R)
No
(W)
Invalid
Unused
Unused
Interrupt factor flag (Stopwatch timer 1 Hz)
Interrupt factor flag (Stopwatch timer 10 Hz)
*1 Initial value at initial reset
*2 Not set in the circuit
*3 Constantly "0" when being read
SWD0–SWD7: Stopwatch timer data (FF7DH, FF7EH)
The 1/100 sec and the 1/10 sec data (BCD) can be read from SWD0–SWD3 and SWD4–SWD7, respec-
tively. These eight bits are read only, and writing operations are invalid.
At initial reset, the timer data is initialized to "00H".
SWRST: Stopwatch timer reset (FF7CH•D1)
When "1" is written: Stopwatch timer reset
When "0" is written: No operation
Reading: Always "0"
The stopwatch timer is reset by writing "1" to SWRST. All timer data is set to "0". When the stopwatch
timer is reset in the RUN status, operation restarts immediately. Also, in the STOP status the reset data is
maintained. No operation results when "0" is written to SWRST.
This bit is write-only, and so is always "0" at reading.
SWRUN: Stopwatch timer RUN/STOP control register (FF7CH•D0)
Controls RUN/STOP of the stopwatch timer.
When "1" is written: RUN
When "0" is written: STOP
Reading: Valid
The stopwatch timer enters the RUN status when "1" is written to the SWRUN register, and the STOP
status when "0" is written.
In the STOP status, the timer data is maintained until the next RUN status or the timer is reset. Also,
when the STOP status changes to the RUN status, the data that is maintained can be used for resuming
the count.