NEC uPD78056Y - Manual (Page 245)

245
CHAPTER 10 WATCH TIMER
(2) Watch timer mode control register (TMC2)
This register sets the watch timer operating mode, watch flag set time and prescaler interval time and enables/
disables prescaler and 5-bit counter operations. TMC2 is set with a 1-bit or 8-bit memory manipulation
instruction.
RESET input sets TMC2 to 00H.
Figure 10-3. Watch Timer Mode Control Register Format
Caution When the watch timer is used, the prescaler should not be cleared frequently.
Remarks 1. f
W
: Watch timer clock frequency (f
XX
/2 7 or f
XT
)
2. f
XX
: Main system clock frequency (f
X
or f
X
/2)
3. f X : Main system clock oscillation frequency
4. f XT : Subsystem clock oscillation frequency
0
7
TMC26
6
TMC25 TMC24
4
TMC23
3 2 1 0
FF4AH
Address
TMC2
Symbol
TMC22 TMC21 TMC20
5
00H
After
Reset
R/W
R/W
0
1
TMC23
f XX = 5.0 MHz Operation
2 14 /f W (0.4 sec)
2 13 /f W (0.2 sec)
Watch Flag Set Time Selection
0
0
0
0
1
1
Other than above
0
0
1
1
0
0
0
1
0
1
0
1
TMC26 TMC25 TMC24
f XX = 5.0 MHz Operation
2 4 /f W (410 s)
2 5 /f
W
(819 s)
2 6 /f
W
(1.64 ms)
2 7 /f
W
(3.28 ms)
2 8 /f W (6.55 ms)
2 9 /f W (13.1 ms)
Setting prohibited
f XX = 4.19 MHz Operation
2 4 /f W (488 s)
2 5 /f
W
(977 s)
2 6 /f
W
(1.95 ms)
2 7 /f
W
(3.91 ms)
2 8 /f W (7.81 ms)
2 9 /f W (15.6 ms)
f XT = 32.768 kHz Operation
2 4 /f W (488 s)
2 5 /f
W
(977 s)
2 6 /f
W
(1.95 ms)
2 7 /f
W
(3.91 ms)
2 8 /f W (7.81 ms)
2 9 /f W (15.6 ms)
Prescaler Interval Time Selection
µ
µ
µ
µ
µ
µ
f XX = 4.19 MHz Operation
2 14 /f W (0.5 sec)
2 13 /f W (0.25 sec)
f XT = 32.768 kHz Operation
2 14 /f W (0.5 sec)
2 13 /f W (0.25 sec)
TMC22
0
1
5-Bit Counter Operation Control
Clear after operation stop
Operation enable
TMC21
0
1
Prescaler Operation Control
Clear after operation stop
Operation enable
TMC20
0
1
Watch Operating Mode Selection
Normal operating mode (flag set at f W /2 14 )
Fast feed operating mode (flag set at f W /2 5 )