S1C63666 TECHNICAL MANUAL
EPSON
71
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Stopwatch Timer)
Key mask
In stopwatch applications, some functions may be controlled by a combination of keys including
direct RUN or direct LAP. For instance, the RUN key can be used for other functions, such as reset and
setting a watch, by pressing the RUN key with another key. In this case, the direct RUN function or
direct LAP function must be invalid so that it does not function. For this purpose, the key mask
function is set so that it judges concurrence of input keys and invalidates RUN and LAP functions. A
combination of the key inputs for this judgment can be selected using the DKM0–DKM2 registers.
Table 4.10.5.2 Key mask selection
DKM2
0
0
0
0
1
1
1
1
DKM1
0
0
1
1
0
0
1
1
DKM0
0
1
0
1
0
1
0
1
Mask key combination
None (at initial reset)
K02
K02, K03
K02, K03, K10
K10
K10, K11
K10, K11, K12
K10, K11, K12, K13
RUN or LAP inputs become invalid in the following status.
1. The RUN or LAP key is pressed when one or more keys that are included in the selected combina-
tion (here in after referred to as mask) are held down.
2. The RUN or LAP key has been pressed when the mask is released.
f
OSC1
/32 (1,024 Hz)
Direct RUN/LAP input
Key mask
valid
invalid
invalid
invalid
Fig. 4.10.5.4 Operation of key mask
RUN or LAP inputs become valid in the following status.
1. Either the RUN or LAP key is pressed independently if no other key is been held down.
2. Both the RUN and LAP keys are pressed at the same time if no other key is held down. (RUN and
LAP functions are effective.)
3. The RUN or LAP key is pressed if either is held down. (RUN and LAP functions are effective.)
4. Either the RUN or LAP key and the mask key are pressed at the same time if no other key is held
down.
5. Both the RUN and LAP keys and the mask key are pressed at the same time if no other key is held
down. (RUN and LAP functions are effective.)
*
Simultaneous key input is referred to as two or more key inputs are sampled at the same falling
edge of 1,024 Hz clock.
