3.
Pin configuration
Table 9-19 shows the asynchronous event counter pin configuration.
Table 9-19
Pin Configuration
Name
Abbrev.
I/O
Function
Asynchronous event input H
AEVH
Input
Event input pin for input to event counter H
Asynchronous event input L
AEVL
Input
Event input pin for input to event counter L
4.
Register configuration
Table 9-20 shows the register configuration of the asynchronous event counter.
Table 9-20
Asynchronous Event Counter Registers
Name
Abbrev.
R/W
Initial Value
Address
Event counter control/status register
ECCSR
R/W
H'00
H'FF95
Event counter H
ECH
R
H'00
H'FF96
Event counter L
ECL
R
H'00
H'FF97
Clock stop register 2
CKSTP2
R/W
H'FF
H'FFFB
9.7.2
Register Descriptions
1.
Event counter control/status register (ECCSR)
ECCSR is an 8-bit read/write register that controls counter overflow detection, counter resetting,
and halting of the count-up function.
ECCSR is initialized to H'00 upon reset.
Bit 7: Counter overflow flag H (OVH)
Bit 7 is a status flag indicating that ECH has overflowed from H'FF to H'00. This flag is set when
ECH overflows. It is cleared by software but cannot be set by software. OVH is cleared by reading
it when set to 1, then writing 0.
OVH
CUEL
CRCH
CRCL
OVL
—
CH2
CUEH
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
R/W
*
R/W
R/W
R/W
R/W
*
R/W
R/W
R/W
Bit
Note:
*
Bits 7 and 6 can only be written with 0, for flag clearing.
Initial Value
Read/Write
241