CHAPTER 7 8-BIT TIMER/EVENT COUNTERS 50 AND 51
Preliminary User’s Manual U19014EJ1V0UD
188
7.4.2 Operation as external event counter
The external event counter counts the number of external clock pulses to be input to the TI5n pin by 8-bit timer
counter 5n (TM5n).
TM5n is incremented each time the valid edge specified by timer clock selection register 5n (TCL5n) is input.
Either the rising or falling edge can be selected.
When the TM5n count value matches the value of 8-bit timer compare register 5n (CR5n), TM5n is cleared to 0
and an interrupt request signal (INTTM5n) is generated.
Whenever the TM5n value matches the value of CR5n, INTTM5n is generated.
Setting
<1> Set each register.
•
Set the port mode register (PM17 or PM33)
Note
to 1.
•
TCL5n: Select TI5n pin input edge.
TI5n pin falling edge
→
TCL5n = 00H
TI5n pin rising edge
→
TCL5n = 01H
•
CR5n: Compare
value
•
TMC5n: Stop the count operation, select the mode in which clear & start occurs on match of TM5n and
CR5n, disable the timer F/F inversion operation, disable timer output.
(TMC5n = 0000
××
00B
×
= Don’t care)
<2> When TCE5n = 1 is set, the number of pulses input from the TI5n pin is counted.
<3> When the values of TM5n and CR5n match, INTTM5n is generated (TM5n is cleared to 00H).
<4> After these settings, INTTM5n is generated each time the values of TM5n and CR5n match.
Note
8-bit timer/event counter 50: PM17
8-bit timer/event counter 51: PM33
Remark
For how to enable the INTTM5n signal interrupt, see
CHAPTER 13 INTERRUPT FUNCTIONS
.
Figure 7-12. External Event Counter Operation Timing (with Rising Edge Specified)
TI5n
TM5n count value
CR5n
INTTM5n
00H
01H
02H
03H
04H
05H
N
−
1
N
00H
01H
02H
03H
N
Count start
Remark
N = 00H to FFH
n = 0, 1
electronic components distributor