CHAPTER 7 8-BIT TIMER/EVENT COUNTER
146
(3) Square-wave output operation
Square wave signals can be generated at the user-specified frequency. The frequency, or pulse interval is
determined by the value preset in the 8-bit compare registers (CR10 and CR20). To set a count value, set
the value of the high-order 8 bits to CR20, and the value of the low-order 8 bits to CR10.
The TO2/P32 pin output status is reversed at intervals of the count value preset to CR10 and CR20 by setting
bit 4 (TOE2) of the 8-bit timer output control register (TOC1) to 1. This enables a square wave with any selected
frequency to be output.
Table 7-10. Square-Wave Output Ranges when 2-Channel 8-Bit Timer/Event Counters
(TM1 and TM2) are Used as 16-Bit Timer/Event Counter
TCL13
TCL12
TCL11
TCL10
Minimum Pulse Time
Maximum Pulse Time
Resolution
0
1
0
1
2
×
1/f
X
(400 ns)
2
9
×
1/f
X
(26.2 ms)
2
×
1/f
X
(400 ns)
0
1
1
0
2
2
×
1/f
X
(800 ns)
2
10
×
1/f
X
(52.4 ms)
2
2
×
1/f
X
(800 ns)
0
1
1
1
2
3
×
1/f
X
(1.6
μ
s)
2
11
×
1/f
X
(104.9 ms)
2
3
×
1/f
X
(1.6
μ
s)
1
0
0
0
2
4
×
1/f
X
(3.2
μ
s)
2
12
×
1/f
X
(209.7 ms)
2
4
×
1/f
X
(3.2
μ
s)
1
0
0
1
2
5
×
1/f
X
(6.4
μ
s)
2
13
×
1/f
X
(419.4 ms)
2
5
×
1/f
X
(6.4
μ
s)
1
0
1
0
2
6
×
1/f
X
(12.8
μ
s)
2
14
×
1/f
X
(838.9 ms)
2
6
×
1/f
X
(12.8
μ
s)
1
0
1
1
2
7
×
1/f
X
(25.6
μ
s)
2
15
×
1/f
X
(1.7 s)
2
7
×
1/f
X
(25.6
μ
s)
1
1
0
0
2
8
×
1/f
X
(51.2
μ
s)
2
16
×
1/f
X
(3.4 s)
2
8
×
1/f
X
(51.2
μ
s)
1
1
0
1
2
9
×
1/f
X
(102.4
μ
s)
2
17
×
1/f
X
(6.7 s)
2
9
×
1/f
X
(102.4
μ
s)
1
1
1
0
2
10
×
1/f
X
(204.8
μ
s)
2
18
×
1/f
X
(13.4 s)
2
10
×
1/f
X
(204.8
μ
s)
1
1
1
1
2
12
×
1/f
X
(819.2
μ
s)
2
20
×
1/f
X
(53.7 s)
2
12
×
1/f
X
(819.2
μ
s)
Remarks 1.
f
X
: Main system clock frequency
2.
TCL10 to TCL13: Bits 0 to 3 of timer clock select register 1 (TCL1)
3.
Values in parentheses when operated at f
X
= 5.0 MHz.
Figure 7-13. Square-Wave Output Operation Timings
00H
Count clock
Count start
Level reverse
counter clear
Interval time
TM1
TM2
CR10
CR20
TO2
00H
01H
FFH 00H
01H
N
M
N + 1
N
FFH 00H
02H
FFH 00H
M – 1 M
01H
N
00H
00H
01H