NEC PD78212, User Manual

Page: 234 / 487

205
Chapter 7 Timer/Counter Units
7
7.4 8-BIT TIMER/COUNTER 3
7.4.1 Functions
Eight-bit timer/counter 3 can be used as an interval timer, and also as a counter for generating a clock signal used
with the baud rate generator.
When operating as an interval timer, 8-bit timer/counter 3 generates an internal interrupt at specified intervals.
Table 7-19 indicates the interval setting range.
Table 7-19 Intervals of 8-Bit Timer/Counter 3
Resolution
8/f
CLK
(1.3
µ
s)
16/f
CLK
(2.6
µ
s)
32/f
CLK
(5.3
µ
s)
64/f
CLK
(10.7
µ
s)
128/f
CLK
(21.3
µ
s)
256/f
CLK
(42.7
µ
s)
512/f
CLK
(85.3
µ
s)
Maximum interval
2
8
×
8/f
CLK
(341
µ
s)
2
8
×
16/f
CLK
(683
µ
s)
2
8
×
32/f
CLK
(1.37 ms)
2
8
×
64/f
CLK
(2.73 ms)
2
8
×
128/f
CLK
(5.46 ms)
2 8
×
256/f
CLK
(10.9 ms)
2
8
×
512/f
CLK
(21.8 ms)
Minimum interval
8/f
CLK
(1.3
µ
s)
16/f
CLK
(2.6
µ
s)
32/f
CLK
(5.3
µ
s)
64/f
CLK
(10.7
µ
s)
128/f
CLK
(21.3
µ
s)
256/f
CLK
(42.7
µ
s)
512/f
CLK
(85.3
µ
s)
The values in parentheses are based on f
CLK
= 6 MHz.
7.4.2 Configuration
Eight-bit timer/counter 3 consists of one 8-bit timer 3 (TM3) and one 8-bit compare register (CR30).
Fig. 7-122 shows the block diagram of 8-bit timer/counter 3.