Chapter 6 8-bit timer/event counters 00 and 01 – NEC switch User Manual
Page 79
User’s Manual U12978EJ3V0UD
79
CHAPTER 6 8-BIT TIMER/EVENT COUNTERS 00 AND 01
6.1 Functions of 8-Bit Timer/Event Counters 00 and 01
The 8-bit timer/event counters (TM00 and TM01) have the following functions.
• Interval timer (TM00 and TM01)
• External event counter (TM01 only)
• Square wave output (TM01 only)
The
µPD789800 Subseries is provided with a 1-channel (TM01) 8-bit timer/event counter and a 1-channel (TM00)
8-bit timer. When reading the description of TM00, “timer/event counter” should be read as “ timer”.
(1) 8-bit interval timer
When the 8-bit timer/event counter is used as an interval timer, it generates an interrupt at any preset time
interval.
Table 6-1. Interval Time of 8-Bit Timer 00
Minimum Interval Time
Maximum Interval Time
Resolution
2
6
/f
X
(10.7
µs)
2
14
/f
X
(2.73 ms)
2
6
/f
X
(10.7
µs)
2
9
/f
X
(85.3
µs)
2
17
/f
X
(21.8 ms)
2
9
/f
X
(85.3
µs)
Remarks 1. f
X
: System clock oscillation frequency
2. The parenthesized values apply to operation at f
X
= 6.0 MHz.
Table 6-2. Interval Time of 8-Bit Timer/Event Counter 01
Minimum Interval Time
Maximum Interval Time
Resolution
2
4
/f
X
(2.67
µs)
2
12
/f
X
(682.7
µs)
2
4
/f
X
(2.67
µs)
2
8
/f
X
(42.7
µs)
2
16
/f
X
(10.9 ms)
2
8
/f
X
(42.7
µs)
Remarks 1. f
X
: System clock oscillation frequency
2. The parenthesized values apply to operation at f
X
= 6.0 MHz.
(2) External event counter
The number of pulses of an externally input signal can be measured.