UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 287

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

9.5 EXTERNAL EVENT COUNTER FUNCTION
clock is specified as external clock input by the setting of the low-order 4 bits of prescaler mode register 1 (PRM1), TM1 operates
as an external event counter.
sampling clock select register (SCS0) as shown in Table 9-4.
is high or low. If the width is shorter than this, the pulse may not be counted.
(1) Counting one edge (maximum frequency = f
Timer/counter 1 can count clock pulses input from the external interrupt request input pin (INTP0) pin.
No special selection method is needed for the external event counter operating mode. When the timer register 1 (TM1) count
The maximum frequency of the external clock pulse that can be counted by the external event counter is determined by the
The maximum frequency is the same when both the edges of the INTP0 input are counted and when only one edge is counted.
The pulse width of the INTP0 input must be three or more sampling clocks selected by SCS0, regardless of whether the level
Figure 9-10 shows the timing of the external event count by timer/counter 1.
Remarks 1. ICI: INTP0 input signal after passing through edge detection circuit
Table 9-4 Maximum Input Frequency and Minimum Input Pulse Width That Can be Counted as Events
INTP0
TM1
ICI
2. f
Sampling Clock Selected by SCS0
SMP
4/f
Dn
SMP
is selected by the sampling clock selection register (SCS0).
Figure 9-10 Timing of External Event Count by Timer/Counter 1 (1/2)
(MIN.) 4/f
f
f
f
f
CLK
CLK
CLK
CLK/
/64
/128
256
SMP
(MIN.) 8/f
Dn+1
CHAPTER 9 TIMER/COUNTER 1
SMP
(MIN.)
Maximum Input Frequency
CLK
f
f
f
f
CLK
CLK
CLK
CLK
/8)
/8 (1.56 MHz)
/512 (24.4 kHz)
/1024 (12.2 kHz)
/2048 (6.10 kHz)
Dn+2
3–4/f
SMP
( ): f
XX
Minimum Pulse Width
Dn+3
= 25 MHz, f
4/f
256/f
512/f
1024/f
CLK
XX
XX
(0.32 s)
XX
(10.2 s)
(20.5 s)
CLK
(41.0 s)
= 12.5 MHz
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