UPD78F0138 NEC, UPD78F0138 Datasheet - Page 172

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

(4) Pulse width measurement by means of restart
172
CR01n capture value
CR00n capture value
TM0n count value
Note Clear OVF0n by software.
When input of a valid edge to the TI00n pin is detected, the count value of 16-bit timer counter 0n (TM0n) is taken
into 16-bit timer capture/compare register 01n (CR01n), and then the pulse width of the signal input to the TI00n
pin is measured by clearing TM0n and restarting the count operation.
Either of two edgesrising or fallingcan be selected using bits 4 and 5 (ES0n0 and ES0n1) of prescaler mode
register 0n (PRM0n).
Sampling is performed using the count clock cycle selected by prescaler mode register 0n (PRM0n) and a
capture operation is only performed when a valid level of the TI00n pin is detected twice, thus eliminating noise
with a short pulse width.
Remark n = 0:
TI00n pin input
Count clock
INTTM01n
OVF0n
Figure 6-28. Timing of Pulse Width Measurement Operation with Free-Running Counter
n = 0, 1:
0000H
µ
µ
t
PD780131, 780132
PD780133, 780134, 78F0134, 780136, 780138, 78F0138
and Two Capture Registers (with Rising Edge Specified)
0001H
CHAPTER 6 16-BIT TIMER/EVENT COUNTERS 00 AND 01
D0
(D1
D0
User’s Manual U16228EJ2V0UD
D0 + 1
D0)
t
D1
D1
D1 + 1
(10000H
FFFFH
D1 + D2)
0000H
t
D2
(D3
D2 + 1
D2
Note
D2)
t
D3
D3