Two Capture Registers (With Rising Edge Specified) - NEC 78K0 User Manual

(3) Pulse width measurement with free-running counter and two capture registers
When 16-bit timer counter 0n (TM0n) is operated in free-running mode, it is possible to measure the pulse width
of the signal input to the TI00n pin.
When the rising or falling edge specified by bits 4 and 5 (ES0n0 and ES0n1) of prescaler mode register 0n
(PRM0n) is input to the TI00n pin, the value of TM0n is taken into 16-bit timer capture/compare register 01n
(CR01n) and an interrupt request signal (INTTM01n) is set.
Also, when the inverse edge to that of the capture operation is input into CR01n, the value of TM0n is taken into
16-bit timer capture/compare register 00n (CR00n).
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.
Figure 7-27. Control Register Settings for Pulse Width Measurement with Free-Running Counter and
7
TMC0n 0
7
CRC0n 0
ES1n1
PRM0n 0/1
Remark 0/1: Setting 0 or 1 allows another function to be used simultaneously with pulse width measurement.
See the description of the respective control registers for details.
µ
n = 0: PD780143, 780144
µ
n = 0, 1: PD780146, 780148, 78F0148
196
CHAPTER 7 16-BIT TIMER/EVENT COUNTERS 00 AND 01

Two Capture Registers (with Rising Edge Specified)

(a) 16-bit timer mode control register 0n (TMC0n)
6 5 4 TMC0n3 TMC0n2
0 0 0 0
(b) Capture/compare control register 0n (CRC0n)
6 5 4 3 CRC0n2
0 0 0 0
(c) Prescaler mode register 0n (PRM0n)
ES1n0 ES0n1 ES0n0 3
0/1 0 1 0
User's Manual U15947EJ2V0UD
TMC0n1 OVF0n
1 0/1 0
Free-running mode
*
CRC0n1 CRC0n0
1 1 1
CR00n used as capture register
Captures to CR00n at inverse edge
to valid edge of TI00n.
CR01n used as capture register
2 PRM0n1 PRM0n0
0 0/1 0/1
Selects count clock (setting "11" is prohibited).
Specifies rising edge for pulse width detection.
Setting invalid (setting "10" is prohibited.)