Control Register Settings For Measurement Of Two Pulse Widths With Free-Running Counter - NEC 78K0 User Manual

(2) Measurement of two pulse widths with free-running counter
When 16-bit timer counter 0n (TM0n) is operated in free-running mode, it is possible to simultaneously measure
the pulse widths of the two signals input to the TI00n pin and the TI01n pin.
When the 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 edge specified by bits 6 and 7 (ES1n0 and ES1n1) of PRM0n is input to the TI01n pin, the value
of TM0n is taken into 16-bit timer capture/compare register 00n (CR00n) and an interrupt request signal
(INTTM00n) is set.
Specify both the rising and falling edges as the edges of the TI00n and TI01n pins, by using bits 4 and 5 (ES0n0
and ES0n1) and bits 6 and 7 (ES1n0 and ES1n1) of 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 or TI01n pin is detected twice, thus
eliminating noise with a short pulse width.
Figure 7-25. Control Register Settings for Measurement of Two Pulse Widths with Free-Running Counter
7 6
TMC0n 0 0
7 6
CRC0n 0 0
ES1n1 ES1n0 ES0n1
PRM0n 1 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
194
CHAPTER 7 16-BIT TIMER/EVENT COUNTERS 00 AND 01
(a) 16-bit timer mode control register 0n (TMC0n)
5 4 TMC0n3 TMC0n2 TMC0n1
0 0 0 1 0/1
(b) Capture/compare control register 0n (CRC0n)
5 4 3 CRC0n2 CRC0n1
0 0 0 1 0
(c) Prescaler mode register 0n (PRM0n)
ES0n0 3 2 PRM0n1
1 1 0 0 0/1
User's Manual U15947EJ2V0UD
OVF0n
0
Free-running mode
*
CRC0n0
1
CR00n used as capture register
Captures valid edge of TI01n pin to CR00n.
CR01n used as capture register
PRM0n0
0/1
Selects count clock (setting "11" is prohibited).
Specifies both edges for pulse width detection.
Specifies both edges for pulse width detection.