Fujitsu MB89950 Series, Руководство по оборудованию

Страница: 165 / 318

151
CHAPTER 8 PULSE WIDTH COUNT TIMER (PWC)
Table 8.3-2 PWC pulse width control register 2 (PCR2) bits
Bit Function
Bit 7 FC:
Operating mode
selection bit • This bit switches between the interval timer function (FC = "0") and pulse width
measurement function (FC = "1").
Note:
When using the pulse width measurement function (FC = "1"), set the P42/PWC/INT1
pin as an input port.
Bit 6 RM:
Reload mode
selection bit • For the interval timer function:
This bit selects reload timer mode (RM = "0") or one-shot timer mode (RM = "1").
• For the pulse width measurement function:
This bit has no meaning.
Bit 5 TO:
Timer output bit • The value of this bit is inverted each time a counter value underflow (01
H
--> 00
H
)
occurs.
• By counting the number of times this bit is inverted (number of underflow (01
H
--> 00
H
)
occurs), pulse widths longer than 2
8
× the cycle of the selected count clock can be
measured.
Bit 4 Unused bit • The read value is indeterminate.
• Writing to this bit has no effect on the operation.
Bit 3
Bit 2 C1, C0:
Count clock
selection bits • These bits select the count clock for the interval timer function and pulse width
measurement function.
• Three internal count clocks can be selected.
Note:
Do not set "11
B
" to C1 and C0 bits.
Bit 1
Bit 0 W1, W0:
Measured pulse
selection bits • For the pulse width measurement function:
These bits select which pulse edges to use as the start and end conditions for pulse
measurement. Four types of pulse width or cycle can be selected.
• For the interval timer function:
These bits have no meaning.
Note:
Do not modify the PCR2 register while the counter is operating (PCR1: EN = "1").