Z86D990 Datasheet, PDF (56/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
49
Note: Do not use the same instructions for stopping the counter/
timers and setting the status bits. Two successive commands
are necessary—the first command for stopping counter/timers
and the second command for resetting the status bits—
because one counter/timer clock interval must complete for the
initiated event to actually occur.
T8 Demodulation Mode
Program TC8L and TC8H to FFh. After T8 is enabled, when the first edge (rising,
falling, or both, depending on CTR1 D5, D4) is detected, it starts to count down.
When a subsequent edge (rising, falling, or both, depending on CTR1 D5, D4) is
detected during counting, the current value of T8 is one’s complemented and put
into one of the capture registers. If T8 is a positive edge, data is placed in LO8. If
T8 is a negative edge, data is placed in H18. One of the edge-detect status bits
(CTR1 D1, D0) is set, and an interrupt can be generated if enabled (CTR0 D2).
Meanwhile, T8 is loaded with TC8H and starts counting again. If T8 reaches 0, the
time-out status bit (CTR0 D5) is set, and an interrupt can be generated if enabled
(CTR0 D1), and T8 continues counting from FFh (see Figure 35).
PS003807-1002
PRELIMINARY