Z86L825 Datasheet, PDF (53/79 Pages) Zilog, Inc. – 20-Pin Low-Voltage IR Microcontrollers

Z86L825/826/827
20-Pin Low-Voltage IR Microcontrollers
46
TC8H Counts
Counter Enable Command,
T8_OUT switches to its
initial value (CTR1 D1)
T8_OUT toggles
Time-out Interrupt
Figure 34. T8_OUT in Single-Pass Mode
T8_OUT Toggles
T8_OUT TC8L TC8H TC8L TC8H TC8L
Counter Enable Command,
T8_OUT switches to its
initial value (CTR1 D1)
Time-out
Interrupt
Time-out
Interrupt
Figure 35. T8_OUT in Modulo-N Mode
You can modify the values in TC8H or TC8L at any time. The new values take
effect when they are loaded. To ensure known operation, do not write these regis-
ters at the time the values are to be loaded into the counter/timer. An initial count of
1 is not allowed (a nonfunction occurs). An initial count of 0 causes TC8 to count from
0 to FFh to FEh.
Note: “h” is used for hexadecimal values.
Transition from 0 to FFh is not a time-out condition.
Caution: Do not use the same instructions for stopping the counter/
timers and setting the status bits.
Two successive commands are necessary. First, the counter/timers must be
stopped, and second, the status bits must be reset. These commands are
required because it takes one counter/timer clock interval for the initiated event to
actually occur.
T8 Demodulation Mode
You need to 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 comple-
mented and put into one of the capture registers. If it is a positive edge, data is put
PS008808-1203
PRELIMINARY