Z86L78 Datasheet, PDF (36/59 Pages) Zilog, Inc. – IR/Low-Voltage Microcontroller

Z86L78
IR/Low-Voltage Microcontroller
Zilog
FUNCTIONAL DESCRIPTION (Continued)
Ping-Pong Mode
This operation mode is only valid in Transmit Mode. T8
and T16 need to be programmed in Single-Pass Mode
(CTR0 D6, CTR2 D6) and Ping-Pong Mode needs to be
programmed in CTR1 D3, D2. The user can begin the op-
eration by enabling either T8 or T16 (CTR0 D7 or CTR2
D7). For example, if T8 is enabled, T8_OUT is set to this
initial value (CTR1 D1). According to T8_OUT's level,
TC8H or TC8L is loaded into T8. After the terminal count
is reached, T8 is disabled and T16 is enabled. T16_OUT
switches to its initial value (CTR1 D0), data from TC16H
and TC16L is loaded, and T16 starts to count. After T16
reaches the terminal count it stops, T8 is enabled again,
and the whole cycle repeats. Interrupts can be allowed
when T8 or T16 reaches terminal control (CTR0 D1, CTR2
D1). To stop the Ping-Pong operation, write 00 to bits D3
and D2 of CTR1.
Note: Enabling Ping-Pong operation while the
counter/timers are running may cause intermittent
counter/timer function. Therefore, disable the
counter/timers, then reset the status flags prior to institut-
ing this operation.
Enable
TC8
Time-Out
Enable
TC16
Time-Out
Figure 27. Ping-Pong Mode
Ping-Pong
CTR1 D3,D2
To Initiate Ping-Pong Mode
First, make sure both counter/timers are not running. Then
set T8 into Single-Pass Mode (CTR0 D6), set T16 into Sin-
gle-Pass Mode (CTR2 D6), and set Ping-Pong Mode
(CTR1 D2, D3). These instructions do not have to be in
any particular order. Finally, start Ping-Pong Mode by en-
abling either T8 (CTR0 D7) or T16 (CTR2 D7).
During Ping-Pong Mode
The enable bits of T8 and T16 (CTR0 D7, CTR2 D7) will
be cleared by hardware. The time-out bits (CTR0 D5,
CTR2 D5) will be set every time the counter/timers reach
the terminal count.
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DS97LVO0701