NEC PD78214 - Manual (Page 128)

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Chapter 6 Real-Time Output Function
6
6.4 OPERATION
When port 0 is in the real-time output port mode, the contents of the buffer registers (P0H and P0L) are sent to the
output latches for output to the pins of port 0 in synchronization with the occurrence of a trigger condition listed
in Table 6-2.
For example, let’s select, as an output trigger source, a signal (INTC10 or INTC11) indicating that timer 1 (TM1) of
8-bit timer/counter 1 coincides with the compare register (CR10 or CR11). In this case, the output data at the pins
of port 0 can be made to reflect the contents of the buffer register at intervals of a value preset in each compare
register. Combined use of the real-time output port function and the macro service function can output data at
each pin of port 0 sequentially at arbitrary intervals (see Section 12.4 ).
If external interrupt INTP0 is selected as an external output trigger source, data can be output from port 0 in
synchronization with an external event.
Table 6-2 Output Trigger for the Real-Time Output Port (When P0MH = P0ML = 1)
0
1
0
1
Output mode
RTPC register
BYTE EXTR
0
1
8-bit real-time
output
4-bit real-time
output
P0H register P0L register
INTC11
INTC11
INTC10
INTC10/INTP0
INTC10
INTC10/INTP0
Caution With an in-circuit emulator, digital noise cannot be eliminated normally from the INTP0 pin. When it is specified that data transfer
from the buffer register to the output latch be performed according to a signal from the INTP0 pin, data transfer may occur according
to an erroneously detected edge. Keep in mind this characteristic when using the in-circuit emulator.
See the notes in Chapter 11 for details of erroneous detection of edges.