NEC PD78P214 Manuale Utente
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PD78214 Sub-Series
(3) With an in-circuit emulator, digital noise cannot be removed correctly. When the timer/counter is used
together with edge detection function, note the point below.
• When IE-78210-R is used
All functions are performed on an erroneously detected edge.
• When other in-circuit emulators are used
When 8-bit timer/counter 2 is used as an external event counter, an erroneously detected edge changes the
timing of coincidence-based interrupt generation. As the result, an interrupt is repeatedly generated at a
time when the value of the timer/counter does not coincide with the value of the compare register.
timing of coincidence-based interrupt generation. As the result, an interrupt is repeatedly generated at a
time when the value of the timer/counter does not coincide with the value of the compare register.
Normal coincidence-based interrupt generation is resumed when the timer/counter is stopped.
Timer output is not affected by an erroneously detected edge, but is performed with the normal timing.
For details of erroneous edge detection, see Section 11.4.
When using an in-circuit emulator, see also Section 7.5.4.
(4) The value of the CR22 register, after being read, becomes undefined. A captured value can be used more than
once by saving the captured value to a register or memory.
7.5.4 Notes on Using In-Circuit Emulators
When an in-circuit emulator is used, noise removal operation for INTP0, INTP1, INTP2/CI, and INTP3 may not be
performed normally, thus resulting in noise detected erroneously as an edge. For details of erroneous edge
detection, see Section 11.4. How a timer/counter operates with an erroneously detected edge is described below.
performed normally, thus resulting in noise detected erroneously as an edge. For details of erroneous edge
detection, see Section 11.4. How a timer/counter operates with an erroneously detected edge is described below.
(1) When IE-78210-R is used
All timer/counter-related operations are performed on erroneously detected edges in the same way as on
normal edges.
normal edges.
(2) When other in-circuit emulators are used
(a) Capture operation
Capture operation is not performed on an erroneously detected edge. However, an interrupt is generated
on an erroneously detected edge. The value of a capture register read during interrupt handling
performed on an erroneously detected edge is as follows:
on an erroneously detected edge. The value of a capture register read during interrupt handling
performed on an erroneously detected edge is as follows:
• For CR02 and CR11
Value captured on the immediately preceding normal edge
• For CR22
Undefined value
(b) Clear operation after capture operation (with only 8-bit timer/counter 1 and 8-bit timer/counter 2)
Clear operation is not performed on an erroneously detected edge. After erroneous edge detection,
however, an interrupt request to be generated when the value of the timer/counter coincides with the
value of a compare register is generated with the timing not based on the values of the timer/counter and
compare register. This interrupt generation timing is the timing assuming that the timer/counter is
cleared. (See Fig. 7-141.)
however, an interrupt request to be generated when the value of the timer/counter coincides with the
value of a compare register is generated with the timing not based on the values of the timer/counter and
compare register. This interrupt generation timing is the timing assuming that the timer/counter is
cleared. (See Fig. 7-141.)
When a coincidence between the value of 8-bit timer/counter 1 and the value of a compare register is used
as an output trigger for a real-time output port, such a deviated timing is used as an output trigger for the
real-time output port.
as an output trigger for a real-time output port, such a deviated timing is used as an output trigger for the
real-time output port.
The timer output function of 8-bit timer/counter 2 is not affected by an erroneously detected edge, but
operates with the correct timing. Such an interrupt generation timing deviation as described above can
be corrected by the following operations:
operates with the correct timing. Such an interrupt generation timing deviation as described above can
be corrected by the following operations:
• Clear operation on a normal edge
• Clearing bit CEn (n = 1, 2) for the 8-bit timer/counter in timer control register 1 (TMC1) to 0