NEC PD78212, User Manual

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222
µ
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.
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.
(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.
(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:
• 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 .)
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.
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:
• 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