Epson E0C6001, Техническое руководство

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CHAPTER 4: SUMMARY OF PROGRAMMING POINTS
II-51
• Input Port – When modifying the input port from high level to low level
with pull-down resistance, a delay will occur at the rise of
the waveform due to time constant of the pull-down
resistance and input gate capacities. Provide appropriate
waiting time in the program when performing input port
reading.
– Input interrupt programing related precautions
When the content of the mask register is rewritten, while
the port K input is in the active status. The input interrupt
factor flag is set at
➀
.
When using an input interrupt, if you rewrite the content
of the mask register, when the value of the input terminal
which becomes the interrupt input is in the active status
(input terminal = high status), the factor flag for input
interrupt may be set.
For example, a factor flag is set with the timing of
➀
shown in Figure 4.1. However, when clearing the content
of the mask register with the input terminal kept in the
high status and then setting it, the factor flag of the input
interrupt is again set at the timing that has been set.
Consequently, when the input terminal is in the active
status (high status), do not rewrite the mask register
(clearing, then setting the mask register), so that a factor
flag will only set at the rising edge in this case. When
clearing, then setting the mask register, set the mask
register, when the input terminal is not in the active
status (low status).
Fig. 4.1
Input interrupt timing
• Output Port
The FOUT and BUZZER output signal may produce
hazards when the output ports R00 and R01 are turned
on or off.
Port K input
Factor flag set Not set
Mask register
Active status
➀