S1C62440/624A0/624C0/62480 TECHNICAL SOFTWARE
EPSON
II-111
CHAPTER 7: SUMMARY OF NOTES
I/O port
(Pxx)
Output port
(Rxx)
When clearing, then setting the mask register, set the
mask register, when the input terminal is not in the
active status (High status).
When an interrupt is triggered at the rising edge of the
input terminal, a factor flag will be set at the timing of
shown in Figure 7.2.1. In this case, when the mask
registers cleared, then set, you should set the mask
register, when the input terminal is in the Low status.
In addition, when the mask register = "1" and the content
of the input relation register is rewritten in the input
terminal active status, an input interrupt factor flag may
be set. Thus, you should rewrite the content of the input
relation register in the mask register = "0" status.
(1) When BZ, BZ, FOUT, FOUT, and PTCLK (DC) are selected
by mask option, a hazard may be observed in the output
waveform when the data of the output register changes.
(2) Because the R00–R03, R10–R13, R20–R23, and R30–R32
(R33) ports gain high impedance during initial reset, be
careful when using them as interface with external de-
vices and the like.
(3) When R33 port is selected for 2 states and DC (PTCLK)
output by mask option, R33 terminal becomes undefined
at initial reset.
(1) When the I/O port is set at output mode, and low imped-
ance load is connected to the port terminal, the data
written and read may differ.
(2) If the state of the I/O port meets all of the following 4
conditions, the reading data will be undefined:
– The input/output mode is set at output mode
– Output specification is set at Nch open drain
– The content of the data register is "1"
– The pull up resistor turned is OFF
(3) When P30–P33 has been set as the output exclusive in
the mask option, a pull up resistor cannot be added even
if the pull up resistor control register PUP3 has been
made "0".