CHAPTER 5 PORT FUNCTIONS
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(12) A bit manipulation instruction executed to manipulate the port is not executed normally in the pin access mode
(PRDC0 of port read control register (PRDC) = 1). After checking the port, be sure to reset the mode to the normal
mode (PRDC0 = 0).
(13) If an interrupt occurs in the pin access mode (PRDC0 of PRDC = 1), a bit manipulation instruction may be executed
with this mode maintained, causing malfunctioning. Be sure to set the DI status before checking the port.
Do not use a macro service that manipulates the port.
(14) Occurrence of the non-maskable interrupt cannot be prevented in the pin access mode (PRDC0 of PRDC = 1). Take
the following measures by using the program, depending on the system:
Do not manipulate the port in the non-maskable interrupt routine.
Save the level of PRDC.0 at the beginning of the non-maskable interrupt routine, and restore it on returning
execution from the interrupt routine.
(15) Use the CHKL or CHKLA instruction when the PRDC0 bit of PRDC is “0” (normal mode).
(16) The result of comparison by the CHKL or CHKLA instruction always matches, regardless of whether the pin set in
the input port mode is set in the port mode or control mode.
Because the input level of the input-only pin is read when the CHKL or CHKLA instruction is executed, because this
pin does not have an output latch. In other words, executing the CHKL or CHKLA instruction to the input-only pin
is practically invalid, and therefore, do not use the instruction to manipulate such a pin.
(17) To check the output level of a port with some of its bits set in the control output mode and others in the port output
mode, by using the CHKL or CHKLA instruction, execute the instruction after changing the input/output mode of the
control output pin to the input mode (the output level of the control output pin changes asynchronously and therefore
cannot be checked by the CHKL or CHKLA instruction).