M16C User Manual.pdf

Programmable I/O PortsMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER(b) Memory expansion mode, microprocessor modeTable 2.15.3. Examples of working on unused pins in memory expansion mode or microprocessor modePin namePorts P6 to P10 (excluding P85)BHE, ALE, HLDAXOUT (Note 4), BCLK (Note 6)HOLD, RDY, NMIAVCCAVSS, VREFConnectionAfter setting for input mode, connect every pin to VSS or VCC via aresistor; or after setting for output mode, leave these pins open.(Note 1, Note 2, Note 5)Open (Note 3)OpenConnect via resistor to VCC (pull-up)Connect to VCCConnect to VSSNote 1:Note 2:Note 3:Note 4:Note 5:Note 6:If setting these pins in output mode and opening them, ports are in input mode until switched intooutput mode by use of software after reset. Thus the voltage levels of the pins become unstable,and there can be instances in which the power source current increases while the ports are ininput mode.In view of an instance in which the contents of the direction registers change due to a runawaygenerated by noise or other causes, setting the contents of the direction registers periodically byuse of software increases program reliability.Make wiring as short as possible (not more than 2 cm from the microcomputer's pins) in workingon non-used pins.When a VSS level is connected to the CNVSS pin, these pins are input ports until the processormode is switched by use of software after reset. Thus the voltage levels of the pins destabilize,and there can be an increase in the power source current while these pins are input ports.When an external clock is input to the XIN pin.Output "L" if port P70 and P71 are set to output mode.Port P70 and P71 are N channel open drain.When the BCLK output disable bit (bit 7 at address 000416) is set to “1”, connect to VCC via aresistor (pull-up).448