M16C User Manual.pdf

Key-Input InterruptMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.13 Key-Input Interrupt2.13.1 OverviewKey-input interrupt occurs when a falling edge is input to P104 through P107. The following is an overviewof the key-input interrupt:(1) Enabling/disabling the key-input interruptThe key-input interrupt can be enabled and disabled using the key-input interrupt register. The keyinputinterrupt is affected by the interrupt priority level (IPL) and the interrupt enable flag (I flag).(2) Occurrence timing of the key-input interruptWith key-input interrupt acceptance enabled, pins P104 through P107, which are set to input, become__________key-input interrupt pins (KI0 through KI3). A key-input interrupt occurs when a falling edge is input to akey-input interrupt pin. At this moment, the level of other key-input interrupt pins must be “H”. Nointerrupt occurs when the level of other key-input interrupt pins is “L”.(3) How to determine a key-input interruptA key-input interrupt occurs when a falling edge is input to one of four pins, but each pin has the samevector address.Therefore, read the input level of pins P104 through P107 in the key-input interrupt routine to determinethe interrupted pin.(4) Registers related to the key-input interruptFigure 2.13.1 shows the memory map of key-input interrupt-related registers, and Figure 2.13.2shows key-input interrupt-related registers.004D16Key input interrupt control register(KUPIC)03F616Port P10 direction register (PD10)03FE16Pull-up control register 2 (PUR2)Figure 2.13.1. Memory map of key-input interrupt-related registers434