M16C/62 Group DATASHEET

Specified address rangeBus ControlMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERBus ControlThe following explains the signals required for accessing external devices and software waits. The signalsrequired for accessing the external devices are valid when the processor mode is set to memory expansionmode and microprocessor mode. The software waits are valid in all processor modes.(1) Address bus/data busThe address bus consists of the 20 pins A0 to A19 for accessing the 1M bytes of address space.The data bus consists of the pins for data I/O. When the BYTE pin is “H”, the 8 ports D0 to D7 functionas the data bus. When BYTE is “L”, the 16 ports D0 to D15 function as the data bus.When a change is made from single-chip mode to memory expansion mode, the value of the addressbus is undefined until external memory is accessed.(2) Chip select signalThe chip select signal is output using the same pins as P44 to P47. Bits 0 to 3 of the chip select controlregister (address 000816) set each pin to function as a port or to output the chip select signal. The chipselect control register is valid in memory expansion mode and microprocessor mode. In single-chipmode, P44 to P47 function as programmable I/O ports regardless of the value in the chip select controlregister._______In microprocessor mode, only CS0 outputs the chip select signal after the reset state has been can-_______ _______celled. CS1 to CS3 function as input ports. Figure 1.12.1 shows the chip select control register.The chip select signal can be used to split the external area into as many as four blocks. Tables 1.12.1and 1.12.2 show the external memory areas specified using the chip select signal.Table 1.12.1. External areas specified by the chip select signals(A product having an internal RAM equal to or less than 15K bytes and a ROM equal to or less than 192K bytes)(Note)Memory spaceexpansion modeProcessor modeMemory expansion modeNormal mode(PM15,14=0,0)Microprocessor modeExpansionmode 1(PM15,14=1,0)Expansionmode 2(PM15,14=1,1)Memory expansion modeMicroprocessor modeMemory expansion modeChip select signalCS0 CS1 CS2 CS33000016 toCFFFF16(640K bytes)3000016 toFFFFF16(832K bytes)0400016 toCFFFF16(816K bytes)0400016 toFFFFF16(1008K bytes)4000016 toBFFFF16(512K bytes X 7 +256K bytes)2800016 to2FFFF16(32K bytes)2800016 to3FFFF16(96K bytes)4000016 toMicroprocessor modeFFFFF16(512K bytes X 8)Note :Be sure to set bit 3 (PM13) of processor mode register 1 to “0”.0800016 to27FFF16(128K bytes)0400016 to07FFF16(16K bytes)33