M16C62_M Datasheet, PDF (540/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

External Buses
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
4.2 Data Access
4.2.1 Data Bus Width
If the voltage level input to the BYTE pin is “H”, the external data bus width becomes 8 bits, and P10 (/
D8) through P17 (/D15) can be used as I/O ports (Figure 4.2.1).
If the voltage level input to the BYTE pin is “L”, the external data bus width becomes 16 bits, and P10
(/D8) through P17 (/D15) operate as a data bus (D8 through D15) (Figure 4.2.1).
Bus width : 8-bit (BYTE = “H”)
Microcomputer
P00 to P07
Data bus D0 to D7
External device
P10 to P17
P20 to P27
P30 to P37
P40 to P43
I/O port
Address bus A0 to A15
Address bus A16 to A19 (Note 1)
P44 to P47
P50 to P52
P53 to P57
Chip select CS0 to CS3 (Note 2)
RD, WRL, WRH / RD, BHE, WR (Note 3)
BCLK, HLDA, HOLD, ALE, RDY
Bus width : 16-bit (BYTE = “L”)
Microcomputer
P00 to P07
Data bus D0 to D7
External device
P10 to P17
P20 to P27
P30 to P37
P40 to P43
Data bus D8 to D15
Address bus A0 to A15
Address bus A16 to A19 (Note 1)
P44 to P47
Chip select CS0 to CS3 (Note 2)
P50 to P52
RD, WRL, WRH / RD, BHE, WR (Note 3)
P53 to P57
BCLK, HLDA, HOLD, ALE, RDY
Note 1: Can be switched to I/O port using the port P40 to P43 function select bits of processor mode register 0 (address 000416).
Note 2: When reset, only CS0 outputs a chip select signal. CS1 through CS3 become input ports.
I/O ports can be switched using the CSi output enable bit of the chip select control register (address 000816).
Note 3: The feature can be switched using the R/W mode select bit of processor mode register 0 (address 000416).
Figure 4.2.1. Level of BYTE pin and external data bus width
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