11. Bus; Introduction; Registers - Renesas M16C/64A Series User Manual

M16C/64A Group

11. Bus

11.1

Introduction

Two types of buses are available:
•
Internal bus in the MCU
•
External bus which is used to access to external devices in memory expansion mode or
microprocessor mode
Table 11.1 Bus Specifications
Item
•
Used in all processor modes
•
Separate bus
Internal bus
•
16-bit data bus width
•
0 or 1 software waits can be inserted
•
Used in memory expansion mode or microprocessor mode
•
Separate bus or multiplexed bus selectable
•
Data bus width selectable (8 or 16 bits)
•
Number of address buses selectable (12, 16, or 20 buses)
4 chip select outputs CS0 to CS3
•
Combinations of read and write signals selectable ( RD , BHE , WR or RD , WRL , WRH )
External bus •
RDY available
•
•
0 to 3 software waits can be inserted
•
Memory area expansion function (up to 4 MB) (refer to 12. "Memory Space Expansion
Function")
•
3 V or 5 V interface
11.2

Registers

Table 11.2 lists bus related registers. Refer to 10. "Processor Mode" for registers PM0 and PM1. Refer to
30. "Flash Memory" for the FMR1 register.
Table 11.2 Registers
Address
0004h Processor Mode Register 0
0005h Processor Mode Register 1
0008h Chip Select Control Register
001Bh Chip Select Expansion Control Register
0221h Flash Memory Control Register 1
R01UH0136EJ0210 Rev.2.10
Jul 31, 2012
Specification
Register Symbol Reset Value
0000 0000b
(CNVSS pin is low)
PM0
0000 0011b
(CNVSS pin is high)
PM1 0000 1000b
CSR
CSE
FMR1 00X0 XX0Xb
11. Bus
01h
00h
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