M16C65 Datasheet, PDF (202/829 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M16C/60

Under development
M16C/65 Group
Preliminary Specification
This is a preliminary specification and is subject to change.
11. Bus
11.3.3 External Bus
The external bus is used to access external devices in memory expansion mode or microprocessor
mode.
In memory expansion or microprocessor mode, some pins serve as the bus control pins to perform data
input to and output from external devices. The bus control pins are as follows: A0 to A19, D0 to D15,
CS0 to CS3, RD, WRL /WR, WRH / BHE, ALE, RDY, HOLD, HLDA, and BCLK.
11.3.4 External Bus Mode
Multiplexed bus mode or separate bus mode can be selected using bits PM05 to PM04 in the PM0
register. Table 11.4 shows the Difference between Separate Bus and Multiplexed Bus Modes.
11.3.4.1 Separate Bus
In external bus mode, data and address are separate.
11.3.4.2 Multiplexed Bus
In external bus mode, data and address are multiplexed.
• When input level to the BYTE pin is high (8-bit data bus)
D0 to D7 and A0 to A7 are multiplexed.
• When input level to the BYTE pin is low (16-bit data bus)
D0 to D7 and A1 to A8 are multiplexed. D8 to D15 are not multiplexed (do not use these pins).
External devices connected to a multiplexed bus are assigned only even addresses of the MCU.
Table 11.4 Difference between Separate Bus and Multiplexed Bus Modes
Pin Name ⁽¹⁾
Separate Bus
Multiplexed Bus
BYTE = high
BYTE = low
P0_0 to P0_7/D0 to D7
D0 to D7
(Note 2)
(Note 2)
P1_0 to P1_7/D8 to D15
D8 to D15
I/O port
P1_0 to P1_7
(Note 2)
P2_0/A0 (/ D0 / -)
P2_1 to P2_7/A1 to A7
(/ D1 to D7 / D0 to D6)
A0
A1 to A7
A0
D0
A0
A1 to A7 D1 to D7
A1 to A7 D0 to D6
P3_0/A8 (/ - / D7)
A8
A8
A8
D7
Notes:
1.
2.
See Table 11.9 “Pin Functions for Each Processor Mode”, for bus control signals other than the
above.
Depends on the setting of PM05 and PM04, and area being accessed.
See Table 11.9 “Pin Functions for Each Processor Mode”, for details.
REJ09B0484-0030 Rev.0.30 Sep 09, 2008
Page 167 of 791