M16C Datasheet, PDF (28/262 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Preliminary Specifications REV.B
Mitsubishi microcomputers
Specifications in this manual are tentative and subject to change.
M16C / 6N Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Bus Control
(4) ALE signal
The ALE signal latches the address when accessing the multiplex bus space. Latch the address when the
ALE signal falls.
When BYTE pin = “H”
ALE
D0/A0 to D7/A7
Address
Data (Note 1)
A8 to A19
Address (Note 2)
When BYTE pin = “L”
ALE
A0
Address
D0/A1 to D7/A8
Address
Data (Note 1)
A9 to A19
Address
Note 1: Floating when reading.
Note 2: When multiplexed bus for the entire space is selected, these are I/O ports.
Figure 3-6. ALE sigal and address/data bus
(5) Ready signal
The ready signal facilitates access of external devices that require a long time for access. As shown in
Figure 3-7, inputting “L” to the RDY pin at the falling edge of BCLK causes the microcomputer to enter the
ready state. Inputting “H” to the RDY pin at the falling edge of BCLK cancels the ready state. Table 3-6
shows the microcomputer status in the ready state. Figure 3-7 shows the example of the RD signal being
extended using the RDY signal.
Ready is valid when accessing the external area during the bus cycle in which the software wait is applied.
Table 3-6. Microcomputer status in ready state (Note)
Item
Oscillation
Status
On
R/W signal, address bus, data bus, CS
ALE signal, HLDA, programmable I/O ports
Internal peripheral circuits
Maintain status when ready signal received
On
Note: The ready signal cannot be received immediately prior to a software wait.
BCLK
RD
CSi
(i = 0 to 3)
RDY
tsu (RDY – BCLK)
Figure 3-7. Example of RD signal extended by RDY signal
28
: Wait using ready function
: Wait using software