PSD4235G2 datasheet(40/89 Pages) STMICROELECTRONICS

40 / 89 page

PSD4235G2

40/89

MCU BUS INTERFACE

The “no-glue logic” MCU Bus Interface block can

be directly connected to most popular MCUs and

their control signals. Key 16-bit MCUs, with their

bus types and control signals, are shown in Table

34. The MCU interface type is specified using the

PSDsoft Express.

PSD Interface to a Multiplexed Bus. Figure 19

shows an example of a system using a MCU with

a 16-bit multiplexed bus and a PSD4235G2. The

ADIO port on the PSD is connected directly to the

MCU address/data bus. Address Strobe (ALE/AS,

PD0) latches the address signals internally.

Latched addresses can be brought out to Port E, F

or G. The PSD drives the ADIO data bus only

when one of its internal resources is accessed and

Read Strobe (RD, CNTL1) is active. Should the

system address bus exceed sixteen bits, Ports A,

B, C, or F may be used as additional address in-

puts.

PSD Interface to a Non-Multiplexed 8-Bit Bus.

Figure 20 shows an example of a system using a

MCU with a 16-bit non-multiplexed bus and a

PSD4235G2. The address bus is connected to the

ADIO Port, and the data bus is connected to Ports

F and G. Ports F and G are in tri-state mode when

the PSD is not accessed by the MCU. Should the

system address bus exceed sixteen bits, Ports A,

B, or C may be used for additional address inputs.

Table 34. MCUs and their Control Signals

Note: 1. Unused CNTL2 pin can be configured as CPLD input. Other unused pins (PD3-PD0, PF3-PF0) can be configured for other I/O func-

tions.

2. ALE/AS input is optional for MCUs with a non-multiplexed bus

MCU

CNTL0

CNTL1

CNTL2

PD3

PD02

ADIO0

PF3-PF0

68302, 68306, MMC2001

R/W

LDS

UDS

(Note 1)

—

(Note 1)

68330, 68331, 68332, 68340

R/W

SIZ0

(Note 1)

68LC302, MMC2001

WEL

—WEH

—

(Note 1)

68HC16

R/W

SIZ0

(Note 1)

68HC912

R/W

LSTRB

DBE

EA0

(Note 1)

68HC812 3

R/W

LSTRB

(Note 1)

80196

BHE

(Note 1)

ALE

(Note 1)

80196SP

WRL

(Note 1)

WRH

ALE

(Note 1)

80186

BHE

(Note 1)

ALE

(Note 1)

80C161, 80C164-80C167

BHE

(Note 1)

ALE

(Note 1)

80C51XA

WRL

PSEN

WRH

ALE

A4/D0

A3-A1

H8/300

WRL

(Note 1)

WRH

—

M37702M2

R/W

BHE

(Note 1)

ALE

(Note 1)

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