SC312XDP512F0MPVR datasheet(792/1348 Pages) FREESCALE

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Chapter 21 External Bus Interface (S12XEBIV2)

MC9S12XDP512 Data Sheet, Rev. 2.21

794

Freescale Semiconductor

21.4

Functional Description

This section describes the functions of the external bus interface. The availability of external signals and

functions in relation to the operating mode is initially summarized and described in more detail in separate

sub-sections.

21.4.1

Operating Modes and External Bus Properties

A summary of the external bus interface functions for each operating mode is shown in Table 21-7.

Table 21-7. Summary of Functions

Properties

(if Enabled)

Single-Chip Modes

Expanded Modes

Normal

Single-Chip

Special

Single-Chip

Normal

Expanded

Emulation

Single-Chip

Emulation

Expanded

Special

Test

Timing Properties

PRR access1

1 Incl. S12X_EBI registers

2 cycles

read internal

write internal

2 cycles

read internal

write internal

2 cycles

read internal

write internal

2 cycles

read external

write int & ext

2 cycles

read external

write int & ext

2 cycles

read internal

write internal

Internal access

visible externally

——

—

1 cycle

External

address access

and

unimplemented area

access2

2 Refer to S12X_MMC section.

—

Max. of 2 to 9

programmed

cycles

or n cycles of

ext. wait3

3 If EWAITE = 1, the minimum number of external bus cycles is 3.

1 cycle

Max. of 2 to 9

programmed

cycles

or n cycles of

ext. wait3

1 cycle

Flash area

address access4

4 Available only if conﬁgured appropriately by ROMON and EROMON (refer to S12X_MMC section).

—

1 cycle

Signal Properties

Bus signals

—

ADDR[22:1]

DATA[15:0]

ADDR[22:20]/A

CC[2:0]

ADDR[19:16]/

IQSTAT[3:0]

ADDR[15:0]/

IVD[15:0]

DATA[15:0]

ADDR[22:20]/A

CC[2:0]

ADDR[19:16]/

IQSTAT[3:0]

ADDR[15:0]/

IVD[15:0]

DATA[15:0]

ADDR[22:0]

DATA[15:0]

Data select signals

(if 16-bit data bus)

——

UDS

LDS

ADDR0

LSTRB

ADDR0

LSTRB

ADDR0

LSTRB

Data direction signals

—

R/WR/WR/W

External wait

feature

——

EWAIT

—

EWAIT

—

Reduced input

threshold enabled on

—

Refer to

Table 21-3

DATA[15:0]

EWAIT

DATA[15:0]

EWAIT

Refer to

Table 21-3

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