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Signal Descriptions

A.5 AXI interface signals

The AXI interface ports operate using standard AXI signals, described in the following sections:

Instruction read port signals

Data port signals on page A-8

Peripheral port signals on page A-9

DMA port signals on page A-10.

Note

All the outputs listed in this section have their reset values during Standby.

Full descriptions of the AXI interface signals are given in the AMBA® AXI Protocol V1.0 Specification. This section only summarizes how the AXI interfaces are implemented on this processor.

The AXI signal names have a one or two-letter suffix that indicate the port, as shown in

Table A-5.

Table A-5 Port signal name suffixes

Port

Suffix

Comment

 

 

 

Instruction fetch

I

Read-only

 

 

 

Data read/write

RW

Read/write

 

 

 

Peripheral

P

Read/write

 

 

 

DMA

D

Read/write

 

 

 

A.5.1 Instruction read port signals

The instruction read port is a 64-bit wide read-only AXI port. The standard AXI read channel signal names are suffixed with I, and the implementation details of the port are:

ARID[3:0] and RID[3:0] signals are not implemented

the read data bus is implemented as RDATAI[63:0]

the ARSIDEBANDI[4:0] output is implemented to indicate shared and inner cacheable accesses.

Table A-6 on page A-8 gives more information about the instruction read port AXI implementation. See the AMBA® AXI Protocol V1.0 Specification for details of the other signals on this port.

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Signal Descriptions

 

 

 

Table A-6 Instruction read port AXI signal implementation

 

 

 

 

Name

Direction

Type

Description

 

 

 

 

ARLENI[3:0]

Output

Read

Burst length that gives the exact number of transfers:

 

 

 

b0000, 1 data transfer

 

 

 

b0001, 2 data transfers

 

 

 

b0010, 3 data transfers

 

 

 

b0011, 4 data transfers, maximum for the instruction read port

 

 

 

 

ARSIZEI[2:0]

Output

Read

Burst size, always set to b011, indicating 64-bit transfer

 

 

 

 

ARBURSTI[1:0]

Output

Read

Burst type:

 

 

 

b01, INCR incrementing burst

 

 

 

b10, WRAP Wrapping burst

 

 

 

 

ARLOCKI[1:0]

Output

Read

Lock type, always set to b00, indicating normal access

 

 

 

 

ARSIDEBANDI[4:0]

Output

-

Indicates accesses to shared and inner cacheable memory

 

 

 

 

A.5.2 Data port signals

The data port is a 64-bit wide read/write AXI port. The standard AXI read channel, write channel, and write response channel signal names are suffixed with RW, and the implementation details of the port are:

AWID[3:0], WID[3:0], BID[3:0], ARID[3:0], and RID[3:0] signals are not implemented

the write data bus is implemented as WDATARW[63:0], and therefore the write strobe signal is implemented as WSTRBRW[7:0]

the read data bus is implemented as RDATARW[63:0]

the ARSIDEBANDRW[4:0] output and AWSIDEBANDRW[4:0] output signals are implemented to indicate shared and inner cacheable accesses

the WRITEBACK output signal is implemented to indicate cache line evictions.

Table A-7 on page A-9 gives more information about the data port AXI implementation. See the AMBA® AXI Protocol V1.0 Specification for details of the other signals on this port.

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Signal Descriptions

 

 

 

Table A-7 Data port AXI signal implementation

 

 

 

 

Name

Direction

Type

Description

 

 

 

 

AWSIZERW[2:0]

Output

Write

Write burst size:

 

 

 

000, 8-bit transfers

 

 

 

001, 16-bit transfers

 

 

 

010, 32-bit transfers

 

 

 

011, 64-bit transfers, maximum for the data port.

 

 

 

 

AWBURSTRW[1:0]

Output

Write

Write burst type:

 

 

 

01, INCR Incrementing burst

 

 

 

10, WRAP Wrapping burst.

 

 

 

 

AWLOCKRW[1:0]

Output

Write

Write lock type:

 

 

 

00, Normal access

 

 

 

01, Exclusive access.

 

 

 

 

ARLENRW[3:0]

Output

Read

Burst length that gives the exact number of transfer:

 

 

 

b0000, 1 data transfer

 

 

 

b0001, 2 data transfers

 

 

 

b0010, 3 data transfers

 

 

 

b0011, 4 data transfers

 

 

 

b0100, 5 data transfers

 

 

 

b0101, 6 data transfers

 

 

 

b0110, 7 data transfers.

 

 

 

 

ARSIZERW[2:0]

Output

Read

Burst size:

 

 

 

b000, indicating 8-bit transfer

 

 

 

b001, indicating 16-bit transfer

 

 

 

b010, indicating 32-bit transfer

 

 

 

b011, indicating 64-bit transfer.

 

 

 

 

ARBURSTRW[1:0]

Output

Read

Burst type:

 

 

 

b01, INCR, Incrementing burst

 

 

 

b10, WRAP, Wrapping burst.

 

 

 

 

ARSIDEBANDRW[4:0]

Output

Read

Indicates read accesses to shared and inner cacheable memory.

 

 

 

 

AWSIDEBANDRW[4:0]

Output

Write

Indicates write accesses to shared and inner cacheable memory.

 

 

 

 

WRITEBACK

Output

-

Indicates that the current transaction is a cache line eviction. This

 

 

 

signal has the same timing as the write address channel signals.

 

 

 

 

A.5.3 Peripheral port signals

The peripheral port is a 32-bit wide read/write AXI port. The standard AXI read channel, write channel, and write response channel signal names are suffixed with P, and the implementation details of the port are:

AWID[3:0], WID[3:0], BID[3:0], ARID[3:0], and RID[3:0] signals are not implemented

the write data bus is implemented as WDATAP[31:0], and therefore the write strobe signal is implemented as WSTRBP[3:0]

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Signal Descriptions

the read data bus is implemented as RDATAP[31:0]

the ARSIDEBANDP[4:0] output and AWSIDEBANDP[4:0] output signals are implemented to indicate shared and inner cacheable accesses. These signals have fixed values.

Table A-8 gives more information about the peripheral port AXI implementation. See the

AMBA® AXI Protocol V1.0 Specification for details of the other signals on this port.

 

 

 

Table A-8 Peripheral port AXI signal implementation

 

 

 

 

Name

Direction

Type

Description

 

 

 

 

AWSIZEP[2:0]

Output

Write

Write burst size:

 

 

 

b000, 8-bit transfers

 

 

 

b001, 16-bit transfers

 

 

 

b010, 32-bit transfers, maximum for the peripheral port.

 

 

 

 

AWBURSTP[1:0]

Output

Write

Write burst type, always set to b01, INCR, Incrementing burst.

 

 

 

 

AWLOCKP[1:0]

Output

Write

Write lock type, always set to b00, Normal access.

 

 

 

 

AWCACHEP[3:0]

Output

Write

Cache type giving additional information about cacheable

 

 

 

characteristics for write accesses. Always set to 0x1.

 

 

 

 

ARLENP[3:0]

Output

Read

Burst length that gives the exact number of transfer:

 

 

 

b0000, 1 data transfer

 

 

 

b0001, 2 data transfers.

 

 

 

 

ARSIZEP[2:0]

Output

Read

Burst size:

 

 

 

b000, 8-bit transfer

 

 

 

b001, 16-bit transfer

 

 

 

b010, 32-bit transfer.

 

 

 

 

ARBURSTP[1:0]

Output

Read

Read burst type, always set to b01, INCR, Incrementing burst.

 

 

 

 

ARLOCKP[1:0]

Output

Read

Lock type:

 

 

 

b00, normal access

 

 

 

b10, locked transfer.

 

 

 

 

ARCACHEP[3:0]

Output

Read

Cache type giving additional information about cacheable

 

 

 

characteristics. Always set to 0x1.

 

 

 

 

ARSIDEBANDP[4:0]

Output

Read

Indicates read accesses to shared and inner cacheable memory.

 

 

 

Always set to 0x2.

 

 

 

 

AWSIDEBANDP[4:0]

Output

Write

Indicates write accesses to shared and inner cacheable memory.

 

 

 

Always set to 0x2.

 

 

 

 

A.5.4 DMA port signals

The DMA port is a 64-bit wide read/write AXI port. The standard AXI read channel, write channel, and write response channel signal names are suffixed with D, and the implementation details of the port are:

AWID[3:0], WID[3:0], BID[3:0], ARID[3:0], and RID[3:0] signals are not implemented

the write data bus is implemented as WDATAD[63:0], and therefore the write strobe signal is implemented as WSTRBD[7:0]

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Signal Descriptions

the read data bus is implemented as RDATAD[63:0]

the ARSIDEBANDD[4:0] output and AWSIDEBANDD[4:0] output signals are implemented to indicate shared and inner cacheable accesses

the WRITEBACK output signal is implemented to indicate cache line evictions.

The DMA port is a 64-bit wide AXI port that is read/write. Table A-9 lists the DMA port signals.

Table A-9 DMA port signals

Name

Direction

Type

Description

 

 

 

 

AWLEND[3:0]

Output

Write

Write burst length:

 

 

 

b0000, 1 data transfer

 

 

 

b0001, 2 data transfers

 

 

 

b0010, 3 data transfers

 

 

 

b0011, 4 data transfers, maximum for the DMA port.

 

 

 

 

AWSIZED[2:0]

Output

Write

Write burst size:

 

 

 

b000, indicating 8-bit transfer

 

 

 

b001, indicating 16-bit transfer

 

 

 

b010, indicating 32-bit transfer

 

 

 

b011, indicating 64-bit transfer.

 

 

 

 

AWBURSTD[1:0]

Output

Write

Write burst type:

 

 

 

b00, FIXED, fixed burst

 

 

 

b01, INCR, incrementing burst.

 

 

 

 

AWLOCKD[1:0]

Output

Write

Write lock type, always set to b00, indicating normal access.

 

 

 

 

ARLEND[3:0]

Output

Read

Burst length that gives the exact number of transfer:

 

 

 

b0000, 1 data transfer

 

 

 

b0011, 4 data transfers.

 

 

 

 

ARSIZED[2:0]

Output

Read

Burst size:

 

 

 

b000, indicating 8-bit transfer

 

 

 

b001, indicating 16-bit transfer

 

 

 

b010, indicating 32-bit transfer

 

 

 

b011, indicating 64-bit transfer.

 

 

 

 

ARBURSTD[1:0]

Output

Read

Burst type:

 

 

 

b00, FIXED, fixed burst

 

 

 

b01, INCR, incrementing burst.

 

 

 

 

ARLOCKD[1:0]

Output

Read

Lock type, always set to b00, indicating normal access.

 

 

 

 

ARSIDEBANDD[4:0]

Output

Read

Indicates read accesses to shared and inner cacheable memory.

 

 

 

 

AWSIDEBANDD[4:0]

Output

Write

Indicates write accesses to shared and inner cacheable memory.

 

 

 

 

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