Altera MAX 10 Embedded Memory Manuel d'utilisateur télécharger pdf (Page 7)

If you... ...Then

• Activate the read enable during a write

operation, or

• Do not create a read-enable signal

The output port shows:

• the new data being written,

• the old data at that address, or

• a “Don't Care” value when read-during-write

occurs at the same address location.

Read-During-Write

The read-during-write operation occurs when a read operation and a write operation target the same

memory location at the same time.

The read-during-write operation operates in the following ways:

• Same-port

• Mixed-port

Related Information

Customize Read-During-Write Behavior on page 3-1

Byte Enable

• Memory block that are implemented as RAMs support byte enables.

• The byte enable controls mask the input data, so that only specific bytes of data are written. The

unwritten bytes retain the values written previously.

• The write enable (wren) signal, together with the byte enable (byteena) signal, control the write

operations on the RAM blocks. By default, the byteena signal is high (enabled) and only the wren

signal controls the writing.

• The byte enable registers do not have a clear port.

• M9K blocks support byte enables when the write port has a data width of ×16, ×18, ×32, or ×36 bits.

• Byte enables operate in a one-hot fashion. The LSB of the byteena signal corresponds to the LSB of the

data bus. For example, if byteena = 01 and you are using a RAM block in ×18 mode, data[8:0] is

enabled and data[17:9] is disabled. Similarly, if byteena = 11, both data[8:0] and data[17:9] are

enabled.

• Byte enables are active high.

Byte Enable Controls

Table 2-1: M9K Blocks Byte Enable Selections

byteena[3:0]

Affected Bytes. Any Combination of Byte Enables is Possible.

datain x 16 datain x 18 datain x 32 datain x 36

[0] = 1 [7:0] [8:0] [7:0] [8:0]

[1] = 1 [15:8] [17:9] [15:8] [17:9]

[2] = 1 — — [23:16] [26:18]

[3] = 1 — — [31:24] [35:27]

UG-M10MEMORY

2015.05.04

Read-During-Write

2-3

MAX 10 Embedded Memory Architecture and Features

Altera Corporation

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Altera MAX 10 Embedded Memory Manuel d'utilisateur Page 7

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