M69KB128AA datasheet(31/68 Pages) STMICROELECTRONICS

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M69KB128AA

7 Configuration registers

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7.3.6

Driver Strength Bits (BCR5-BCR4)

The Driver Strength bits allow to set the output drive strength to adjust to different data bus

loading. Normal driver strength (full drive) and reduced driver strength (half drive and a quarter

drive) are available.

By default, outputs are configured at ‘half drive” strength.

7.3.7

Burst Wrap Bit (BCR3)

Burst Read operations can be confined inside the 4, 8, 16 or 32 Word boundary (wrap) or

allowed to step across the boundary (no wrap). The Burst Wrap bit is used to select between

‘wrap’ and ‘no wrap’. If the Burst Wrap bit is set to ‘1’ (no wrap), the device outputs data

sequentially regardless of burst boundaries. When Continuous Burst operation is selected, the

internal address switches to 000000h if the read address passes the last address. By default,

Burst wrap is disabled (see also Table 10: Burst Type Definition).

7.3.8

Burst Length Bits (BCR2-BCR0)

The Burst Length bits set the number of Words to be output or input during a Synchronous

Burst Read or Write operation. They can be set for 4 Words, 8 Words, 16 Words, 32 Words or

Continuous Burst (default settings), where all the Words are output or input sequentially

regardless of address boundaries (see also Table 10: Burst Type Definition).

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