Atmel AT85DVK-07 Spezifikationen PDF herunterladen (Seite 172)

172

AT85C51SND3Bx

7632A–MP3–03/06

Table 193. Device Selection Allowed Configuration

“Read” Session A “read” session is launched and the DFC flow control is enabled. When processing the

spare zone, its information will be checked.

“Write” Session A “write” session is launched and the DFC flow control is enabled. When processing the

spare zone, its information will be set.

NFCE Signal Force Low The 512B-pages memories need to keep asserted the NFCE line during the access time

of a data. This can be done by setting the CELOW bit. In this case, the

NFCEx signal

selected by the last ‘device select’ action is asserted (

NFCE[DEV]= L).

If a new ‘device select’ action occurs while the CELOW bit is set, the NFCEx signal of

the old selected device is de-asserted (

NFCE[OLD_DEV]= H), and the NFCEx signal of

the new one is asserted (

NFCE[NEW_DEV]= L).

Clearing the CELOW bit does not force the NFCE signal high:

• The NFCE signal is automatically asserted at the beginning of the execution of any

new commands.

• The NFCE signal is automatically de-asserted at the completion of the commands.

Data Transfer Stop This action stops the NFC when the data transfer is finished. In this case, the controller

state becomes “not running” (NFRUN bit cleared). This can also be used as an abort

signal in streaming mode.

Column Address Extension The 512B-pages memories have different kind of read commands (00h, 01h, 50h)

depending the data zone that need to be processed (1st half, 2nd half or spare). The

column address given is relative to the zone chosen by the read command. The NFC

needs to have the absolute column address to stop automatically at the end of the page.

The column address extension is given thanks to that command. A9:8 holds the address

extension.

• 00h selects the 1st half zone, i.e. the 0-255 range in the data zone. This is the

default value. A read or a write in NFADC resets A9:8 to 00h.

• 01h selects the 2nd half zone, i.e. the 256-511 range in the data zone.

• 10h selects the spare zone, i.e. the 512-527 range in the data zone.

SMCEN NUMDEV Allowed DEV Comment

0 0

1 0, 1

2 0, 1, 2

3 0, 1, 2, 3

0 3 (SMC) No NF memory is selected

1 3 (SMC), 0

2 3 (SMC), 0, 1

The SMLCK signal can not be used in this configuration,

the SMLCK bit is irrelevant.

3 3 (SMC), 0, 1, 2

Neither SMLCK nor SMINS signals can be used in this

configuration. SMCD and SMLCK bits have an irrelevant

value. SMCTE shall be cleared.

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