M69KB128AA datasheet(27/68 Pages) STMICROELECTRONICS

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M69KB128AA

7 Configuration registers

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Configuration registers

The M69KB128AA features three registers:

●

The Bus Configuration Register (BCR)

●

The Refresh Configuration Register (RCR)

●

The Device ID Register (DIDR).

BCR and RCR are user-programmable registers that define the device operating mode. They

are automatically loaded with default settings during Power-Up, and selected by address bits

A18 and A19 (see Table 8: Register Selection).

DIDR is a read-only register that contains information about the device identification. It is

selected by setting address bit A18 to ‘1’ with A19 ‘don’t care’ (see Table 8: Register Selection).

The configuration registers (only BCR and RCR) can be programmed and read using two

methods:

●

The CR Controlled Method (or Hardware Method)

●

The Software Method.

7.1

Programming the Registers by the CR controlled method

7.1.1

Read Configuration Register

The content of a register is read by issuing a read operation with Configuration Register Enable

signal, CR, High, VIH. Address bits A18 and A19 select the register to be read (see Table 8:

DQ15.

The BCR, RCR and DIDR can be read either in normal asynchronous or synchronous mode.

The CR pin has to be driven high prior to any access.

See Table 6 and Table 7 for a detailed description of Configuration register Read by the CR

Controlled methods and Figure 17 and Figure 28, CR Controlled Configuration Register Read

waveforms in asynchronous and synchronous mode.

7.1.2

Program Configuration Register

BCR and RCR registers can be programmed by issuing a bus write operation, in asynchronous

or synchronous mode (NOR-Flash or Full Synchronous), with Configuration Register Enable

signal, CR, High, VIH. Address bits A18 and A19 allow to select between BCR and RCR (see

Table 8: Register Selection).

In synchronous mode, the values placed on address lines A0 to A15 are latched on the rising

edge of L, E, or W, whichever occurs first.

In asynchronous mode, a register is programmed by toggling L signal.

LB and UB are ‘don’t care’. The CR pin has to be driven high prior to any access.

Refer to Table 5 and Table 7 for a detailed description of Configuration Register Program by the

CR Controlled method and to Figure 22 and Figure 33, showing CR controlled Configuration

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