Programming Model

The command and data RAM in the QSPI are indirectly accessible with QDR and QAR as 48 separate locations that comprise 16 words of transmit data, 16 words of receive data, and 16 bytes of commands.

A write to QDR causes data to be written to the RAM entry specified by QAR[ADDR]. This also causes the value in QAR to increment.

Correspondingly, a read at QDR returns the data in the RAM at the address specified by QAR[ADDR]. This also causes QAR to increment. A read access requires a single wait state.

NOTE

The QAR does not wrap after the last queue entry within each section of the RAM. The application software must handle address range errors.

22.5.5 QSPI Address Register (QAR)

The QAR, shown in Figure 22-8,is used to specify the location in the QSPI RAM that read and write operations affect.

Field

Reset

R/W Address

15

6

5

0

 

 

ADDR

 

 

 

 

0000_0000_0000_0000

R/W

IPSBAR + 0x350

Figure 22-8. QSPI Address Register

22.5.6 QSPI Data Register (QDR)

The QDR, shown in Figure 22-9,is used to access QSPI RAM indirectly. The CPU reads and writes all data from and to the QSPI RAM through this register.

Field

Reset

R/W Address

15

0

DATA

0000_0000_0000_0000

R/W

IPSBAR + 0x354

Figure 22-9. QSPI Data Register (QDR)

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MCF5282 User’s Manual

MOTOROLA

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Motorola MCF5282, MCF5281 user manual Qspi Address Register QAR, Qspi Data Register QDR