Operation

16 bytes of commands.

A write to QDR causes data to be written to the RAM entry specified by QAR[ADDR] and 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.

Relative Address

Register

 

 

0x00

QTR0

 

 

0x01

QTR1

 

 

.

.

.

.

.

.

 

 

0x0F

QTR15

 

 

Function

Transmit RAM

16 bits wide

0x10

QRR0

 

 

0x11

QRR1

 

 

.

.

.

.

.

.

 

 

0x1F

QRR15

 

 

Receive RAM

16 bits wide

0x20

QCR0

 

 

0x21

QCR1

 

 

.

.

.

.

.

.

 

 

0x2F

QCR15

 

 

Command RAM

8 bits wide

Figure 22-2. QSPI RAM Model

22.4.1.1Receive RAM

Data received by the QSPI is stored in the receive RAM segment located at 0x10 to 0x1F in the QSPI RAM space. The user reads this segment to retrieve data from the QSPI. Data words with less than 16 bits are stored in the least significant bits of the RAM. Unused bits in a receive queue entry are set to zero upon completion of the individual queue entry.

QWR[CPTQP] shows which queue entries have been executed. The user can query this field to determine which locations in receive RAM contain valid data.

MOTOROLA

Chapter 22. Queued Serial Peripheral Interface (QSPI) Module

22-5

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Motorola MCF5281, MCF5282 user manual Receive RAM, Relative Address Register 0x00, 0x01, 0x0F