Module Description

22.3.1 Interface and Signals

The module provides access to as many as 15 devices with a total of seven signals: QSPI_Dout, QSPI_Din, QSPI_CLK, QSPI_CS0, QSPI_CS1, QSPI_CS2, and QSPI_CS3.

Peripheral chip-select signals, QSPI_CS[3:0], are used to select an external device as the source or destination for serial data transfer. Signals are asserted at a logic level corresponding to the value of the QSPI_CS[3:0] bits in the command RAM whenever a command in the queue is executed. More than one chip-select signal can be asserted simultaneously.

Although QSPI_CS[3:0] will function as simple chip selects in most applications, up to 15 devices can be selected by decoding them with an external 4-to-16 decoder.

Queue Control

Block

Queue

Pointer

Comparator

End Queue

Pointer

Control Logic

Status

Regs

Control

Regs

Delay

Counter

Internal Bus

System Clock

4

 

 

 

 

 

 

80-Byte

 

 

Done

 

QSPI

 

 

 

 

RAM

 

 

QSPI

 

 

 

QSPI

Address

 

 

 

Data

Register

 

 

 

Register

4

 

 

 

 

 

4

 

 

 

 

Chip

msb

lsb

 

 

Select

8/16 Bit Shift Reg.

 

QSPI_Din

 

 

 

Logic

 

Rx/Tx Data Reg.

 

 

4

 

 

 

Array

 

 

QSPI_Dout

 

Command

 

 

 

 

 

 

 

 

 

4

QSPI_CS[3:0]

 

 

 

 

Divide by 2

 

Baud Rate

 

QSPI_CLK

 

Generator

 

 

 

 

 

Figure 22-1. QSPI Block Diagram

22-2

MCF5282 User’s Manual

MOTOROLA

Page 458
Image 458
Motorola MCF5282, MCF5281 user manual Interface and Signals, Qspi RAM, Qspiclk