Freescale-semiconductor i.MX27 PDK 1.0 Bedienungsanleitung PDF herunterladen (Seite 29)

i.MX27 PDK 1.0 Hardware User's Guide, Rev. 1.0 Freescale Semiconductor

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4.3 CPLD on the Debug Board

A complex programmable logic device (CPLD) is an electronic component used to build

reconfigurable digital circuits. The CPLD provides a great deal of functionality, including glue

logic, which is needed to achieve compatible interfaces between two (or more) different

off-the-shelf integrated circuits. For the 3-Stack board, glue logic provides peripheral bus address

decoding, board control and status signals, board revision registers, and other functions, and is

implemented with a CPLD on the Debug board.

4.3.1 CPLD Features

The CPLD provides the following key features:

• A 16-bit slave interface to the CPU data bus

• Address decode and control for the Ethernet controller

• Address decode and control for the external UART controller

• Level shift for Ethernet signals and UART signals

• Control and status registers for various board functions

4.3.2 CPLD Memory Map

Table 4-2 CPLD Memory Map

CS5

A16 A15 A14 A5 A4 A3 A2 Description

0 0 0 0 X X X X SMSC LAN9217 Ethernet 10/100BT

0 0 0 1 X X X X External UART-A

0 0 1 0 X X X X External UART-B

0 0 1 1 X X X X Reserved

0 1 0 0 0 0 0 0 Read/Write LED's (1=on, 0=off)

0 1 0 0 0 0 0 1 Read Only Switches/Buttons

0 1 0 0 0 0 1 0 Read Only Status - Interrupts, Interrupt latch

0 1 0 0 0 0 1 1 Read/Write - Interrupt Mask

0 1 0 0 0 1 0 0 Write - Interrupt reset

0 1 0 0 0 1 0 1 R/W Software Override: Set UART-B/CPU UART

routing

0 1 0 0 0 1 1 0 R/W Software Override: Enable/Disable Flash

Access, select CSx

0 1 0 0 0 1 1 1 Software Override 3 reserved

0 1 0 0 1 0 0 0 Read Only Returns AAAA

0 1 0 0 1 0 0 1 Read Only Returns 5555

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