mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 787

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 21
External Bus Interface (S12XEBIV2)
21.1
This document describes the functionality of the XEBI block controlling the external bus interface.
The XEBI controls the functionality of a non-multiplexed external bus (a.k.a. ‘expansion bus’) in
relationship with the chip operation modes. Dependent on the mode, the external bus can be used for data
exchange with external memory, peripherals or PRU, and provide visibility to the internal bus externally
in combination with an emulator.
21.1.1
The XEBI includes the following features:
21.1.2
Refer to the S12X_MMC section for a detailed description of the MCU operating modes.
Freescale Semiconductor
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Output of up to 23-bit address bus and control signals to be used with a non-muxed external bus
Bidirectional 16-bit external data bus with option to disable upper half
Visibility of internal bus activity
Single-chip modes
The external bus interface is not available in these modes.
Expanded modes
Address, data, and control signals are activated on the external bus in normal expanded mode and
special test mode.
Emulation modes
The external bus is activated to interface to an external tool for emulation of normal expanded mode
or normal single-chip mode applications.
Introduction
Features
Modes of Operation
MC9S12XDP512 Data Sheet, Rev. 2.17
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