System Overview
3-28
Am186™CC/CH/CU Microcontrollers User’s Manual
3.6
BUS INTERFACE
3.6.1
Overview
The Am186CC/CH/CU bus interface controls all accesses to the peripheral control block
(PCB), memory-mapped and I/O-mapped external peripherals, and memory devices. The
bus interface accesses internal peripherals through the PCB. The microcontroller provides
an enhanced bus interface with the following features:
■
Multiplexed address and data bus
■
Nonmultiplexed address bus
■
Option to disable the address phase of the address/data bus for accesses to the upper
(UCS) and/or lower (LCS) memory regions
■
Option to globally disable the address phase of the address/data bus for all memory or
I/O accesses
■
Programmable bus sizing, individually selectable for the upper (UCS) memory space,
lower (LCS) memory space, all non-UCS and non-LCS memory space, and all I/O space
■
Option to boot from an 8-bit device
■
Separate byte write enables for high and low bytes
■
RD signal can act as output enable
■
Bus-mastering support of a PCnet-ISA interface by three-stating additional pins (UCS,
LCS, MCS3–MCS0, PCS7–PCS0, and ALE) during bus-hold
■
Integrated DRAM controller
■
Data Enable/Data Strobe (DEN/DS) and Data Transmit/Receive signal (DT/R) provided
to support an external data bus transceiver and to support a bus interface to 68xxx- style
peripherals
■
Support for the Reset Configuration (RESCON) register used to latch system
configuration information from the AD bus during a power-on reset
■
Peripheral Control Block Relocation (RELOC) register configurable to perform a “dual
decode” of PCB addresses; one address is locked at the default reset location and the
other address depends on how the RELOC register is programmed (default)
UTXDPLS
RSVD_101
O
USB External Transceiver Differential Plus is an output that
drives the external transceiver differential driver plus input.
UXVOE
RSVD_103
O
USB External Transceiver Transmit Output Enable is an
output that enables the external transceiver. UXVOE signals the
external transceiver that USB data is being output by the
microcontroller. When Low this pin enables the transceiver
output, and when High this pin enables the receiver.
UXVRCV
RSVD_104
STI
USB External Transceiver Differential Receiver is a data input
received from the external transceiver differential receiver.
Notes:
1. Icons indicating microcontroller specific signals are used only in the Signal Name column.
Table 3-7
Signal Descriptions (Continued)
Signal Name
1
Multiplexed
Signal(s)
Type Description
CC
CU
CC
CU
CC
CU
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...