Architectural Overview
Am186™CC/CH/CU Microcontrollers User’s Manual
1-11
input pins. When driven from a timer input pin, the timer is counting the “event” of an input
transition.
The microcontroller also provides a pulse width demodulation (PWD) option so that a
toggling input signal’s Low state and High state durations can be measured.
1.4.3.5
Hardware Watchdog Timer (Chapter 11)
Each of the Am186CC/CH/CU microcontrollers provides a full-featured watchdog timer,
which includes the ability to generate NMIs, reset the microcontroller (except for pinstraps),
and reset the system (assert RESOUT) when the time-out value is reached. The time-out
value is programmable and ranges from 2
10
to 2
26
processor clocks.
The watchdog timer is used to regain control when a system has failed due to a software
error or the failure of an external device to respond in the expected way. Software errors
can sometimes be resolved by recapturing control of the execution sequence through a
watchdog-timer-generated NMI. When an external device fails to respond, or responds
incorrectly, it may be necessary to reset the microcontroller or the entire system, including
external devices. The watchdog timer provides the flexibility to support both NMI and reset
generation.
1.4.4
Memory and Peripheral Interface
Each of the Am186CC/CH/CU microcontrollers includes the following memory and
peripheral interfaces.
1.4.4.1
System Interfaces and Clock Control (Chapter 3)
The microcontroller includes a bus interface to control all accesses to the peripheral control
block (PCB), memory-mapped and I/O-mapped external peripherals, and memory devices.
The bus interface accesses the internal peripherals through the PCB. The bus interface
features programmable bus sizing, separate byte/write enables, and the option to boot from
an 8-bit or 16-bit device.
The industry-standard 80C186 and 80C188 microcontrollers use a multiplexed address
and data (AD) bus. The address is present on the AD bus only during the t
1
clock phase.
The microcontrollers also provide the multiplexed AD bus and in addition, provide a
nonmultiplexed address (A) bus. The A bus provides an address to the system for the
complete bus cycle (t
1
–t
4
).
The microcontroller operates with a V
CC
of 3.3 ± 0.3 V. All the digital signals are capable
of 5-V-tolerant I/O operation.
The processor supports clock rates from 25 MHz to 50 MHz. Commercial and industrial
temperature ratings are available. The CPU can run in 1x, 2x, or 4x mode.
The Am186CC and Am186CU microcontrollers provide separate crystal oscillator inputs
for the USB peripheral controller and the CPU. Flexibility is provided to run the entire device
from a 12- or 24-MHz crystal when the USB is in use. The CPU can run in 1x, 2x, or 4x
mode; the USB can run in 2x or 4x mode.
1.4.4.2
Dynamic Random Access Memory Support (Chapter 6)
To support DRAM, the microcontroller has a fully integrated DRAM controller that provides
a glueless interface to 25-ns to 70-ns Extended Data Out (EDO) DRAM (EDO DRAM is
sometimes called Hyper-Page Mode DRAM). The microcontroller can access up to two
banks of 4-Mbit (256 Kbit x 16 bit) DRAM. The microcontroller does not support Page Mode
DRAM, Fast Page Mode DRAM, Asymmetrical DRAM, or 8-bit wide DRAM. The
microcontroller provides zero-wait state operation at up to 50 MHz with 40-ns DRAM. This
CC
CU
Содержание Am186 CC
Страница 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Страница 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Страница 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Страница 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Страница 39: ...Architectural Overview Am186 CC CH CU Microcontrollers User s Manual 1 15 Figure 1 6 32 Channel Linecard CH CC...
Страница 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Страница 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Страница 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Страница 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Страница 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...