System Overview
Am186™CC/CH/CU Microcontrollers User’s Manual
3-5
The System Configuration (SYSCON) register is typically written once to establish the
proper modes of operation based on the system in which the part is operating. This register
performs the following functions:
■
Enables the data strobe timings on the DEN pin. When the DSDEN bit (bit 13) is set
to 1, data strobe bus mode is enabled, and the DS timing for reads and writes is identical
to the normal read cycle DEN timing. When the DSDEN bit is cleared to 0, the DEN
timing for both reads and writes is normal (i.e., like the original 80C186). The DEN pin
is renamed DS in data strobe bus mode. For more information, see “Bus Interface” on
page 3-28.
■
Enables Pulse Width Demodulation (PWD) mode. For more information about PWD
mode, see Chapter 10, “Programmable Timers.”
■
Disables memory and I/O addresses on the AD15–AD0 bus. For more information, see
“Bus Interface” on page 3-28.
■
Configures HDLC Channel C and D external interfaces. For more information, see
Chapter 15, “High-Level Data Link Control (HDLC).”
■
Disables CLKOUT and forces the pin to drive a zero externally. For more information,
see “Clock Control” on page 3-32.
The Processor Revision Level (PRL) register contains the processor revision level for the
device. Use this information when requesting support.
3.4
INITIALIZATION AND RESET
This document uses the following terms throughout:
■
External or power-on reset: A reset caused by asserting RES.
■
Internal reset: A reset initiated by the watchdog timer.
■
System reset: Resets the microcontroller (the CPU plus the internal peripherals) as
well as any external peripherals connected to RESOUT. An external reset always causes
a system reset; an internal reset can optionally cause a system reset.
Processor initialization or startup is accomplished by either an external reset or by an
internal reset initiated by the watchdog timer. Resets force the microcontroller to terminate
all execution and local bus activity. No instruction or bus activity occurs as long as the
processor is in reset.
In all resets, the multiplexed pins default to the signal as shown in Table 3-7 on page 3-10
(the signal name without brackets). Pins are latched on the deassertion of RES, and
therefore are not affected by an internal watchdog-timer-generated reset. These latched
pins include the reset configuration pins (pinstraps) shown in Table 3-5 on page 3-7 and
the RESCON register inputs.
After an external or internal reset has completed and an internal processing interval elapses,
the microcontroller begins execution with the instruction at physical location FFFF0h and
the watchdog timer starts counting (reset enables the watchdog timer). RES must be
asserted for at least 1 ms during power-up to allow the internal circuits to stabilize. If the
RES signal is asserted while the watchdog timer is performing a watchdog timer reset, the
external reset takes precedence.
The Am186CC/CH/CU microcontrollers also feature a Reset Out (RESOUT) signal, which
indicates that the microcontroller is being reset (either externally or internally) and can be
used as a system reset to reset any external peripherals connected to RESOUT.
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...