Am186™CC/CH/CU Microcontrollers User’s Manual
7-1
CHAPTER
7
INTERRUPTS
7.1
OVERVIEW
An interrupt is a request to the CPU for service. CPUs receive interrupt requests from a
variety of sources, both internal and external. When the CPU receives a request, it stops
executing the current task, and if the new task is of higher priority, begins executing that
routine. At the end of the routine, the CPU returns to the original task.
Some interrupts can be disabled. These are called
maskable interrupts. Nonmaskable
interrupts cannot be disabled.
The Am186CC/CH/CU microcontrollers feature an interrupt controller, which arranges the
maskable interrupt requests by priority and presents them one at a time to the CPU. In
addition to interrupts managed by the interrupt controller, the microcontroller supports eight
nonmaskable interrupts—an external or internal nonmaskable interrupt (NMI), a trace
interrupt, and software interrupts and exceptions.
The interrupt controller supports the maskable interrupt sources through the use of 15
channels. To make this possible, most interrupt channels support multiple interrupt sources.
These channels are programmable to support the external interrupt pins or various
peripheral devices that can be configured to generate interrupts. The maskable interrupt
sources include 17 external sources plus a number of internal sources.
The Am186CC microcontroller has 19 internal maskable interrupt sources.
The Am186CH HDLC microcontroller has 14 internal maskable interrupt sources.
The Am186CU USB microcontroller has 13 internal maskable interrupt sources.
The following Am186CC microcontroller peripherals can generate internal interrupts:
■
Three on-board timers (two of the timers can operate as pulse width modulators)
■
Two UARTs
■
Four HDLC channels
■
The GCI
■
Four pairs of transmit/receive SmartDMA channels
■
Four general-purpose DMA channels
■
The USB peripheral controller
CC
CH
CU
CC
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...