Interrupts
Am186™CC/CH/CU Microcontrollers User’s Manual
7-11
7.5.4
Interrupt Priority
Table 7-3 on page 7-12 shows the predefined types and overall priority structure for the
Am186CC/CH/CU microcontrollers. The Overall Priority column shows the priority for the
interrupts at power-on reset and at watchdog timer reset. Interrupt sources that constitute
one request source share the same overall priority level with respect to other interrupt
sources but are prioritized among themselves. This priority is indicated by letters following
the priority number, with A having the highest priority, then B, etc.
Nonmaskable interrupts (types 0h–7h) are always higher priority than maskable interrupts.
Maskable interrupts have a programmable priority, set in the Channel Control (CHxCON)
registers, which overrides the overall priority.
7.5.4.1
Nonmaskable Interrupt and Software Interrupt Priority
The nonmaskable interrupts and software interrupts from 00h to 07h always take priority
over the maskable hardware interrupts. Within the nonmaskable and software interrupts,
the trace interrupt has the highest priority, followed by the NMI/watchdog-timer interrupt,
followed by the remaining software exceptions.
After the trace interrupt and the NMI/watchdog-timer interrupt, the remaining software
exceptions are mutually exclusive and can only occur one at a time, so there is no further
priority breakdown.
7.5.4.2
Maskable Hardware Interrupt Priority
Beginning with interrupt type 08h (the timer 0 interrupt), the maskable hardware interrupts
have both an overall priority and a programmable priority (see Table 7-3). The programmable
priority is the primary priority for maskable hardware interrupts and is set with the PR bit in
the CGxCON registers. The overall priority is the secondary priority for maskable hardware
interrupts.
Each of the maskable hardware interrupts has a programmable priority from zero to seven,
with zero being the highest priority. Because all maskable interrupts are set to a
programmable priority of seven on reset, the overall priority of the interrupts determines
the priority in which each interrupt is granted by the interrupt controller until programmable
priorities are changed by reconfiguring the CHxCON registers.
For example, if the INT6–INT0 interrupts are all changed to programmable priority six and
no other programmable priorities are changed from the reset value of seven, then the INT6–
INT0 interrupts take precedence over all other maskable interrupts. (Within INT6–INT0, the
hierarchy is as follows: INT0>INT1>INT2>INT3>INT4>INT5>INT6.)
Содержание Am186 CC
Страница 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
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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...