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Philips Semiconductors Product specification<br />

8-bit microcontroller with on-chip CAN P8xC592<br />

14 INTERRUPT SYSTEM<br />

External events and the real-time-driven on-chip<br />

peripherals require service by the CPU asynchronous to<br />

the execution of any particular section of code. To tie the<br />

asynchronous activities of these functions to normal<br />

program execution a multiple-source, two-priority-level,<br />

nested interrupt system is provided. Interrupt response<br />

latency is from 2.25 μs to7.5μs when using a 16 MHz<br />

crystal. The latency time strongly depends on the<br />

sequence of instructions executed directly after an<br />

interrupt request. During a CAN-DMA transfer the interrupt<br />

system is disabled (see Section 13.5.17). The P8xC592<br />

acknowledges interrupt requests from fifteen sources as<br />

follows:<br />

• INT0 and INT1: externally via pins 27 and 28<br />

respectively<br />

• Timer 0 and Timer 1: from the two internal counters<br />

– If the capture function remains unused and the<br />

Capture Register contents are ‘don't care’ then the<br />

corresponding input pins ‘CTnI’, with ‘n = 0 ... 3’, may<br />

be used as positive and/or negative edge triggered<br />

external interrupts INT2 to INT5. But note that they<br />

can not terminate the Idle mode because the Timer 2<br />

is switched off then<br />

• Timer T2, 8 separate interrupts:<br />

– 4 capture interrupts<br />

– 3 compare interrupts<br />

– an overflow interrupt<br />

• ADC end-of-conversion interrupt<br />

• CAN-controller interrupt<br />

• UART serial I/O port interrupt.<br />

Each interrupt vectors to a separate location in Program<br />

Memory for its service program. Each source can be<br />

individually enabled or disabled by a corresponding bit in<br />

the IEN0 or IEN1 register, moreover each interrupt may be<br />

programmed to a HIGH or LOW priority level using a<br />

corresponding bit in the IP0 or IP1 register. Also all<br />

enabled sources can be globally disabled or enabled. Both<br />

external interrupts can be programmed to be<br />

level-activated or transition-activated, and an active LOW<br />

level allows ‘wire-ORing’ of several interrupt sources to the<br />

input pin.<br />

1996 Jun 27 63

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