Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

 

 

 

INTERRUPTS

P89LPC901/902/903

 

 

3. INTERRUPTS

 

 

The P89LPC901/902/903 use a four priority level interrupt structure. This allows great flexibility in controlling the handling of the many interrupt sources. The P89LPC901 supports 6 interrupt sources: timers 0 and 1, brownout detect, watchdog/ realtime clock, keyboard, and the comparator. The P89LPC902 supports 6 interrupt sources: timers 0 and 1, brownout detect, watchdog/ realtime clock, keyboard, and comparators 1 and 2. The P89LPC903 supports 9 interrupt sources: timers 0 and 1, serial port Tx, serial port Rx, combined serial port Rx/Tx, brownout detect, watchdog/ realtime clock, keyboard, and comparators 1 and 2.

Each interrupt source can be individually enabled or disabled by setting or clearing a bit in the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a global enable bit, EA, which enables all interrupts.

Each interrupt source can be individually programmed to one of four priority levels by setting or clearing bits in the interrupt priority registers IP0, IP0H, IP1, and IP1H. An interrupt service routine in progress can be interrupted by a higher priority interrupt, but not by another interrupt of the same or lower priority. The highest priority interrupt service cannot be interrupted by any other interrupt source. If two requests of different priority levels are pending at the start of an instruction, the request of higher priority level is serviced.

If requests of the same priority level are pending at the start of an instruction, an internal polling sequence determines which request is serviced. This is called the arbitration ranking. Note that the arbitration ranking is only used to resolve pending requests of the same priority level.

Table summarizes the interrupt sources, flag bits, vector addresses, enable bits, priority bits, arbitration ranking, and whether each interrupt may wake up the CPU from a Power down mode.

Interrupt Priority Structure

There are four SFRs associated with the four interrupt levels: IP0, IP0H, IP1, IP1H. Every interrupt has two bits in IPx and IPxH (x = 0,1) and can therefore be assigned to one of four levels, as shown in Table .

Table 3-1: Interrupt priority level

 

Priority Bits

Interrupt Priority Level

 

 

 

IPxH

 

IPx

 

 

 

 

 

 

0

 

0

Level 0 (lowest priority)

0

 

1

Level 1

 

 

 

 

1

 

0

Level 2

 

 

 

 

1

 

1

Level 3 (highest priority)

 

 

 

 

2003 Dec 8

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Philips P89LPC902, P89LPC901, P89LPC903 user manual Interrupt Priority Structure
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P89LPC903, P89LPC902, P89LPC901 specifications

The Philips P89LPC901, P89LPC902, and P89LPC903 are a series of 8-bit microcontrollers designed for embedded system applications. These models, which belong to the LPC900 series, are notable for their affordability and versatility, making them an attractive choice for both hobbyists and professional developers.

One of the core features of the P89LPC901, P89LPC902, and P89LPC903 microcontrollers is their powerful 8-bit architecture. Operating at clock speeds up to 20 MHz, they deliver efficient performance suited for a range of tasks. Each model includes a comprehensive instruction set that supports various data manipulation and arithmetic functions, enabling extensive programming capabilities.

These microcontrollers come with built-in memory, with configurations that vary among the three models. The P89LPC901 typically features 4 KB of Flash memory and 256 bytes of RAM, while the P89LPC902 and P89LPC903 offer enhanced memory options. This Flash memory allows for reprogrammability, making it easier to update and modify applications as needed.

Another significant characteristic of the LPC900 series is their integrated peripherals. These models are equipped with a variety of I/O ports, allowing for easy interfacing with other devices and components. The P89LPC901 supports up to 32 I/O pins, while the P89LPC902 and P89LPC903 provide additional features such as analog-to-digital converters (ADCs), timers, and serial communication interfaces. This broad range of peripherals empowers developers to design complex applications without needing extra hardware.

Power consumption is also a key consideration for microcontroller applications. The P89LPC901, P89LPC902, and P89LPC903 are designed with low power consumption in mind, making them ideal for battery-operated devices and energy-efficient projects. They can operate in various power modes, allowing for greater flexibility in deployment.

In terms of technology, these microcontrollers utilize advanced CMOS technology, ensuring high reliability and durability. Their design offers a robust solution for numerous applications, including consumer electronics, industrial controls, and automation systems.

In summary, the Philips P89LPC901, P89LPC902, and P89LPC903 microcontrollers present an attractive combination of performance, integrated peripherals, low power consumption, and versatility. Their features cater to a wide array of applications, keeping them relevant in a rapidly evolving technology landscape. For hobbyists and professionals alike, these microcontrollers represent a reliable foundation for embedded system development.
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