Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

 

 

 

CLOCKS

P89LPC901/902/903

 

 

2. CLOCKS

 

 

Enhanced CPU

The P89LPC901/902/903 uses an enhanced 80C51 CPU which runs at 6 times the speed of standard 80C51 devices. A machine cycle consists of two CPU clock cycles, and most instructions execute in one or two machine cycles.

Clock Definitions

The P89LPC901/902/903 device has several internal clocks as defined below:

•OSCCLK - Input to the DIVM clock divider. OSCCLK is selected from one of the clock sources (see Figure 2-3,Figure 2- 4,Figure 2-5) and can also be optionally divided to a slower frequency (see section "CPU Clock (CCLK) Modification: DIVM Register"). Note: fOSC is defined as the OSCCLK frequency.

•XCLK - Output of the crystal oscillator (P89LPC901)

•CCLK - CPU clock.

•PCLK - Clock for the various peripheral devices and is CCLK/2

CPU Clock (OSCCLK)

The P89LPC901 provides several user-selectable oscillator options. This allows optimization for a range of needs from high precision to lowest possible cost. These options are configured when the FLASH is programmed and include an on-chip watchdog oscillator, an on-chip RC oscillator, an oscillator using an external crystal, or an external clock source. The crystal oscillator can be optimized for low, medium, or high frequency crystals covering a range from 20 kHz to 12 MHz.

The P89LPC902 and P89LPC903 devices allow the user to select between an on-chip watchdog oscillator and an on-chip RC oscillator as the CPU clock source.

Low Speed Oscillator Option - P89LPC901

This option supports an external crystal in the range of 20 kHz to 100 kHz. Ceramic resonators are also supported in this configuration.

Medium Speed Oscillator Option - P89LPC901

This option supports an external crystal in the range of 100 kHz to 4 MHz. Ceramic resonators are also supported in this configuration.

High Speed Oscillator Option - P89LPC901

This option supports an external crystal in the range of 4MHz to 12 MHz. Ceramic resonators are also supported in this configuration. If CCLK is 8MHz or slower, the CLKLP SFR bit (AUXR1.7) can be set to ’1’ to reduce power consumption. On reset, CLKLP is ’0’ allowing highest performance access. This bit can then be set in software if CCLK is running at 8MHz or slower.

2003 Dec 8

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Philips P89LPC903, P89LPC902 Enhanced CPU, Clock Definitions, CPU Clock Oscclk, Low Speed Oscillator Option P89LPC901
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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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