Philips Semiconductors

 

 

 

User’s Manual - Preliminary -

CLOCKS

 

 

 

P89LPC901/902/903

 

 

 

 

R T C S 1 :0

 

 

 

 

R T C

 

 

 

C P U

 

 

F O S C 2 :0

 

C lo ck

 

 

O S C

 

C C L K

 

 

C L K

D IV M

C P U

 

 

 

R C O sc illa to r

 

 

 

 

(7.3 728 M H z)

 

 

/2

 

W a tc h d o g

 

 

 

W D T

 

 

 

 

O s c illa to r

 

 

 

 

(400 K H z)

 

 

 

 

 

 

 

P C L K

 

B a u d rate

U AR T

 

T im er 0 & 1

 

G en e rato r

 

 

 

 

 

 

Figure 2-5: Block Diagram of Oscillator Control- P89LPC903

CPU Clock (CCLK) Wakeup Delay

The P89LPC901/902/903 has an internal wakeup timer that delays the clock until it stabilizes depending to the clock source used. If the clock source is any of the three crystal selections (P89LPC901), the delay is 992 OSCCLK cycles plus 60-100µs. If the clock source is either the internal RC oscillator or the Watchdog oscillator, the delay is 224 OSCCLK cycles plus 60-100µs.

CPU Clock (CCLK) Modification: DIVM Register

The OSCCLK frequency can be divided down, by an integer, up to 510 times by configuring a dividing register, DIVM, to provide CCLK. This produces the CCLK frequency using the following formula:

CCLK frequency = fOSC / (2N) Where: fOSC is the frequency of OSCCLK

N is the value of DIVM.

Since N ranges from 0 to 255, the CCLK frequency can be in the range of fOSC to fOSC/510 (for N =0, CCLK = fOSC) .

This feature makes it possible to temporarily run the CPU at a lower rate, reducing power consumption. By dividing the clock, the CPU can retain the ability to respond to events other than those that can cause interrupts (i.e. events that allow exiting the Idle mode) by executing its normal program at a lower rate. This can often result in lower power consumption than in Idle mode. This can allow bypassing the oscillator start-up time in cases where Power down mode would otherwise be used. The value of DIVM may be changed by the program at any time without interrupting code execution.

2003 Dec 8

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Philips P89LPC902, P89LPC901 CPU Clock Cclk Wakeup Delay, CPU Clock Cclk Modification Divm Register, L K, O sc illa to r
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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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