Comparator and Power Reduction Modes

	Philips Semiconductors	User’s Manual - Preliminary -

	ANALOG COMPARATORS	P89LPC901/902/903

an interrupt if the comparator interrupt is enabled. The user should therefore disable the comparator interrupt prior to disabling the comparator. Additionally, the user should clear the comparator flag, CMFx, after disabling the comparator.

The comparator(s) may remain enabled when Power down or Idle mode is activated, but the comparator(s) are disabled automatically in Total Power down mode.

If the comparator interrupt is enabled (except in Total Power down mode), a change of the comparator output state will generate an interrupt and wake up the processor.

If the comparator output to a pin is enabled, the pin should be configured in the push-pull mode in order to obtain fast switching times while in power down mode. The reason is that with the oscillator stopped, the temporary strong pullup that normally occurs during switching on a quasi-bidirectional port pin does not take place.

The comparator consumes power in Power down and Idle modes, as well as in the normal operating mode. This fact should be taken into account when system power consumption is an issue. To minimize power consumption, the user can disable the comparator via PCONA.5 or put the device in Total Power down mode.

Comparator Configuration Example

The code shown below is an example of initializing the comparator. This comparator is configured to use the CMPREF inputs. The comparator output drives the CMP pin and generates an interrupt when the comparator output changes.

CMPINIT:
MOV	PT0AD,#030h	; Disable digital INPUTS on pins that are used
		; for analog functions: CIN, CMPREF.
ANL	P0M2,#0CFh	; Disable digital OUTPUTS on pins that are used
ORL	P0M1,#030h	; for analog functions: CIN, CMPREF.
MOV	CMP1,#024h	; Turn on comparator and set up for:
		; - Negative input from CMPREF pin.
		; - Output to CMP pin enabled.
CALL	delay10us	; The comparator has to start up for at
		; least 10 microseconds before use.
ANL	CMP1,#0FEh	; Clear comparator interrupt flag.
SETB	EC	; Enable the comparator interrupt. The
		; priority is left at the current value.
SETB	EA	; Enable the interrupt system (if needed).
RET		; Return to caller.

The interrupt routine used for the comparator must clear the interrupt flag (CMF1 in this case) before returning.

2003 Dec 8

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.

Philips P89LPC901 Comparator and Power Reduction Modes, Comparator Configuration Example

Models: P89LPC903 P89LPC902 P89LPC901

P89LPC901/902/903