LPC2921 datasheet(31/81 Pages) PHILIPS

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LPC2921_2923_2925_0

Preliminary data sheet

Rev. 00.01 — 24 October 2008

31 of 81

NXP Semiconductors

LPC2921/2923/2925

ARM9 microcontroller with CAN and LIN

• Programmable clocks allow versatile rate control.

• Bidirectional data transfer between masters and slaves.

• Multi-master bus (no central master).

• Arbitration between simultaneously transmitting masters without corruption of serial

data on the bus.

• Serial clock synchronization allows devices with different bit rates to communicate via

one serial bus.

• Serial clock synchronization can be used as a handshake mechanism to suspend and

resume serial transfer.

• The I2C-bus can be used for test and diagnostic purposes.

• All I2C-bus controllers support multiple address recognition and a bus monitor mode.

6.13.3.1

Pin description

[1]

Note that the pins are not I2C-bus compliant open-drain pins.

6.14 Modulation and sampling control subsystem

The Modulation and Sampling Control Subsystem (MSCSS) in the LPC2921/2923/2925

includes four Pulse-Width Modulators (PWMs), two 10-bit successive approximation

Analog-to-Digital Converters (ADCs) and two timers.

The key features of the MSCSS are:

• Two 10-bit, 400 ksamples/s, 8-channel ADCs with 3.3 V inputs and various trigger-

start options.

• Four 6-channel PWMs (Pulse-Width Modulators) with capture and trap functionality.

• Two dedicated timers to schedule and synchronize the PWMs and ADCs.

• Quadrature encoder interface.

6.14.1 Functional description

The MSCSS contains Pulse-Width Modulators (PWMs), Analog-to-Digital Converters

(ADCs) and timers.

Figure 5 provides an overview of the MSCSS. An AHB-to-APB bus bridge takes care of

communication with the AHB system bus. Two internal timers are dedicated to this

subsystem. MSCSS timer 0 can be used to generate start pulses for the ADCs and the

first PWM. The second timer (MSCSS timer 1) is used to generate ‘carrier’ signals for the

PWMs. These carrier patterns can be used, for example, in applications requiring current

control. Several other trigger possibilities are provided for the ADCs (external, cascaded

or following a PWM). The capture inputs of both timers can also be used to capture the

start pulse of the ADCs.

Table 19.

I2C-bus pins[1]

Symbol

Pin name

Direction

Description

I2C SCL0/1

SCL0/1

I/O

I2C clock input/output

I2C SDA0/1

SDA0/1

I/O

I2C data input/output

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