UM10237_2 © NXP B.V. 2008. All rights reserved.
User manual Rev. 02 — 19 December 2008 611 of 792
1. Basic configuration
The I2S interface is configured using the following registers:
1. Power: In the PCONP register (Tab le 4– 63), set bit PCI2S.
Remark: On reset, the I2S interface is disabled (PCI2S = 0).
2. Clock: In PCLK_SEL1 select PCLK_I2S, see Table 4–57.
3. Pins: Select I2S pins and their modes in PINSEL0 to PINSEL4 and PINMODE0 to
PINMODE4 (see Section 9–5).
4. Interrupts are enabled in the VIC using the VICIntEnable register (Section 7–3.4).
2. Features
The I2S bus provides a standard communication interface for digital audio applications.
The I2S bus specification defines a 3-wire serial bus, having 1 data, 1 clock, and one word
select signal. The basic I2S connection has one master, which is always the master, and
one slave. The I2S interface on the LPC2400 provides a separate transmit and receive
channel, each of which can operate as either a master or a slave.
The I2S output can operate in both master and slave mode, independent of the I2S
input.
Capable of handling 8, 16, and 32 bit word sizes.
Mono and stereo audio data supported.
The sampling frequency can range (in practice) from 16 - 96 kHz. (16, 22.05, 32, 44.1,
48, 96 kHz) for audio applications.
Word Select period in master mode is configurable (separately for I2S input and I2S
output).
Two 8 word FIFO data buffers are provided, one for transmit and one for receive.
Generates interrupt requests when buffer levels cross a programmable boundary.
Two DMA requests, controlled by programmable buffer levels. These are connected
to the General Purpose DMA block.
Controls include reset, stop and mute options separately for I2S input and I2S output.
3. Description
The I2S performs serial data out via the transmit channel and serial data in via the receive
channel. These support the NXP Inter IC Audio format for 8, 16 and 32 bits audio data
both for stereo and mono modes. Configuration, data access and control is performed by
a APB register set. Data streams are buffered by FIFOs with a depth of 8 bytes.
The I2S receive and transmit stage can operate independently in either slave or master
mode. Within the I2S module the difference between these modes lies in the word select
(WS) signal which determines the timing of data transmissions. Data words start on the
UM10237
Chapter 23: LPC24XX I2S interface
Rev. 02 — 19 December 2008 User manual