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UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
1201 of 1441
NXP Semiconductors
UM10503
Chapter 44: LPC43xx/LPC43Sxx I2S interface
•
Versatile clocking includes independent transmit and receive fractional rate
generators, and an ability to use a single clock input or output for a 4-wire mode.
•
The sampling frequency (fs) can range (in practice) from 16 to 192 kHz (16, 22.05, 32,
44.1, 48, 96, or 192 kHz) for audio applications.
•
Separate Master Clock outputs for both transmit and receive channels support a clock
up to 512 times the I
2
S sampling frequency.
•
Word Select period in master mode is configurable (separately for I
2
S input and I
2
S
output).
•
Two 8 word (32 byte) 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.
44.4 General description
The I2S performs serial data out via the transmit channel and serial data in via the receive
channel. These support the Inter IC Audio format for 8-bit, 16-bit and 32-bit 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 words.
The I2S receive and transmit stage can operate independently in either slave or master
mode. In master mode, the I2S module supplies the SCK and WS signals. In slave mode,
the SCK and WS signals are provided by the external master.
•
In master mode, word select is generated internally with a 9-bit counter. The ratio of
the SCK and WS signals can be programmed in the control register.
•
In slave mode, word select is input from the relevant bus pin.
•
When an I2S bus is active, the word select, receive clock and transmit clock signals
are sent continuously by the bus master, while data is sent continuously by the
transmitter.
•
Disabling the I2S can be done with the stop or mute control bits separately for the
transmit and receive.
•
The stop bit will disable accesses by the transmit channel or the receive channel to
the FIFOs and will place the transmit channel in mute mode.
•
The mute control bit will place the transmit channel in mute mode. In mute mode, the
transmit channel FIFO operates normally, but the output is discarded and replaced by
zeroes. This bit does not affect the receive channel, data reception can occur
normally.
44.4.1 I2S connection schemes
I2S1 is automatically a slave to I2S0 if no external pins are selected for the I2S1 clock and
data lines.