Datasheet

© 2006 Microchip Technology Inc. DS70117F-page 125
dsPIC30F6011/6012/6013/6014
18.0 DATA CONVERTER
INTERFACE (DCI) MODULE
18.1 Module Introduction
The dsPIC30F Data Converter Interface (DCI) module
allows simple interfacing of devices, such as audio
coder/decoders (Codecs), A/D converters and D/A
converters. The following interfaces are supported:
• Framed Synchronous Serial Transfer (Single or
Multi-Channel)
• Inter-IC Sound (I
2
S) Interface
• AC-Link Compliant mode
The DCI module provides the following general
features:
• Programmable word size up to 16 bits
• Support for up to 16 time slots, for a maximum
frame size of 256 bits
• Data buffering for up to 4 samples without CPU
overhead
18.2 Module I/O Pins
There are four I/O pins associated with the module.
When enabled, the module controls the data direction
of each of the four pins.
18.2.1 CSCK PIN
The CSCK pin provides the serial clock for the DCI
module. The CSCK pin may be configured as an input
or output using the CSCKD control bit in the DCICON1
SFR. When configured as an output, the serial clock is
provided by the dsPIC30F. When configured as an
input, the serial clock must be provided by an external
device.
18.2.2 CSDO PIN
The serial data output (CSDO) pin is configured as an
output only pin when the module is enabled. The
CSDO pin drives the serial bus whenever data is to be
transmitted. The CSDO pin is tri-stated or driven to ‘0’
during CSCK periods when data is not transmitted,
depending on the state of the CSDOM control bit. This
allows other devices to place data on the serial bus
during transmission periods not used by the DCI
module.
18.2.3 CSDI PIN
The serial data input (CSDI) pin is configured as an
input only pin when the module is enabled.
18.2.3.1 COFS PIN
The Codec frame synchronization (COFS) pin is used
to synchronize data transfers that occur on the CSDO
and CSDI pins. The COFS pin may be configured as an
input or an output. The data direction for the COFS pin
is determined by the COFSD control bit in the
DCICON1 register.
The DCI module accesses the shadow registers while
the CPU is in the process of accessing the memory
mapped buffer registers.
18.2.4 BUFFER DATA ALIGNMENT
Data values are always stored left justified in the buff-
ers since most Codec data is represented as a signed
2’s complement fractional number. If the received word
length is less than 16 bits, the unused LSbs in the
receive buffer registers are set to ‘0’ by the module. If
the transmitted word length is less than 16 bits, the
unused LSbs in the transmit buffer register are ignored
by the module. The word length setup is described in
subsequent sections of this document.
18.2.5 TRANSMIT/RECEIVE SHIFT
REGISTER
The DCI module has a 16-bit shift register for shifting
serial data in and out of the module. Data is shifted in/
out of the shift register MSb first, since audio PCM data
is transmitted in signed 2’s complement format.
18.2.6 DCI BUFFER CONTROL
The DCI module contains a buffer control unit for trans-
ferring data between the shadow buffer memory and
the serial shift register. The buffer control unit is a sim-
ple 2-bit address counter that points to word locations
in the shadow buffer memory. For the receive memory
space (high address portion of DCI buffer memory), the
address counter is concatenated with a ‘0’ in the MSb
location to form a 3-bit address. For the transmit mem-
ory space (high portion of DCI buffer memory), the
address counter is concatenated with a ‘1’ in the MSb
location.
Note: This data sheet summarizes features of this group
of dsPIC30F devices and is not intended to be a complete
reference source. For more information on the CPU,
peripherals, register descriptions and general device
functionality, refer to the “dsPIC30F Family Reference
Manual” (DS70046).
Note: The DCI buffer control unit always
accesses the same relative location in the
transmit and receive buffers, so only one
address counter is provided.