CSP1027 Datasheet, PDF (23/64 Pages) Agere Systems – CSP1027 Voice Band Codec for Cellular Handset and Modem Applications

Data Sheet
December 1999
4 Architectural Information (continued)
VDD
SMODE1
SMODE0
SMODE2
DEV0
(CSP1027)
CSP1027 Voice Band Codec for
Cellular Handset and Modem Applications
DEV1
(DSP1610)
DEV7
(DSP1616)
DATA
CK
ADD
SYN
Figure 24. Multiprocessor Communication and Connections
5-4181 (F).C
4.6.6 Multiprocessor Configuration (SMODE[1:0] = 1X)
The CSP1027 serial I/O supports a multiprocessor mode
that allows multiple devices to be connected together to
provide data transmission between any of the individual
devices. This mode requires no external hardware and
uses a time-division multiplex (TDM) interface with eight
time slots per frame.
Figure 24 shows an example of a multiprocessor system
with multiple DSPs and a CSP1027. The following pins
are connected together to form a four-wire bus:
s DI and DO from the CSP1027s and DSPs form a data
line referred to as DATA.
s IOCK from the CSP1027s and ICK and OCK from the
DSPs form a clock line referred to as CK.
s SADD from the CSP1027s and DSPs form an address
line referred to as ADD.
s SYNC from the CSP1027s and DSPs form a synchro-
nization line referred to as SYN.
Figure 25 on page 25 shows the time-slot allocation tim-
ing used in multiprocessor mode. One frame is defined
as the time between SYN high-to-low transitions. Each
frame is divided into eight time slots of 16 bits each. A
high-to-low transition of SYN defines the beginning of
time slot 0 and also resynchronizes any devices which
are operating on the multiprocessor bus with SYN as an
input. Note that the DSP device which drives the multi-
processor bus during time slot 0 also drives the SYN line.
Each CSP1027 sends data in a time slot determined by
its SMODE0 pin. Each DSP sends data in a time slot or
time slots determined by its tdms register. Only one
device can be assigned a particular time slot, and each
of the eight time slots must be assigned to a device (note
that one device can be assigned more than one time
slot). These requirements must be met by the user's
choice of CSP1027’s SMODE0 connections and the
DSP’s tdms register contents. A CSP1027 is assigned to
time slot 2 if SMODE0 is low or to time slot 5 if SMODE0
is high. This allows up to two CSP1027s to be placed on
a multiprocessor bus.
The DSP input/output format can be configured to either
most significant bit (MSB) first or least significant bit
(LSB) first. The CSP1027 only supports MSB first format;
hence, the DSPs connected on a multiprocessor bus
must be using MSB first data format, configured in the
sioc register, when transferring and receiving data and
control words with the CSP1027.
Lucent Technologies Inc.
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