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DSP56305 User’s Manual
MOTOROLA
Enhanced Synchronous Serial Interface (ESSI)
Operating Modes
Time slots are contiguous – with one exception, the last bit time in time slot K is always
immediately followed by the first bit time in time slot K+1. The exception involves the
last time slot in the frame, in conjunction with an external frame sync. If an internal frame
sync is used, the last time slot in the frame will be contiguous with the first time slot in
the next frame. The same situation is possible, but not required, if an external frame sync
is used. In summary, it is possible for an ESSI receive or transmit channel to transfer a
new data bit during every bit time in the frame.
Each ESSI in the network is assigned zero, one, or more receive time slots, and zero, one,
or more transmit time slots. The time slot assignment scheme used is dependent on the
network topology and software multiprocessing algorithm which is used. The receive
and transmit time slots of a given ESSI may be assigned independently of each other if
its receive and transmit pins are on different network nodes, and the multiprocessing
algorithm does not cause them to be interdependent.
An ESSI must receive or transmit only during its assigned receive or transmit time slots,
respectively. For the case in which transmitters from more than one ESSI are connected
to a given network node, this will prevent network collisions. The core code must also
take into account the inherent delays which occur in the ESSI due to double buffering
and serial/parallel conversion. Data written to the transmit register(s) in time slot K will
be shifted out of the ESSI in time slot K+1; data read from the receive register in time slot
K was shifted into the ESSI in time slot K-1. For the purposes of this discussion, any
reference to a “time slot” is from the core point of view. In other words, this is the time
slot in which the appropriate ESSI data register is read or written, as opposed to when
the serial data is actually transferred.
Time slot mask registers may be used to constrain an ESSI to transferring data only
during its assigned time slots. These registers are used to disable the receiver or
transmitter(s), along with the associated status flags, during all but the assigned time
slots. The result is that actions triggered by an ESSI's status flags or interrupts will only
occur during that ESSI's designated receive or transmit time slots. Masking out
unneeded time slots saves core MIPS because the ISRs are only called during the
assigned time slots. Time slot assignment may be predesignated or changed dynamically
(mask register changes take effect in the following frame).
If an ESSI needs to receive during more than one time slot per frame, or transmit during
more than one time slot per frame, then a system must be employed for tracking the
assigned slots within a given frame. Various solutions are possible, such as multiple
DMA channels, software counters, or input/output buffers with a known data
interleaving scheme.
Details on programming the ESSI in network mode are given in subsequent sections.
Summary of Contents for DSP56305
Page 34: ...xxxii DSP56305 User s Manual MOTOROLA ...
Page 40: ...xxxvi DSP56305 User s Manual MOTOROLA ...
Page 41: ...MOTOROLA DSP56305 User s Manual 1 1 SECTION 1 DSP56305 OVERVIEW ...
Page 58: ...1 18 DSP56305 User s Manual MOTOROLA DSP56305 Overview DSP56305 Architecture Overview ...
Page 59: ...MOTOROLA DSP56305 User s Manual 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Page 98: ...2 40 DSP56305 User s Manual MOTOROLA Signal Connection Descriptions JTAG OnCE Interface ...
Page 99: ...MOTOROLA DSP56305 User s Manual 3 1 SECTION 3 MEMORY CONFIGURATION ...
Page 119: ...MOTOROLA DSP56305 User s Manual 4 1 SECTION 4 CORE CONFIGURATION ...
Page 144: ...4 26 DSP56305 User s Manual MOTOROLA Core Configuration JTAG Boundary Scan Register BSR ...
Page 145: ...MOTOROLA DSP56305 User s Manual 5 1 SECTION 5 GENERAL PURPOSE I O ...
Page 149: ...HOST INTERFACE HI32 MOTOROLA DSP56305 User s Manual 6 1 SECTION 6 HOST INTERFACE HI32 ...
Page 150: ...6 2 DSP56305 User s Manual MOTOROLA HOST INTERFACE HI32 ...
Page 259: ...MOTOROLA DSP56305 User s Manual 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Page 315: ...MOTOROLA DSP56305 User s Manual 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Page 347: ...MOTOROLA DSP56305 User s Manual 9 1 SECTION 9 TIMER EVENT COUNTER ...
Page 376: ...9 30 DSP56305 User s Manual MOTOROLA Timer Event Counter Timer Modes of Operation ...
Page 377: ...MOTOROLA DSP56305 User s Manual 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Page 411: ...MOTOROLA DSP56305 User s Manual 11 1 SECTION 11 JTAG PORT ...
Page 430: ...11 20 DSP56305 User s Manual MOTOROLA JTAG Port DSP56305 Boundary Scan Register ...
Page 431: ...Filter Co Processor MOTOROLA DSP56305 User s Manual 12 1 SECTION 12 FILTER CO PROCESSOR ...
Page 471: ...VITERBI CO PROCESSOR MOTOROLA DSP56305 User s Manual 13 1 SECTION 13 VITERBI CO PROCESSOR ...
Page 522: ...13 52 DSP56305 User s Manual MOTOROLA VITERBI CO PROCESSOR References ...
Page 554: ...14 32 DSP56305 User s Manual MOTOROLA CYCLIC CODE CO PROCESSOR Configuration Examples ...
Page 555: ...MOTOROLA DSP56305 User s Manual A 1 APPENDIX A BOOTSTRAP CODE ...
Page 568: ...A 14 DSP56305 User s Manual MOTOROLA Bootstrap Code ...
Page 569: ...Equates MOTOROLA DSP56305 User s Manual B 1 APPENDIX B EQUATES ...
Page 589: ...MOTOROLA DSP56305 User s Manual C 1 APPENDIX C JTAG BSDL ...
Page 590: ...C 2 DSP56305 User s Manual MOTOROLA JTAG BSDL ...
Page 600: ...C 12 DSP56305 User s Manual MOTOROLA JTAG BSDL ...
Page 601: ...MOTOROLA DSP56305 User s Manual D 1 APPENDIX D PROGRAMMING REFERENCE ...
Page 602: ...D 2 DSP56305 User s Manual MOTOROLA PROGRAMMING REFERENCE ...
Page 661: ...Y MOTOROLA DSP56305 User s Manual Index 11 ...
Page 662: ...Y Index 12 DSP56305 User s Manual MOTOROLA ...