14-30
DSP56305 User’s Manual
MOTOROLA
CYCLIC CODE CO-PROCESSOR
Configuration Examples
14.7.3
GSM Fire Decode
The Fire decode processes the data block plus the CRC sequence calculated by the Fire
encode. Fire decode is capable of correcting any burst of errors up to 12 bits in length.
The algorithm makes use of the generator polynomial G(D) as well as a multiplication
polynomial M(D) given by:
The Fire decode flow is composed of the following steps:
1. Invert the received 40 CRC bits. This is done by the core and is based on the
assumption that the CRC bits were inverted prior to transmission.
2. Set Input Counter = 224, and Run Counter = 224 (in CCNT)
3. Set INE0 and INE1 in CSFTB
4. Set OPM[1:0], HOZD, and clear LRC (in CCSR)
5. Insert 224 bits (184 data bits + 40 inverted CRC) - CCOP input phase.
6. If D1 to D40 (the 40 MSB’s of the concatenated CFSR) equal zero, then the data
block is error free. Terminate processing.
7. Otherwise, an error is present, enter run phase and:
a. Shift CFSR (input data disabled) until D1 - D28 equals zero.
The start location of the burst error is the number of shifts done until D1– D28
equal zero. This is determined by 224 minus the Run Counter value after a
zero is detected in bits D1–D28.
b. If the start location lies in the data sequence (bits 0 – 183), the errors are
corrected by XORing the data bits with the contents of D40 – D29.
The 12-bit correcting sequence is determined by reading CFSRA and
extracting the bits D40 – D29 (bits 19:8 in CFSRA).
c. If the number of shifts exceeds 224 without D1 – D28 = 0 detection, data is
uncorrectable. This is determined by process termination (PCDN set) while
Run Counter equals zero (224 shifts done).
The CFSR configuration for GSM Fire decode is shown in Figure 14-11.
M D
( )
D
39
D
33
D
29
D
27
D
16
D
10
D
6
+
+
+
+
+
+
D
4
1
+
+
=
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 ...