Serial Communication Interface (SCI)
SCI Programming Model
MOTOROLA
DSP56305 User’s Manual
8-17
8.3.3
SCI Clock Control Register (SCCR)
The SCCR is a sixteen bit read/write register that used to select clock modes and baud
rates for the transmitter and receiver sections of the SCI interface. The control bits are
described in the following paragraphs. The SCCR is cleared by hardware reset. The basic
features of the clock generator (see Figure 8-6 and Figure 8-7) are:
• The SCI logic always uses a 16
×
internal clock in the Asynchronous modes and a
2
×
internal clock in the Synchronous mode. The maximum internal clock
available to the SCI peripheral block is the oscillator frequency divided by 4. With
an 80 MHz DSP56305 processor, this gives a maximum data rate of 1.25 Mbps for
asynchronous data and 10.0 Mbps for synchronous data. These maximum rates
are the same for internally or externally supplied clocks.
• The 16
×
clock is necessary for the Asynchronous modes to synchronize the SCI to
the incoming data (see Figure 8-6).
• In the Asynchronous modes, the user must provide a 16
×
clock if the user wishes
to use an external baud rate generator (i.e., SCLK input).
• In the Asynchronous modes, the user can select either 1
×
or 16
×
for the output
clock when using internal TX and RX clocks (TCM = 0 and RCM = 0).
• If SCKP = 0, the data transmitted on the TXD signal changes on the negative edge
of the 1
×
serial clock and is stable on the positive edge. If SCKP = 1, the data
changes on the positive edge and is stable on the negative edge.
• If SCKP = 0, the data received on the RXD signal is sampled on the positive edge
or if SCKP = 1, on the negative edge of the 1
×
serial clock.
• In the Asynchronous modes, the output clock is continuous.
• In the Synchronous mode, a 1
×
clock is used for the output or input baud rate.
The maximum 1
×
clock is the crystal frequency divided by 8.
• In the Synchronous mode, the clock is gated.
• In the Synchronous mode, the transmitter and receiver are synchronous with each
other.
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 ...