Serial Communication Interface (SCI)
SCI Programming Model
MOTOROLA
DSP56305 User’s Manual
8-15
Register is written. TDRE is set by the hardware, software, SCI individual, and stop
reset.
In the Synchronous mode, when using the internal SCI clock, there is a delay of up to 5.5
serial clock cycles between the time that STX is written until TDRE is set, indicating the
data has been transferred from the STX to the Transmit Shift Register. There is a 2 to 4
serial clock cycle delay between writing STX and loading the Transmit Shift Register; in
addition, TDRE is set in the middle of transmitting the second bit. If the clock stops
when using an external serial transmit clock, the SCI transmitter stops. TDRE is not set
until the middle of the second bit transmitted after the external clock starts. Gating the
external clock off after the first bit has been transmitted delays TDRE indefinitely.
In the Asynchronous mode, the TDRE flag is not set immediately after a word is
transferred from the STX or STXA to the Transmit Shift Register nor when the word first
begins to be shifted out. TDRE is set 2 cycles of the 16
×
clock after the start bit—that is, 2
16
×
clock cycles into the transmission time of the first data bit.
8.3.2.3
Receive Data Register Full (RDRF) SSR Bit 2
The RDRF bit is set when a valid character is transferred to the SCI Receive Data Register
from the SCI Receive Shift Register (regardless of the error bits condition). RDRF is
cleared when the SCI Receive Data Register is read or by the hardware, software, SCI
individual, and stop resets.
8.3.2.4
Idle Line Flag (IDLE) SSR Bit 3
IDLE is set when ten (or eleven) consecutive 1s are received. IDLE is cleared by a
start-bit detection. The IDLE status bit represents the status of the receive line. The
transition of IDLE from 0 to 1 can cause an IDLE interrupt (ILIE). IDLE is cleared by the
hardware, software, SCI individual, and Stop resets.
8.3.2.5
Overrun Error Flag (OR) SSR Bit 4
The OR flag bit is set when a byte is ready to be transferred from the Receive Shift
Register to the Receive Data Register (SRX) that is already full (RDRF = 1). The Receive
Shift Register data is not transferred to the SRX. The OR flag indicates that character(s) in
the received data stream may have been lost. The only valid data is located in the SRX.
OR is cleared when the SCI status Register (SSR) is read, followed by a read of SRX. The
OR bit clears the FE and PE bits—that is, overrun error has higher priority than FE or PE.
OR is cleared by the hardware, software, SCI individual, and stop resets.
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 ...