8-16
DSP56309UM/D MOTOROLA
Serial Communication Interface (SCI)
SCI Programming Model
¥ For asynchronous mode, the output clock is continuous.
¥ For 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.
¥ For synchronous mode, the clock is gated.
¥ For synchronous mode, the transmitter and receiver are synchronous with each
other.
8.3.3.1
SCCR Clock Divider (CD[11:0]) Bits 11Ð0
The CD[11:0] bits specify the divide ratio of the prescale divider in the SCI clock
generator. A divide ratio from 1 to 4096 (CD[11:0] = $000 to $FFF) can be selected. Either
a hardware RESET signal or a software RESET instruction clears CD11ÐCD0.
8.3.3.2
SCCR Clock Out Divider (COD) Bit 12
The clock output divider is controlled by COD and SCI mode. If SCI mode is
synchronous, the output divider is fixed at divide by 2.
If SCI mode is asynchronous, then one of the following conditions occurs:
¥ If COD is cleared and SCLK is an output (i.e., TCM and RCM are both cleared),
the SCI clock is divided by 16 before being output to the SCLK signal. Thus, the
SCLK output is a 1
´
clock.
¥ If COD is set and SCLK is an output, the SCI clock is fed directly out to the SCLK
signal. Thus, the SCLK output is a 16
´
baud clock.
Either a hardware RESET signal or a software RESET instruction clears COD.
Figure 8-5
16 x Serial Clock
RX, TX Data
(SSFTD = 0)
Idle Line
Start
Select 8-or 9-bit Words
x1 Clock
x16 Clock
(SCKP = 0)
1
0
2
3
4
5
6
7
8
AA0692
Stop
Start
Summary of Contents for DSP56309
Page 25: ...xxii DSP56309UM D MOTOROLA Figure D 25 Port E Registers PCRE PRRE PDRE D 39 ...
Page 30: ...MOTOROLA DSP56309UM D 1 1 SECTION 1 DSP56309 OVERVIEW ...
Page 47: ...1 18 DSP56309UM D MOTOROLA DSP56309 Overview DSP56309 Architecture Overview ...
Page 48: ...MOTOROLA DSP56309UM D 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Page 85: ...2 38 DSP56309UM D MOTOROLA Signal Connection Descriptions OnCE JTAG Interface ...
Page 86: ...MOTOROLA DSP56309UM D 3 1 SECTION 3 MEMORY CONFIGURATION ...
Page 104: ...MOTOROLA DSP56309UM D 4 1 SECTION 4 CORE CONFIGURATION ...
Page 124: ...MOTOROLA DSP56309UM D 5 1 SECTION 5 GENERAL PURPOSE I O ...
Page 125: ...5 2 DSP56309UM D MOTOROLA General Purpose I O 5 1 INTRODUCTION 5 3 5 2 PROGRAMMING MODEL 5 3 ...
Page 128: ...MOTOROLA DSP56309UM D 6 1 SECTION 6 HOST INTERFACE HI08 ...
Page 166: ...MOTOROLA DSP56309UM D 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Page 212: ...MOTOROLA DSP56309UM D 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Page 241: ...8 30 DSP56309UM D MOTOROLA Serial Communication Interface SCI GPIO Signals and Registers ...
Page 242: ...MOTOROLA DSP56309UM D 9 1 SECTION 9 TRIPLE TIMER MODULE ...
Page 269: ...9 28 DSP56309UM D MOTOROLA Triple Timer Module Timer Operational Modes ...
Page 270: ...MOTOROLA DSP56309UM D 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Page 302: ...MOTOROLA DSP56309UM D 11 1 SECTION 11 JTAG PORT ...
Page 369: ...C 22 DSP56309UM D MOTOROLA DSP56309 BSDL Listing ...
Page 370: ...MOTOROLA DSP56309UM D D 1 APPENDIX D PROGRAMMING REFERENCE ...
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