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
Содержание DSP56309
Страница 25: ...xxii DSP56309UM D MOTOROLA Figure D 25 Port E Registers PCRE PRRE PDRE D 39 ...
Страница 30: ...MOTOROLA DSP56309UM D 1 1 SECTION 1 DSP56309 OVERVIEW ...
Страница 47: ...1 18 DSP56309UM D MOTOROLA DSP56309 Overview DSP56309 Architecture Overview ...
Страница 48: ...MOTOROLA DSP56309UM D 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Страница 85: ...2 38 DSP56309UM D MOTOROLA Signal Connection Descriptions OnCE JTAG Interface ...
Страница 86: ...MOTOROLA DSP56309UM D 3 1 SECTION 3 MEMORY CONFIGURATION ...
Страница 104: ...MOTOROLA DSP56309UM D 4 1 SECTION 4 CORE CONFIGURATION ...
Страница 124: ...MOTOROLA DSP56309UM D 5 1 SECTION 5 GENERAL PURPOSE I O ...
Страница 125: ...5 2 DSP56309UM D MOTOROLA General Purpose I O 5 1 INTRODUCTION 5 3 5 2 PROGRAMMING MODEL 5 3 ...
Страница 128: ...MOTOROLA DSP56309UM D 6 1 SECTION 6 HOST INTERFACE HI08 ...
Страница 166: ...MOTOROLA DSP56309UM D 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Страница 212: ...MOTOROLA DSP56309UM D 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Страница 241: ...8 30 DSP56309UM D MOTOROLA Serial Communication Interface SCI GPIO Signals and Registers ...
Страница 242: ...MOTOROLA DSP56309UM D 9 1 SECTION 9 TRIPLE TIMER MODULE ...
Страница 269: ...9 28 DSP56309UM D MOTOROLA Triple Timer Module Timer Operational Modes ...
Страница 270: ...MOTOROLA DSP56309UM D 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Страница 302: ...MOTOROLA DSP56309UM D 11 1 SECTION 11 JTAG PORT ...
Страница 369: ...C 22 DSP56309UM D MOTOROLA DSP56309 BSDL Listing ...
Страница 370: ...MOTOROLA DSP56309UM D D 1 APPENDIX D PROGRAMMING REFERENCE ...
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