445
CHAPTER 22 SERIAL I/O
22.3
Serial I/O Prescaler (CDCR)
The Serial I/O Prescaler provides the shift clock for the Serial I/O.
The operation clock for the Serial I/O is obtained by dividing the machine clock. The
Serial I/O is designed so that a constant baud rate can be obtained for a variety of
machine clocks by the use of the communication prescaler. The CDCR register controls
the machine clock division.
■
Serial I/O Prescaler (CDCR)
Figure 22.3-1 Configuration of the Serial I/O Prescaler (CDCR)
Note:
When the division ratio is changed, allow two cycles for the clock to stabilize before starting
communication.
MD
Machine Clock Divide Mode Select bit
0
The Serial I/O Prescaler is disabled.
1
The Serial I/O Prescaler is enabled.
MD
-
NEG
-
-
-
DIV3
DIV2
DIV1
DIV0
Initial value
0 X 0 X 0 0 0 0
B
Address
00002F
H
bit14
bit15
bit13
bit12
bit11
bit10
bit9
bit8
R/W
R/W
R/W
R/W
R/W
R/W
DIV3 to
DIV0
Machine Clock Division Ratio bits
0000
B
Division ratio: div = 1
0001
B
Division ratio: div = 2
0010
B
Division ratio: div = 3
0011
B
Division ratio: div = 4
0100
B
Division ratio: div = 5
0101
B
Division ratio: div = 6
0110
B
Division ratio: div = 7
0111
B
Division ratio: div = 8
1xxx
B
reserved
R/W :
Readable and
w
ritable
: Initial value
NEG
Negative Clock Operation bit
0
Normal operation
1
The shift clock signal is inverted
X
: Undefined value
-
: Undefined
Содержание MB90390 Series
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Страница 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
Страница 18: ...xiv ...
Страница 132: ...104 CHAPTER 5 CLOCKS ...
Страница 152: ...124 CHAPTER 6 CLOCK MODULATOR ...
Страница 210: ...182 CHAPTER 11 TIME BASE TIMER ...
Страница 218: ...190 CHAPTER 12 WATCHDOG TIMER ...
Страница 264: ...236 CHAPTER 14 16 BIT RELOAD TIMER WITH EVENT COUNT FUNCTION ...
Страница 274: ...246 CHAPTER 15 WATCH TIMER ...
Страница 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
Страница 338: ...310 CHAPTER 18 8 10 BIT A D CONVERTER ...
Страница 364: ...336 CHAPTER 19 UART0 UART1 ...
Страница 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
Страница 432: ...404 CHAPTER 20 UART2 UART3 ...
Страница 482: ...454 CHAPTER 22 SERIAL I O ...
Страница 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
Страница 582: ...554 CHAPTER 27 ROM MIRRORING MODULE ...
Страница 632: ...604 CHAPTER 29 EXAMPLES OF SERIAL PROGRAMMING CONNECTION ...
Страница 722: ...694 APPENDIX ...
Страница 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
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