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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

SERIAL COMMUNICATION INTERFACE (SCI)

Table 6-4 (a) Synchronous SCI Bit Rates for a 32.768-MHz Crystal

Baud Rate

 

Divider Bits

Baud Rate

SCP Bit

Error,

(BPS)

(CD0–CD11)

 

Percent

 

 

 

 

 

 

 

 

 

 

 

4.096M

0

$000

0

 

 

 

 

128K

0

$01F

0

 

 

 

 

64K

0

$03F

0

 

 

 

 

56K

0

$048

-0.195

 

 

 

 

32K

0

$07F

0

 

 

 

 

16K

0

$0FF

0

 

 

 

 

8000

0

$1FF

0

 

 

 

 

4000

0

$3FF

0

 

 

 

 

2000

0

$7FF

0

 

 

 

 

1000

0

$FFF

0

 

 

 

 

BPS= f0 ÷ (8 × (7(SCP) + 1) × (CD + 1)); f0=32.768 MHz

SCP=0 or 1

CD=0 to $FFF

Table 6-4 (b) Frequencies for Exact Synchronous SCI Bit Rates

Bit Rate

SCP Bit

Divider Bits

Crystal

(BPS)

(CD0–CD11)

Frequency

 

 

 

 

 

 

 

 

 

2.048M

0

$001

32.768 MHz

 

 

 

 

1.544M

0

$002

37.056 MHz

 

 

 

 

1.536M

0

$002

36.864 MHz

 

 

 

 

f0=BPS × 8 × (7(SCP) + 1) × (CD + 1) SCP=0 or 1

CD=0 to $FFF

6.3.5SCI Exceptions

The SCI can cause five different exceptions in the DSP (see Figure 6-53). These exceptions are as follows:

1.SCI Receive Data – caused by receive data register full with no receive error conditions existing. This error-free interrupt may use a fast interrupt service

MOTOROLA PORT C 6 - 37

For More Information On This Product, Go to: www.freescale.com

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

SERIAL COMMUNICATION INTERFACE (SCI)

EXCEPTION

PROGRAM MEMORY SPACE

 

STARTING

 

 

ADDRESS

 

 

 

 

EXCEPTION SOURCE

 

$0000

HARDWARE RESET

TWO WORDS PER VECTOR EXTERNAL INTERRUPTS

$0002

STACK ERROR

 

 

$0004

TRACE

 

INTERNAL

 

INTERRUPTS

 

 

 

$0006 SWI (SOFTWARE INTERRUPT)

$0008 IRQA EXTERNAL HARDWARE INTERRUPT

$000A IRQB EXTERNAL HARDWARE INTERRUPT $000C SSI RECEIVE DATA

EXTERNAL

INTERRUPTS

$000E

SSI RECEIVE DATA WITH EXCEPTION STATUS

 

SYNCHRONOUS

 

SERIAL

 

 

 

$0010

SSI TRANSMIT DATA

 

INTERFACE

 

 

 

 

$0012

SSI TRANSMIT DATA WITH EXCEPTION STATUS

 

 

$0014

SCI RECEIVE DATA

 

INTERNAL

 

INTERRUPTS

 

 

 

$0016

SCI RECEIVE DATA WITH EXCEPTION STATUS

SERIAL

 

 

 

 

$0018

SCI TRANSMIT DATA

COMMUNICATIONS

 

INTERFACE

 

 

 

 

$001A

SCI IDLE LINE

 

 

$001C

SCI TIMER

 

 

$001E

RESERVED

 

 

$0020

HOST RECEIVE DATA

 

 

$0022

HOST TRANSMIT DATA

 

 

$0024

HOST COMMAND (DEFAULT)

 

 

$0026

AVAILABLE FOR HOST COMMAND

 

 

$0028

AVAILABLE FOR HOST COMMAND

 

 

 

 

 

 

 

 

 

HOST

INTERNAL

$003A

AVAILABLE FOR HOST COMMAND

INTERFACE

INTERRUPTS

 

 

$003C

TIMER

 

 

$003E

ILLEGAL INSTRUCTION

 

 

$0040

AVAILABLE FOR HOST COMMAND

 

 

 

 

 

 

 

 

 

 

 

$007E

AVAILABLE FOR HOST COMMAND

 

 

Figure 6-16 SCI Exception Vector Locations

6 - 38 PORT C MOTOROLA

For More Information On This Product, Go to: www.freescale.com

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