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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

SYNCHRONOUS SERIAL INTERFACE (SSI)

6.4.6SSI Exceptions

The SSI can generate four different exceptions (see Figure 6-53 and Figure 6-54):

1.SSI Receive Data – occurs when the receive interrupt is enabled, the receive data register is full, and no receive error conditions exist. Reading RX clears the pending interrupt. This error-free interrupt can use a fast interrupt service routine for minimum overhead.

2.SSI Receive Data with Exception Status – occurs when the receive interrupt is enabled, the receive data register is full, and a receiver overrun error has occurred. ROE is cleared by first reading the SSISR and then reading RX.

3.SSI Transmit Data – occurs when the transmit interrupt is enabled, the transmit data register is empty, and no transmitter error conditions exist. Writing to TX or the TSR will clear this interrupt. This error-free interrupt may use a fast interrupt service routine for minimum overhead.

4.SSI Transmit Data with Exception Status – occurs when the transmit interrupt is enabled, the transmit data register is empty, and a transmitter underrun error has occurred. TUE is cleared by first reading the SSISR and then writing to TX or the TSR to clear the pending interrupt.

MOTOROLA PORT C 6 - 109

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

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

SYNCHRONOUS SERIAL INTERFACE (SSI)

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 EXTERNAL INTERRUPTS

$000A IRQB EXTERNAL HARDWARE INTERRUPT

$000C SSI RECEIVE DATA

$000E

SSI RECEIVE DATA WITH EXCEPTION STATUS

 

SYNCHRONOUS

 

 

 

SERIAL

 

 

 

 

 

 

 

 

$0010

SSI TRANSMIT DATA

 

INTERFACE

 

 

 

 

 

 

 

 

 

$0012

SSI TRANSMIT DATA WITH EXCEPTION STATUS

 

 

 

 

 

 

 

 

 

 

 

INTERNAL

$0014

SCI RECEIVE DATA

 

 

 

 

 

 

 

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

 

 

INTERFACE

INTERRUPTS

$003A

AVAILABLE FOR HOST COMMAND

 

 

$003C

TIMER

 

 

$003E

ILLEGAL INSTRUCTION

 

 

$0040

AVAILABLE FOR HOST COMMAND

 

 

 

•

 

 

 

•

 

 

 

•

 

 

$007E

AVAILABLE FOR HOST COMMAND

 

 

Figure 6-53 SSI Exception Vector Locations

6 - 110 PORT C MOTOROLA

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

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

SYNCHRONOUS SERIAL INTERFACE (SSI)

 

 

 

 

 

 

SSI CONTROL REGISTER (CRB)

 

 

 

 

 

(READ/WRITE)

 

 

 

 

X:$FFED

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

 

14

13

12

11

10

9

8

 

 

 

 

 

 

 

 

 

 

 

 

 

RIE

 

TIE

RE

TE

MOD

GCK

SYN

FSL1

 

 

 

 

 

 

 

 

 

 

 

SSI

EXCEPTION

MASK

 

 

 

 

SSI EXCEPTION MASK

 

 

 

 

EXCEPTION

 

STARTING

 

ADDRESS

 

 

 

EXCEPTION VECTOR TABLE

 

 

 

 

 

 

 

 

 

 

$0000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$000C SSI RECEIVE DATA

$000E SSI RECEIVE DATA WITH EXCEPTIONS STATUS

$0010 SSI TRANSMIT DATA

$0012 SSI TRANSMIT DATA WITH EXCEPTION STATUS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SSI STATUS REGISTER (SSISR)

 

 

 

 

 

 

(READ ONLY)

 

 

 

 

 

X:$FFFE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

 

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RDF

 

TDE

ROE

TUE

RFS

TFS

IF1

IF0

 

 

 

 

 

 

 

 

 

 

 

 

 

SSI STATUS BITS

RECEIVE

INTERRUPT SERVICE ROUTINE

1.INTERRUPT IS GENERATED WHEN RIE = 1, RDF = 1, AND ROE = 0.

2.PENDING INTERRUPT IS CLEARED BY READING RX.

RECEIVE WITH EXCEPTION STATUS INTERRUPT SERVICE ROUTINE

1.INTERRUPT IS GENERATED WHEN RIE = 1, RDF = 1, AND ROE = 1.

2.ROE IS CLEARED BY READING SSISR FOLLOWED BY:

3.READING RX TO CLEAR PENDING INTERRUPT.

4.APPLICATION-SPECIFIC CODE.

TRANSMIT

INTERRUPT SERVICE ROUTINE

1.INTERRUPT IS GENERATED WHEN TIE = 1, TDF = 1, AND TUE = 0.

2.PENDING INTERRUPT IS CLEARED BY WRITING TO TX OR TSR.

TRANSMIT WITH EXCEPTION STATUS INTERRUPT SERVICE ROUTINE

1.INTERRUPT IS GENERATED WHEN TIE = 1, TDF = 1, AND TUE = 1.

2.TUE IS CLEARED BY READING SSISR FOLLOWED BY:

3.WRITING TO TX OR TSR TO CLEAR PENDING INTERRUPT.

4.APPLICATION-SPECIFIC CODE.

Figure 6-54 SSI Exceptions

MOTOROLA PORT C 6 - 111

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

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