Добавил:
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
БЭМЗ полищук доки / Склад / Datasheet_LM3S6965.pdf
Скачиваний:
10
Добавлен:
21.12.2020
Размер:
6.13 Mб
Скачать

LM3S6965 Microcontroller

Register 3: SSI Data (SSIDR), offset 0x008

SSIDR is the data register and is 16-bits wide. When SSIDR is read, the entry in the receive FIFO (pointed to by the current FIFO read pointer) is accessed. As data values are removed by the SSI receivelogicfromtheincomingdataframe,theyareplacedintotheentryinthereceiveFIFO(pointed to by the current FIFO write pointer).

When SSIDR is written to, the entry in the transmit FIFO (pointed to by the write pointer) is written to. Data values are removed from the transmit FIFO one value at a time by the transmit logic. It is loadedintothetransmitserialshifter,thenseriallyshiftedoutontothe SSITx pinattheprogrammed bit rate.

When a data size of less than 16 bits is selected, the user must right-justify data written to the transmit FIFO. The transmit logic ignores the unused bits. Received data less than 16 bits is automatically right-justified in the receive buffer.

When the SSI is programmed for MICROWIRE frame format, the default size for transmit data is eightbits(themostsignificantbyteisignored). Thereceivedatasizeiscontrolledbytheprogrammer. The transmit FIFO and the receive FIFO are not cleared even when the SSE bit in the SSICR1 register is set to zero. This allows the software to fill the transmit FIFO before enabling the SSI.

SSI Data (SSIDR)

SSI0 base: 0x4000.8000

Offset 0x008

Type R/W, reset 0x0000.0000

 

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

reserved

 

 

 

 

 

 

 

Type

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

DATA

 

 

 

 

 

 

 

Type

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Bit/Field

Name

Type

Reset

Description

31:16

reserved

RO

0x0000

Software should not rely on the value of a reserved bit. To provide

 

 

 

 

compatibility with future products, the value of a reserved bit should be

 

 

 

 

preserved across a read-modify-write operation.

15:0

DATA

R/W

0x0000

SSI Receive/Transmit Data

 

 

 

 

A read operation reads the receive FIFO. A write operation writes the

 

 

 

 

transmit FIFO.

Software must right-justify data when the SSI is programmed for a data size that is less than 16 bits. Unused bits at the top are ignored by the transmit logic. The receive logic automatically right-justifies the data.

November 16, 2008

371

Preliminary

Synchronous Serial Interface (SSI)

Register 4: SSI Status (SSISR), offset 0x00C

SSISR isastatusregisterthatcontainsbitsthatindicatetheFIFOfillstatusandtheSSIbusystatus.

SSI Status (SSISR)

SSI0 base: 0x4000.8000

Offset 0x00C

Type RO, reset 0x0000.0003

 

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

reserved

 

 

 

 

 

 

 

Type

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

reserved

 

 

 

 

 

BSY

RFF

RNE

TNF

TFE

Type

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

R0

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

1

Bit/Field

Name

Type

Reset

Description

31:5

reserved

RO

0x00

Software should not rely on the value of a reserved bit. To provide

 

 

 

 

compatibility with future products, the value of a reserved bit should be

 

 

 

 

preserved across a read-modify-write operation.

4

BSY

RO

0

SSI Busy Bit

 

 

 

 

The BSY values are defined as follows:

 

 

 

 

Value Description

0 SSI is idle.

1 SSI is currently transmitting and/or receiving a frame, or the transmit FIFO is not empty.

3

RFF

RO

0

SSI Receive FIFO Full

The RFF values are defined as follows:

Value Description

0 Receive FIFO is not full.

1 Receive FIFO is full.

2

RNE

RO

0

SSI Receive FIFO Not Empty

The RNE values are defined as follows:

Value Description

0 Receive FIFO is empty.

1 Receive FIFO is not empty.

1

TNF

RO

1

SSI Transmit FIFO Not Full

The TNF values are defined as follows:

Value Description

0 Transmit FIFO is full.

1 Transmit FIFO is not full.

372

November 16, 2008

Preliminary

LM3S6965 Microcontroller

Bit/Field

Name

Type

Reset

Description

0

TFE

R0

1

SSI Transmit FIFO Empty

 

 

 

 

The TFE values are defined as follows:

 

 

 

 

Value

Description

 

 

 

 

0

Transmit FIFO is not empty.

 

 

 

 

1

Transmit FIFO is empty.

November 16, 2008

373

Preliminary

Synchronous Serial Interface (SSI)

Register 5: SSI Clock Prescale (SSICPSR), offset 0x010

SSICPSR is the clock prescale register and specifies the division factor by which the system clock must be internally divided before further use.

The value programmed into this register must be an even number between 2 and 254. The least-significant bit of the programmed number is hard-coded to zero. If an odd number is written to this register, data read back from this register has the least-significant bit as zero.

SSI Clock Prescale (SSICPSR)

SSI0 base: 0x4000.8000

Offset 0x010

Type R/W, reset 0x0000.0000

 

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

 

 

 

 

 

 

 

 

reserved

 

 

 

 

 

 

 

Type

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

RO

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

 

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

reserved

 

 

 

 

 

 

CPSDVSR

 

 

 

Type

RO

RO

RO

RO

RO

RO

RO

RO

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

Reset

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Bit/Field

Name

Type

Reset

Description

31:8

reserved

RO

0x00

Software should not rely on the value of a reserved bit. To provide

 

 

 

 

compatibility with future products, the value of a reserved bit should be

 

 

 

 

preserved across a read-modify-write operation.

7:0

CPSDVSR

R/W

0x00

SSI Clock Prescale Divisor

 

 

 

 

This value must be an even number from 2 to 254, depending on the

 

 

 

 

frequency of SSIClk. The LSB always returns 0 on reads.

374

November 16, 2008

Preliminary

Соседние файлы в папке Склад