DSP56857 datasheet(583/662 Pages) FREESCALE

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Sheet

56F853/854/855/857/858 Digital Signal Controller User Manual, Rev. 4

B-81

Freescale Semiconductor

Preliminary

14 of 16

denotes Reserved Bits

ESSI FIFO

Control/Status

Base + $B

Bits

Read

RFCNT

TFCNT

RFWM

TFWM

Write

Reset

0000

1000

0001

7 - 4

RFWM

Receive FIFO Full Watermark

This bit field controls the threshold setting of the Receive FIFO Full Flag will be set. RFF is set

whenever the data level in the RXFIFO reaches the selected threshold. The following data

shows the status of RFF for all data levels of the RXFIFO.

0000 Reserved

0001

RFF set when at least 1 data word has been written to the RXFIFO. Set when RXFIFO =

1, 2, 3, 4, 5, 6, 7, or 8 data words

0010

RFF set when 2 or more data word has been written to the RXFIFO.

Set when RXFIFO = 2, 3, 4, 5, 6, 7, or 8 data words

0011

RFF set when 3 or more data word has been written to the RXFIFO.

Set when RXFIFO = 3, 4, 5, 6, 7, or 8 data words

0100

RFF set when 4 or more data word has been written to the RXFIFO.

Set when RXFIFO = 4, 5, 6, 7, or 8 data words

0101

RFF set when 5 or more data word has been written to the RXFIFO.

Set when RXFIFO = 5, 6, 7, or 8 data words

0110

RFF set when 6 or more data word has been written to the RXFIFO.

Set when RXFIFO = 6, 7, or 8 data words

0111

RFF set when 7 or more data word has been written to the RXFIFO.

Set when RXFIFO = 7, or 8 data words

1000

RFF set when 8 data word has been written to the RXFIFO.

Set when RXFIFO = 8 data words

3 - 0

TDWM

Transmit FIFO Empty Watermark

This bit field controls the threshold where the Transmit FIFO Empty flag is set. The following

data provides the status of TFE for all data levels of the TXFIFO.

0000 Reserved

0001

TFE set when there is 1 empty slot in TXFIFO. (Default) Transmit FIFO empty is set

when TXFIFO = <7 data

0010

TFE set when there is 2 or more empty slots in TXFIFO. Transmit FIFO empty is set

when TXFIFO = <6 data

0011

TFE set when there is 3 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <5 data

0100

TFE set when there is 4 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <4 data

0101

TFE set when there is 5 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <3 data

0110

TFE set when there is 6 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <2 data

0111

TFE set when there is 7 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <1 data

1000

TFE set when there is 8 empty slot in TXFIFO. Transmit FIFO empty is set when

TXFIFO = <0 data

ESSI FIFO Control/Status Register (SFCSR) continued

ESSI

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