
B-80
DSP56F801/803/805/807 User’s Manual
MOTOROLA
Preliminary
Application:
Date:
Programmer:
Sheet
C
B
14 of 16
denotes Reserved Bits
ESSI FIFO
Control/Status
Register (SFCSR)
Base + $8
Bits
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Read
RFCNT
TFCNT
RFWM
TFWM
Write
RESET
0000
1000
0000
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