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Synchronous Serial Interface (SSI)
Freescale Semiconductor
27-31
indicates the status of the Transmit FIFO Empty flag, with different settings of the Transmit
FIFO WaterMark bits and varying amounts of data in the Tx FIFO.
15–12
RFCNT0[3:0]
Receive FIFO Counter 0. These bits indicate the number of data words in Receive FIFO 0. Refer to
for details regarding settings for receive FIFO counter bits.
11–8
TFCNT0[3:0]
Transmit FIFO Counter 0. These bits indicate the number of data words in Transmit FIFO 0. Refer to
for details regarding settings for transmit FIFO counter bits.
7–4
RFWM0[3:0]
Receive FIFO Full WaterMark 0. These bits control the threshold at which the RFF0 flag will be set. The
RFF0 flag is set whenever the data level in Rx FIFO 0 reaches the selected threshold. Refer to
for details regarding settings for receive FIFO watermark bits.
3–0
TFWM0[3:0]
Transmit FIFO Empty WaterMark 0. These bits control the threshold at which the TFE0 flag will be set.
The TFE0 flag is set whenever the empty slots in Tx FIFO exceed or are equal to the selected threshold.
Refer to
for details regarding settings for transmit FIFO watermark bits.
Table 27-18. Status of Transmit FIFO Empty Flag
Transmit FIFO Watermark
(TFWM)
Number of data in Tx-Fifo
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
2
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
3
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
4
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
5
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
6
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
7
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
8
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
9
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
10
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
11
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
12
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
13
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
14
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 27-13. SSI FIFO Control/Status Register Field Descriptions (continued)
Field
Description
Summary of Contents for MCF54455
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