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DMA Serial Peripheral Interface (DSPI)
31-40
Freescale Semiconductor
31.5.5
Calculation of FIFO Pointer Addresses
Complete visibility of the TX and RX FIFO contents is available through the FIFO registers, and valid
entries can be identified through a memory mapped pointer and a memory mapped counter for each FIFO.
The pointer to the first-in entry in each FIFO is memory mapped. For the TX FIFO, the first-in pointer is
the transmit next pointer (TXNXTPTR). For the RX FIFO, the first-in pointer is the pop next pointer
(POPNXTPTR).
illustrates the concept of first-in and last-in FIFO entries along with the FIFO counter. The
TX FIFO is chosen for the illustration, but the concepts carry over to the RX FIFO. See
”
Section 31.4.2.5, “RX FIFO Buffering Mechanism
”
for details on
the FIFO operation.
Table 31-22. Delay Values
Delay Prescaler Values
(DSPI_CTAR
n
[PBR])
1
3
5
7
D
e
la
y Scaler V
a
lue
s
(D
SPI_C
T
AR
n
[DT])
2
20.0 ns
60.0 ns
100.0 ns
140.0 ns
4
40.0 ns
120.0 ns
200.0 ns
280.0 ns
8
80.0 ns
240.0 ns
400.0 ns
560.0 ns
16
160.0 ns
480.0 ns
800.0 ns
1.1
s
32
320.0 ns
960.0 ns
1.6
s
2.2
s
64
640.0 ns
1.9
s
3.2
s
4.5
s
128
1.3
s
3.8
s
6.4
s
9.0
s
256
2.6
s
7.7
s
12.8
s
17.9
s
512
5.1
s
15.4
s
25.6
s
35.8
s
1024
10.2
s
30.7
s
51.2
s
71.7
s
2048
20.5
s
61.4
s
102.4
s
143.4
s
4096
41.0
s
122.9
s
204.8
s
286.7
s
8192
81.9
s
245.8
s
409.6
s
573.4
s
16384
163.8
s
491.5
s
819.2
s
1.1 ms
32768
327.7
s
983.0
s
1.6 ms
2.3 ms
65536
655.4
s
2.0 ms
3.3 ms
4.6 ms
Содержание MCF54455
Страница 33: ...xxviii Freescale Semiconductor ...
Страница 67: ...Freescale Semiconductor 1 ...
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Страница 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Страница 173: ...Cache 6 28 Freescale Semiconductor ...
Страница 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Страница 207: ...Power Management 9 16 Freescale Semiconductor ...
Страница 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Страница 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Страница 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Страница 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Страница 601: ...Freescale Semiconductor 1 ...
Страница 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Страница 843: ...Freescale Semiconductor 1 ...
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