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MPC563XM Reference Manual, Rev. 1
1210
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
26.6.4
Calculation of FIFO Pointer Addresses
The user has complete visibility of the TX and RX FIFO contents 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 26.5.3.4, “Transmit First In First Out (TX FIFO) Buffering Mechanism
,” and
Section 26.5.3.5, “Receive First In First Out (RX FIFO) Buffering Mechanism
,” for details on the FIFO
operation.
Table 26-43. Delay Values
Delay Prescaler Values
1
3
5
7
D
e
la
y Sc
al
er
V
a
lu
e
s
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
μ
s
32
320.0 ns
960.0 ns
1.6
μ
s
2.2
μ
s
64
640.0 ns
1.9
μ
s
3.2
μ
s
4.5
μ
s
128
1.3
μ
s
3.8
μ
s
6.4
μ
s
9.0
μ
s
256
2.6
μ
s
7.7
μ
s
12.8
μ
s
17.9
μ
s
512
5.1
μ
s
15.4
μ
s
25.6
μ
s
35.8
μ
s
1024
10.2
μ
s
30.7
μ
s
51.2
μ
s
71.7
μ
s
2048
20.5
μ
s
61.4
μ
s
102.4
μ
s
143.4
μ
s
4096
41.0
μ
s
122.9
μ
s
204.8
μ
s
286.7
μ
s
8192
81.9
μ
s
245.8
μ
s
409.6
μ
s
573.4
μ
s
16384
163.8
μ
s
491.5
μ
s
819.2
μ
s
1.1 ms
32768
327.7
μ
s
983.0
μ
s
1.6 ms
2.3 ms
65536
655.4
μ
s
2.0 ms
3.3 ms
4.6 ms