Serial Communication Performance
A-4
MPC823e REFERENCE MANUAL
MOTOROLA
SERIAL COMMUNICATION
A
PERFORMANCE
A.2 EXAMPLE #1
If the MPC823e is operating at 25MHz with one Ethernet line in half-duplex at 10Mbps, one
38.4Kbd SMC UART, one 57.6Kbd SMC UART, and one USB at 1.5 Mbps, then the
following equation applies.
Any calculation such as this, which is close to one, is considered to be in a gray area and
must be tested with hardware before it is implemented.
A.3 EXAMPLE #2
If a block of 512K is transferred by IDMA in single address mode from memory to a
peripheral, one ASYNC HDLC at 1Mbps, and one SMC UART at 38.4Kbd, then the following
equation applies when the MPC823e is running at 25MHz.
A.4 EXAMPLE #3
For one half-duplex Ethernet channel at 10Mbps and one SMC UART at 115.2Kbd with the
MPC823e running at 40MHz, the following equation applies.
Note:
With IDMA, this process calculates peak communication processor module
usage, not the sustained rate. By nature, IDMA transfers occur in random
intervals and are not consistent bit rates when compared to the serial channel
operation.
10
22
------
38.4
220
-----------
57.6
220
-----------
1.5
24
-------- 0.953=++++
512
5000
-------------
1000
3000
-------------
38.4
220
----------- 0.69=+++
10
22
------
115.2
220
---------------+
25
40
------
× 0.611=
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