MPC8280 datasheet(886/1386 Pages) FREESCALE

886 / 1386 page

Serial Management Controllers (SMCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

28-32

Freescale Semiconductor

28.5.3.2

SMC GCI C/I Channel Reception Process

The SMC receiver continuously monitors the C/I channel. When it recognizes a change in the data and this

value is received in two successive frames, it is interpreted as valid data. This is called the double last-look

method. The CP stores the received data byte in the C/I RxBD and a maskable interrupt is generated. If the

SMC is configured to support SCIT channel 1, the double last-look method is not used.

28.5.4

SMC GCI Commands

The commands in Table 28-18 are issued to the CPCR.

28.5.5

SMC GCI Monitor Channel RxBD

This BD, seen in Figure 28-15, is used by the CP to report information about the monitor channel receive

byte.

Table 28-19 describes SMC monitor channel RxBD fields.

Table 28-18. SMC GCI Commands

Command

Description

INIT TX AND RX

PARAMETERS

Initializes transmit and receive parameters in the parameter RAM to their reset state. It is especially

useful when switching protocols on a given serial channel.

TRANSMIT

ABORT REQUEST

This receiver command can be issued when the MPC8280 implements the monitor channel protocol.

When it is issued, the MPC8280 sends an abort request on the A bit.

TIMEOUT

This transmitter command can be issued when the MPC8280 implements the monitor channel protocol.

It is usually issued because the device is not responding or A bit errors are detected. The MPC8280

sends an abort request on the E bit at the time this command is issued.

0123

Offset + 0

—DATA

Figure 28-15. SMC Monitor Channel RxBD

Table 28-19. SMC Monitor Channel RxBD Field Descriptions

Bits

Name

Description

Empty.

0 The CP clears E when the byte associated with this BD is available to the core.

1 The core sets E when the byte associated with this BD has been read.

Last (EOM). Valid only for monitor channel protocol and is set when the EOM indication is received

on the E bit. Note that when this bit is set, the data byte is invalid.

Error condition. Valid only for monitor channel protocol. Set when an error occurs on the monitor

channel protocol. A new byte is sent before the SMC acknowledges the previous byte.

Data mismatch. Valid only for monitor channel protocol. Set when two different consecutive bytes

are received; cleared when the last two consecutive bytes match. The SMC waits for the reception

of two identical consecutive bytes before writing new data to the RxBD.

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