Freescale Semiconductor MSC8156 Evaluation Module MSC8156EVM MSC8156EVM Manual Do Utilizador

Freescale Semiconductor

 

16-81

There are many ways in which software can interact with the message controller. One example 
sequence of events to start and complete a transfer in Direct mode is as follows:

Poll the OMxSR[MUB] bit to ensure that the outbound message controller is not busy.

Clear the following OMxSR status bits (see  Table 16-104, OMxSR Field Descriptions, 
on page 16-197):

•

MER

•

RETE 

•

PRT]

•

TE

•

QOI

•

QFI

•

EOMI

•

QEI

Initialize the following registers:

•

Source address (OMxSAR)

•

Destination port (OMxDPR)

•

Destination attributes (OMxDATR)

•

Retry error threshold (OMxRETCR)

•

Double-word count (OMxDCR). 

If multicast mode is enabled (OMxMR[MM]), initialize the multicast group and list in 
OMxMGR and OMxMLR.

Initialize the outbound message mode register message unit transfer mode bit, 
OMxMR[MUTM] = 1, to indicate direct mode. Other control parameters must also be 
initialized in the mode register.

Clear and then set the mode register message unit start bit, OMxMR[MUS], to start the 
message transfer. 

The outbound message controller sets the OMxSR[MUB] bit to indicate that the 
message transfer is in progress. 

The outbound message controller reads a message segment from local memory using the 
source address register (OMxSAR).

If a message has multiple segments, the outbound message controller reads the other 
message segments from local memory. 

After the message read to local memory completes, the message is sent.