Motorola PowerQUICC II MPC8280 Series Reference Manual page 1372

SPI Commands
Table 39-6. RFCR/TFCR Field Descriptions (continued)
Bits Name
6 DTB Data bus indicator.
0 Use 60x bus for SDMA operation.
1 Use local bus for SDMA operation.
7 — Reserved, should be cleared.
39.6 SPI Commands
Table 39-7 lists transmit/receive commands sent to the CP command register (CPCR).
Command
Initializes all transmit parameters in the parameter RAM to their reset state and should be issued
INIT TX
only when the transmitter is disabled. The
PARAMETERS
to reset both the Tx and Rx parameters.
Forces the SPI controller to close the current RxBD and use the next BD for subsequently received
CLOSE RXBD
data. If the controller is not receiving data, no action is taken. Use this command to extract data from
a partially full buffer.
Initializes all receive parameters in the parameter RAM to their reset state. Should be issued only
INIT RX
when the receiver is disabled. The
PARAMETERS
both the Tx and Rx parameters.
39.7 The SPI Buffer Descriptor (BD) Table
As shown in Figure 39-10, BDs are organized into separate RxBD and TxBD tables in
dual-port RAM. The tables have the same basic configuration as for the SCCs and SMCs
and form circular queues that determine the order buffers are transferred. The CP uses BDs
to confirm reception and transmission or to indicate error conditions so that the core knows
buffers have been serviced. The buffers themselves can be placed in external memory or in
any unused parameter area of the dual-port RAM.
39-14
Freescale Semiconductor, Inc.
Table 39-7. SPI Commands
INIT TX AND RX PARAMETERS
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Description
Description
command can also be used
INIT TX AND RX PARAMETERS
command can also be used to reset
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