SPI Data Transfer Operations
10-16
ADSP-2126x SHARC Processor Hardware Reference
If
SENDZ
= 0, it repeatedly transmits the contents of the
TXSPI
register. The
TUNF
underrun condition cannot generate an error interrupt in this mode.
For receive DMA in master mode the
SPICLK
stops only when the
FIFO and
RXSPI
buffer is full (even if the DMA count is zero).
Therefore,
SPICLK
runs for an additional five word transfers filling
junk data in the FIFO and the
RXSPI
buffer. This data must be
cleared before a new DMA is initiated.
A master SPI DMA sequence may involve back-to-back transmission
and/or reception of multiple DMA transfers. The SPI controller supports
such a sequence with minimal processor core interaction.
Master Transfer Preparation
When the processor is enabled as a master, the initiation of a transfer is
defined by the two bit fields (bits 1–0) of
TIMOD
in the
SPICTL
register.
Based on these two bits and the status of the interface, a new transfer is
started upon either a read of the
RXSPI
register or a write to the
TXSPI
reg-
ister. This is summarized in
.
Table 10-1. Transfer Initiation
TIMOD
Function
Transfer Initiated Upon
Action, Interrupt
00
Transmit and
Receive
Initiate new single word
transfer upon read of
RXSPI and previous trans-
fer completed.
The SPI interrupt is latched in every
core clock cycle in which the RXSPI
buffer has a word in it.
Emptying the RXSPI buffer or dis-
abling the SPI port at the same time
(SPIEN = 0) stops the interrupt latch.
01
Transmit and
Receive
Initiate new single word
transfer upon write to
TXSPI and previous trans-
fer completed.
The SPI interrupt is latched in every
core clock cycle in which the TXSPI
buffer is empty.
Writing to the TXSPI buffer or dis-
abling the SPI port at the same time
(SPIEN = 0) stops the interrupt latch.
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...