ADSP-BF535 Blackfin Processor Hardware Reference
10-33
SPI Compatible Port Controllers
If the transmit buffer remains empty or the receive buffer remains full, the
device operates according to the states of the
SZ
and
GM
bits in
SPIx_CTL
. If
SZ = 1
and the transmit buffer is empty, the device repeatedly transmits 0s
on the
MOSI
pin. One word is transmitted for each new transfer initiate
command. If
SZ = 0
and the transmit buffer is empty, the device repeat-
edly transmits the last word it transmitted before the transmit buffer
became empty. If
GM = 1
and the receive buffer is full, the device contin-
ues to receive new data from the
MISO
pin, overwriting the older data in
the
SPIx_RDBR
buffer. If
GM = 0
and the receive buffer is full, the incoming
data is discarded and
SPIx_RDBR
is not updated.
Transfer Initiation From Master (Transfer Modes)
When a device is enabled as a master, the initiation of a transfer is defined
by the two
TIMOD
bits of
SPIx_CTL
. Based on those two bits and the status
of the interface, a new transfer is started upon either a read of
SPIx_RDBR
or a write to
SPIx_TDBR
. Transfer initiation is summarized in
Table 10-19
.
Table 10-19. Transfer Initiation
TIMOD
Function
Transfer Initiated Upon
Action, Interrupt
00
Transmit and
Receive
Initiate new single-word trans-
fer upon read of SPIx_RDBR
and previous transfer com-
pleted
Interrupt active when receive
buffer is full
Read of SPIx_RDBR clears
interrupt
01
Transmit and
Receive
Initiate new single-word trans-
fer upon write to SPIx_TDBR
and previous transfer com-
pleted
Interrupt active when transmit
buffer is empty
Writing to SPIx_TDBR clears
interrupt
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...