ADSP-BF537 Blackfin Processor Hardware Reference
10-21
SPI Compatible Port Controllers
software. To clear a sticky bit, the user must write a 1 to the desired bit
position of
SPI_STAT
. For example, if the
TXE
bit is set, the user must write
a 1 to bit 2 of
SPI_STAT
to clear the
TXE
error condition. This allows the
user to read
SPI_STAT
without changing its value.
L
Sticky bits are cleared on a reset, but are not cleared on an SPI
disable.
See
for more information.
Mode Fault Error (MODF)
The
MODF
bit is set in
SPI_STAT
when the
SPISS
input pin of a device
enabled as a master is driven low by some other device in the system. This
occurs in multimaster systems when another device is also trying to be the
master. To enable this feature, the
PSSE
bit in
SPI_CTL
must be set. This
contention between two drivers can potentially damage the driving pins.
As soon as this error is detected, these actions occur:
• The
MSTR
control bit in
SPI_CTL
is cleared, configuring the SPI
interface as a slave
• The
SPE
control bit in
SPI_CTL
is cleared, disabling the SPI system
• The
MODF
status bit in
SPI_STAT
is set
• An SPI error interrupt is generated
These four conditions persist until the
MODF
bit is cleared by software.
Until the
MODF
bit is cleared, the SPI cannot be re-enabled, even as a slave.
Hardware prevents the user from setting either
SPE
or
MSTR
while
MODF
is
set.
When
MODF
is cleared, the interrupt is deactivated. Before attempting to
re-enable the SPI as a master, the state of the
SPISS
input pin should be
checked to make sure the pin is high. Otherwise, once
SPE
and
MSTR
are
set, another mode fault error condition immediately occurs.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...