ADSP-BF537 Blackfin Processor Hardware Reference
10-43
SPI Compatible Port Controllers
• Slave select value (
FLGx
) bits
When a
PFx
pin is configured as a slave select output, the
FLGx
bits
can determine the value driven onto the output. If the
CPHA
bit in
SPI_CTL
is set, the output value is set by software control of the
FLGx
bits. The SPI protocol permits the slave select line to either
remain asserted (low) or be deasserted between transferred words.
The user must set or clear the appropriate
FLGx
bits. For example,
to drive
PJ10
as a slave select,
FLS3
in
SPI_FLG
must be set. Clearing
FLG3
in
SPI_FLG
drives
PJ10
low; setting
FLG3
drives
PJ10
high. The
PJ10
pin can be cycled high and low between transfers by setting
and clearing
FLG3
. Otherwise,
PJ10
remains active (low) between
transfers.
If
CPHA
= 0, the SPI hardware sets the output value and the
FLGx
bits are ignored. The SPI protocol requires that the slave select be
deasserted between transferred words. In this case, the SPI hard-
ware controls the pins. For example, to use
PJ10
as a slave select
pin, it is only necessary to set the
FLS3
bit in
SPI_FLG
. It is not nec-
essary to write to the
FLG3
bit, because the SPI hardware
automatically drives the
PJ10
pin.
Figure 10-14. SPI Status Register
15 14
13 12
11 10
9
8
7
6
5
4
3
2
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset = 0x0001
SPIF (SPI Finished) - RO
Set when SPI single word
transfer complete
MODF (Mode Fault Error) -
W1C
Set in a master device when
some other device tries to
become the master
TXE (Transmission Error) -
W1C
Set when transmission
occurred with no new data in
SPI_TDBR
SPI Status Register (SPI_STAT)
TXCOL (Transmit Collision Error) - W1C
When set, corrupt data may
have been transmitted
RXS (RX Data Buffer Status) - RO
0 - Empty
1 - Full
RBSY (Receive Error) - W1C
Set when data is received with
receive buffer full
TXS (SPI_TDBR Data Buffer Status) - RO
0 - Empty
1 - Full
0xFFC0 0508
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 ...