ADSP-BF537 Blackfin Processor Hardware Reference
21-9
System Design
and
TFS
should use some termination. Although the serial ports may be
operated at a slow rate, the output drivers still have fast edge rates and for
longer distances the drivers often require resistive termination located at
the source. (Note also that
TFS
and
RFS
should not be shorted in
multi-channel mode.) On the PPI interface, the
PPI_CLK
and
SYNC
signals
also benefit from these standard signal integrity techniques. If these pins
have multiple sources, it will be difficult to keep the traces short. Consider
termination of SDRAM clocks, control, address, and data to improve sig-
nal quality and reduce unwanted EMI.
Adding termination to fix a problem on an existing board requires delays
for new artwork and new boards. A transmission line simulator is recom-
mended for critical signals. IBIS models are available from Analog Devices
Inc. that will assist signal simulation software. Some signals can be cor-
rected with a small zero or 22 ohm resistor located near the driver. The
resistor value can be adjusted after measuring the signal at all endpoints.
For details, see the reference sources in
for suggestions on transmission line termination.
Other recommendations and suggestions to promote signal integrity:
• Use more than one ground plane on the Printed Circuit Board
(PCB) to reduce crosstalk. Be sure to use lots of vias between the
ground planes.
• Keep critical signals such as clocks, strobes, and bus requests on a
signal layer next to a ground plane and away from or laid out per-
pendicular to other non-critical signals to reduce crosstalk.
• Experiment with the board and isolate crosstalk and noise issues
from reflection issues. This can be done by driving a signal wire
from a pulse generator and studying the reflections while other
components and signals are passive.
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 ...