High Frequency Design Considerations
21-8
ADSP-BF537 Blackfin Processor Hardware Reference
To avoid contention, program the turnaround time (bank transition time)
appropriately in the asynchronous memory bank control registers. This
feature allows software to set the number of clock cycles between these
types of accesses on a bank-by-bank basis. Minimally, the External Bus
Interface Unit (EBIU) provides one cycle for the transition to occur.
High Frequency Design Considerations
Because the processor can operate at very fast clock frequencies, signal
integrity and noise problems must be considered for circuit board design
and layout. The following sections discuss these topics and suggest various
techniques to use when designing and debugging signal processing
systems.
Signal Integrity
In addition to reducing signal length and capacitive loading, critical sig-
nals should be treated like transmission lines.
Capacitive loading and signal length of buses can be reduced by using a
buffer for devices that operate with wait states (for example, SDRAMs).
This reduces the capacitance on signals tied to the zero-wait-state devices,
allowing these signals to switch faster and reducing noise-producing cur-
rent spikes. Extra care should be taken with certain signals such as external
memory, read, write, and acknowledge strobes.
Use simple signal integrity methods to prevent transmission line reflec-
tions that may cause extraneous extra clock and sync signals. Additionally,
avoid overshoot and undershoot that can cause long term damage to input
pins.
Some signals are especially critical for short trace length and usually
require series termination. The
CLKIN
pin should have impedance match-
ing series resistance at its driver. SPORT interface signals
TCLK
,
RCLK
,
RFS
,
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 ...