
Unique Information for the ADSP-BF59x Processor
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ADSP-BF59x Blackfin Processor Hardware Reference
Clock Gating Functionality
A proper interface to many precision A/D converters requires that digital
noise be eliminated during conversion quiet zones. These quiet zones can
be created by using a gated clock and a guard-banded convert signal wave-
form. One way to do this is through external logic that properly interfaces
the converter to a SPORT on the processor.
The ADSP-BF59x family has integrated “gated clock” hardware that elim-
inates the need for this external logic and allows the SPORT to interface
directly to the converter. This logic constitutes a four-wire interface that is
flexible enough to handle many serial A/D converters with different clock
rates, converter rates, and converter modes.
Consider an ADC whose digital interface consists of the following four
wires:
•
CNV
– convert signal
•
SCK
– data clock
•
DIN
– configuration data input
•
SDO
– conversion result read data
An ADSP-BF59x processor’s SPORT can connect to this converter in the
following manner:
• Connect
CNV
to SPORT TFS (transmit frame sync)
• Connect
SCK
to SPORT TSCLK (transmit SPORT clock)
• Connect
DIN
to SPORT DTPRI (primary transmit data)
• Connect
SDO
to SPORT DRPRI (primary receive data)
Key requirements of the converter are that the digital pins remain quiet
during critical times of the conversion process. In order to meet this
requirement
SCK
must be active only when necessary to read conversion
Содержание ADSP-BF59x Blackfin
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