Cirrus Logic AN44 - Manual (Page 2)

cable. Figure 1 is a block diagram illustrating
the process. On the top of Figure 1, the
evaluation board CDBXXXX contains digital
interface circuitry which translates signals from
the ADC to three standard serial signals named
FRAME, SCLK and SDATA. The timing and
format of these signals vary from device type to
device type.
In an embedded ADC application, the digital
interface circuit, between the ADC and the
CDBCPATURE circuit card, should be
implemented on a small card attached to the
serial cable as shown at the bottom of Figure 1.
The appropriate digital input signals need to be
identified. A method to connect to these signals
from the embedded system to the cable is then
implemented. The connection scheme varies for
each application and is easy to implement.
The schematic for the digital interface circuitry
is provided with the evaluation board data sheet.
Locate the serial interface connector containing
the signals: +5 V, GND, FRAME, SCLK, and
SDATA on the schematic. Working from this
connector, back to the ADC, identify the
circuitry required to create the serial signals.
This circuitry is implemented on a separate
circuit board, attached to a 10 conductor ribbon
cable with an IDC socket for its CDBCAPTURE
interface. The ADC interface can be any
connector scheme that is easy to implement.
Possible alternatives include stake headers, test
clips, circular connectors, or "D" style
connectors.
A
D
C
INTERFACE
CIRCUIT
EMBEDDED ADC CDBCAPTURE
MODIFIED
SERIAL RIBBON
CABLE
A
D
C
5 V
GND
FRAME
SCLK
SDATA
INTERFACE
CIRCUIT
CDBXXXX EVALUATION BOARD CDBCAPTURE
SERIAL RIBBON
CABLE
Figure 1. CDBCAPTURE INTERFACE
Using The CDBCapture System with Embedded A/D Converters
2 AN44REV2