AN1921 Motorola / Freescale Semiconductor, AN1921 Datasheet - Page 25

• Manufacturer Part Number: AN1921
• Description: AN1921 General DSP568xx Interface Examples using the Embedded SDK
• Manufacturer: Motorola / Freescale Semiconductor

B.2 Data Input
The I/O CLOCK sequence applied to the I/O CLOCK terminal transfers this data to the input data
register.
The I/O CLOCK during this transfer shifts the previous conversion result from the output data register
to DATA OUT. I/O CLOCK receives the input sequence of 8, 12, or 16 clock cycles long depending
on the data-length selection in the input data register. Sampling of the analog input begins on the fourth
falling edge of the input I/O CLOCK sequence and is held after the last falling edge of the I/O CLOCK
sequence. The last falling edge of the I/O CLOCK sequence also takes EOC low and begins the
conversion.
The data input is internally connected to an 8-bit serial-input address and control register. The register
defines the operation of the converter and the output data length. The host provides the data word with
MSB first. Each data bit is clocked in on the rising edge of the I/O CLOCK sequence.
provides the details for the data input-register format.
FUNCTION SELECT
Select Input Channel
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
Interface Examples Using the Embedded SDK
Table B-2.
D7-D4
D3-D2
Field
D1
D0
Table B-1. Fields of Data Input
0
0
0
0
0
0
0
D7
ADDRESS BITS
Analog Channel Address
Data Length
Output MSB or LSB First
Unipolar or Bipolar Output
Input-Register Format
0
0
0
0
1
1
1
D6
(MSB)
D5
0
0
1
1
0
0
1
D4
Description
0
1
0
1
0
1
0
INPUT DATA BYTE
Integrating Devices With the EVM Board
L1
D3
D2
L0
LSBF
D1
(LSB)
D0
BIP
Table B-2
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