CS5532-AS datasheet(37/52 Pages) CIRRUS

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CS5531/32/33/34

DS289PP5

Table 2. Conversion Timing for Continuous Mode

2.6.3. Examples of Using CSRs to Perform

Conversions and Calibrations

Any time a calibration or conversion command is

issued (C, MC, and CC2-CC0 bits must be properly

set), the CSRP2-CSRP0 bits in the command byte

are used as pointers to address one of the Setups in

the channel-setup registers (CSRs). Table 3 details

the address decoding of the pointer the bits.

The examples that follow detail situations that a

user might encounter when acquiring a conversion

or calibrating the converter. These examples as-

sume that the CSRs are programmed with the fol-

lowing physical channel order: 4,1,1,2, 4,3,4,4.

A physical channel is defined as the actual input

channel (AIN1 to AIN4) to which an external sig-

nal is connected.

Example 1: Single conversion using Setup 1. The

command issued is ‘10000000’. This instructs the

converter to perform a single conversion referenc-

ingSetup1(CSRP2 - CSRP0= ‘000’) In this ex-

ample, Setup 1 points to physical channel 4. After

the command is received and decoded, the ADC

performs a conversion on physical channel 4 and

SDO falls to indicate that the conversion is com-

plete. To read the conversion, 40 SCLKs are then

required. Once the conversion data has been read,

the serial port returns to the command mode.

Example 2: Continuous conversions using Setup 3.

The command issued is ‘11010000’. This instructs

the converter to perform continuous conversions

referencingSetup3(CSRP2- CSRP0= ‘010’). In

this example, Setup 3 points to physical channel 1.

After the command is received and decoded, the

ADC performs a conversion on physical channel 1

and SDO falls to indicate that the conversion is

complete. The user now has three options. The user

can acquire the conversion and remain in this

mode, acquire the conversion and exit this mode, or

ignore the conversion and wait for a new conver-

sion at the next update interval, as detailed in the

continuous conversion section.

Example 3: Calibration using Setup 4. This exam-

ple assumes that the OGS bit in the Configuration

‘10011001’. This instructs the converter to perform

a self offset calibration referencing Setup 4

(CSRP2 - CSRP0 = ‘011’). In this example, Setup

4 points to physical channel 2. After the command

is received and decoded, the ADC performs a self

offset calibration on physical channel 2 and SDO

falls to indicate that the calibration is complete. To

perform additional calibrations, more commands

must be issued.

Note:

The CSRs need not be written. If they are not

1010

17848 ± 8

5120

1011

28088 ± 8

10240

1100

48568 ± 8

20480

0000

107434 ± 10

49152

0001

205738 ± 10

98304

0010

402346 ± 10

196608

0011

795562 ± 10

393216

0100

1581994 ± 10

786432

1000

2966 ± 10

1536

1001

15274 ± 10

3072

1010

21418 ± 10

6144

1011

33706 ± 10

12288

1100

58282 ± 10

24576

(CSRP2-CSRP0)

CSR Location

Setup

000

CSR #1

001

CSR #1

010

CSR #2

011

CSR #2

100

CSR #3

101

CSR #3

110

CSR#4

111

CSR #4

Table 3. Command Byte Pointer

FRS (WR3-WR0)

Clock Cycles

(First Conversion)

Clock Cycles

(All Other

Conversions)

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