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ADuC7060 _ADC4 output noise ?

Question asked by Terumasa on Mar 14, 2017
Latest reply on May 4, 2017 by barryzhang

Hello

 

Please let me know your advice about ADC4 output of ADuC7060.

Our customer uses EVAL-ADuC7060 at below condition.

 

Problem

Primary channel and Auxiliary channel is measured  alternately.

Output data of Primary channel is OK  ,

but the data of Auxiliary channel is periodically swing about  12274000LSB +- 1000LSB.

 

When auxiliary channel only is measured ,   ( primary channel is disabled)

above problem is not appeared  and result is about 12274000 LSB +- 100LSB

 

 

Question

Is there any limitation of using both primary channel and auxiliary channel ?

If you need measurement data , please let me know your e-mail address because it is cutomer's data.

 

Measurement sequence

Measured channel is below sequence.

ADC0:1 - > ADC4 - > ADC2-> ADC4 -> ADC3  -> ADC4   - >  ADC0:1  ....

 

Channel settings

ADC0:1  = RTD

ADC2 and ADC3 : another sensor output voltage

ADC4:   0.88V from reference  voltage generator

ADC5 is connected to AGND.

 

Board switch setting

dipswS4-1~S4-4:on

Other switch: Open

 

Register settings of both channel measurement

ADCMDE = 0x81;

ADCMSKI = 0x03;

ADC0CON

ADC0-1: 0x8414

ADC2:   0x8580

ADC3:   0x85C0

ADC1CON

ADC4:   0x8B00

ADCFLT = 0xC0FF;

ADCCFG = 0x0000;

IEXCON = 0x42;

 

Register settings of auxiliary channel  only measurement

Below change from above settings

ADCMSKI = 0x02; 

ADC0CON = 0x0000

 

Please let me know your advice.

 

Best Regards,

Terumasa

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