ADC convertion when input 0 voltage

[ivancolla9]

Posted on February 29, 2016 at 16:12

Good morning to everyone,

I am trying to understand a possible problem I have with tha AD converter of the SPC56ELxx.

I am working on a board where an input current is used to set an input voltage to trhe ADC converter of the micro controller. 

The ADC seems to work fine: I tested the vlaues in the channel data and they seem right.

But if the input voltage is 0, the AD converter give me a valid DATA, 0x2BB. 

The circuit should  give a voltage proportional to the input current, so, if the current is 0, I expect to read 0 on the ADC channel data.

Is there some characteristic of the ADC converter that I don't know, so that, if the input voltage is 0, it write in the data channel a different value (something like a low treshold)?

Thanks,

Ivan

#ad-converter #low-treshold

[Erwan YVIN]

Posted on April 08, 2016 at 13:57

Hello Ivan ,

did you solve the issue ?

i have no problem onSPC56ELxx OS-Less ADC Test Application for DiscoveryPlus

the ADC Conversion is well 0x0 or 0x1.

(cf screenshot)

for standard channel, i recommend you to increase INPSAMP.

Best regards

Erwan

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Attachments :

2016-04-08_135453.png : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HtZg&d=%2Fa%2F0X0000000aRv%2FTJPG9LN0xDNrV0gsb1Z0YrX_exlnoC9g1S0sJAKZ3H8&asPdf=false

[ivancolla9]

Posted on May 03, 2016 at 17:42

Hello Erwan,

I worked on the problem and discovered that it was caused by the external circuitry on wich the controller is embedded. I learned how to manage the ADC and now I have no problems.

Regards,

Ivan