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12 bits adc pic microcontroller

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alkhafaaf12

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please guys I am dieing to fine circuit and code that can convert ( 0 to 10 volts ) with accuracy
of 1 mv ,,, I need this for a motor that will switch on at every increase of 2.5 Milli volt
HELP ME PLEAAAASE
 

Easyrider83

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You better explain more detaily what exactly do you developing and what for.
Because at this moment it looks like something impossible. Even with 24 bit ADC 1mV with DC motor sounds... not relible.
 

horace1

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please guys I am dieing to fine circuit and code that can convert ( 0 to 10 volts ) with accuracy
of 1 mv ,,, I need this for a motor that will switch on at every increase of 2.5 Milli volt
HELP ME PLEAAAASE
if you are looking for a resolution of 2.5mVolts in 10 volts 12bit ADC will just do it
if 1mvolt you are looking at a 16bit ADC
have a look at the Microchip product selector
http://www.microchip.com/maps/microcontroller.aspx

with this sort of resolution you will require good power supply, filtering, PCB layout, etc
have a look at application notes
http://www.microchip.com/wwwcategory/TaxonomySearch.aspx?show=Application Notes&ShowField=no
 
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alkhafaaf12

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what I need is a circuit and source code if possible , I need to be measuring a sensor level that operates from 0 to 10 volt ,,
in my micro controller I need to check this and devide the range to 4000 steps i.e 10v/4000=2.5mv
and depending on that I will be switching a relay ,, bou dont worry about that I know the rest
 

horace1

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what I need is a circuit and source code if possible , I need to be measuring a sensor level that operates from 0 to 10 volt ,,
in my micro controller I need to check this and devide the range to 4000 steps i.e 10v/4000=2.5mv
and depending on that I will be switching a relay ,, bou dont worry about that I know the rest
a possible approach is to get a low cost development board and experiment with it, e.g. Microchip's microstick
http://www.microchip.com/Developmenttools/ProductDetails.aspx?PartNO=DM330013

on the page is a link the 'Microstick - Temperature sensor project'
http://ww1.microchip.com/downloads/en/DeviceDoc/Temp_Sensor.zip

which uses a PIC24HJ64GP502 to sample the 12bit ADC

the microstick has an onboard programmer and a header to plug into your own prototype board, e.g. with external circuits to convert your 10volt signal to a range suitable for the ADC
 

Issak Sdu

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actually to be accurate, a 12bits ADC offers only (10V/2^12 = 0,0024 V, thats 2.4mV)

the closest number of bits that allows you to reach 1mV accuracy is 13bits or 14bits
13bits => 1.2 mV
14bits => 0.6mV

the only way to get that is to use a dedicated external 16bits ADC, because i don't know any uC including such ADC.
 

horace1

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there are a number of micros with 16bit ADCs, e.g. the PIC18F87J72 and some PIC24s such as PIC24FJ128GC010
but I think 2.5mV in 10volt is the requirement which 12bit should do
 

Issak Sdu

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there are a number of micros with 16bit ADCs, e.g. the PIC18F87J72 and some PIC24s such as PIC24FJ128GC010
thank you for this information, i didn't check the link to the microchip's uC map
 

hobbyckts

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For this accuracy you need to go with the ADC which is having more than 16 bits.
 

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