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How to measure battery voltage (8 V to 14 Volts) using ADC12 in MSP430F5635

Jenitta Rex
Intellectual 660 points
Other Parts Discussed in Thread: MSP430F5635

Hi

I am new to micro controller programming .

I want to measure the battery voltage that ranges from 8 V olts to 14 volts .

I believe the the maximum voltage that can be measured using ADC12 of MSP430F5635 is 2.5 Volts.

Then how can I measure this voltage range 8 V to 14 V ?

Thanks in advance

Rexlin

 

 

 

  • 0
    Guru 27285 points

    Jenitta Rex said:
    Then how can I measure this voltage range 8 V to 14 V ?

     Hi Jenitta, I hope you are also new to basic electronic, a resistive voltage divider must apply in front of ADC input to adapt voltage of battery to input range, so I suggest you to have a fixed divider 10:1, this result in a full scale of 25V but you can select 1.5V reference for a 15V full scale.

     Exact conversion of 14 V to 2.5 FS is not recommended due to battery voltage fluctuation and possible fault so a good margin need to be applied.

     On ratio selection also evaluate for binary division or decimal, so one bit of your ADC measure Vref/FS -> 2.5/4096 -> 610.352 uV if you scale by decimal 10:1 one bit equal 6.10352 mV if you scale bynary for example 8.192:1 FS result be 20.48 but one bit  is exactly 500uV.

     Divider ratio can be derived from voltage divider formula:

     VADCFS=VINFS*R1/(R1+R2)   Divider ratio =R1/(R1+R2)

     Regards

     Roberto

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