Example : ADC

ADC components of OSS-EC

In this section, we will use the OSS-EC ADC component as an example.

  • Block diagram of ADC components and OSS-EC software ( fig.1 )
  • OSS-EC flowchart for ADC components ( fig.2)
physical value
vi Sensor output signal
ai      Circuit output voltage
PCMPProgram component of OSS-EC
MPMicrocontroller unit program
ADC unit program
ai = f(ch)
CP      
Circuit/IC components program
Conversion formula from circuit output voltage to sensor output signal value
vi = f(ai)
SP      System components program
Conversion formula from sensor output signal value to physical value
y = f(vi)

The conversion formula for vi shall be as follows.

vi = f(ai) = ai * ADC_vdd / ( 2ADC_bit )× K_tc

ADC_Vdd Sensor supply voltage [V]
ADC_bit     
ADC conversion of MPU Bit number
CAUTION:When Mbed is selected, 16bit is fixed
K_tc      Circuit/IC transformer circuit constants

The conversion formula for y is as follows. ( Liner conversion )
Let it be a linear transformation equation.

y = f(vi) =( vi – x_offset ) / k_gain + y_offset

x_offset  Voltage Offset [V]
k_gain      Voltage/Physical Value Conversion Constant
y_offset     physical value Offset

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