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MSP430FR6043: the convertion between uss adc capture value and real SDHS analog input

Part Number: MSP430FR6043
Other Parts Discussed in Thread: MSP430FR6041, MSP430FR5043, MSP430FR5041

Hi, there is a question about the convertion between uss adc capture value and real SDHS analog input in MSP430FR6043.

    from SDHS example code in "MSP430FR6043_MSP430FR6041_MSP430FR5043_MSP430FR5041_Code_Examples" , I get a formula about the convertion between uss adc capture value and real SDHS analog input.

  it is as below,

// V = (adc_code * (f_s/2))/(gain*7FF) + Bias
// where,adc_code is the ADC result(16-Bit Signed Int),f_s = .755V(Full-scale voltage),
// gain = 10^(0.1/20)) = approximately 1, Bias = .9V, 7FF = 2047

  question1: why f_s is 0.755v? 

 I search the forums  and get some information about the SDHS convertion.

It seems the Full scale is +-500mv centered on the Rx Bias,and the maximum input signal range is 1000mv. 

If Rx Bias is set to be 0.9v,the range will be 0.4v~1.4v.

  question2: what is the exact input signal range? 

thanx。

  • Hi,

    You can consider the reference voltage of the SDHS is 0.755V.

    The maximum input signal range is 1000mV. That input range also includes the PGA settings before the signal being converted. The PGA can be set from -6.5db to 30.8db.

    Best regards,

    Cash Hao

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