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ADC10 in msp430g2553

Rushin Thakkar
Expert 1285 points
Other Parts Discussed in Thread: MSP430G2553

i am using MSP430G2553 for converting analog ECG  into digital signal. in my analog hardware there are different stages like instrumentation amplifier,low pass filter,high pass filter, notch filter, dc offset adder circuit. for testing i am using sine wave. output at the end of dc offset circuit look like that

but when i connect this output to p1.1 which is my analog channel 1. in DSO my waveform look like below

when i put 10 uF capacitor before analog channel. shape of wave is better. but amplitude decreases. can you provide me solution?

  • 0
    Guru 92251 points

    Rushin Thakkar said:
    but when i connect this output to p1.1 which is my analog channel 1. in DSO my waveform look like below

    The text on the scope picture is fuzzy, but it looks like the analog signal which is applied to pin P1.1 has a maximum of 8.4V.

    According to the MSP430G2553 data sheet the allowed range of the Analog input voltage is 0 to VCC. Applying an analog voltage greater than VCC will cause the protection diode between the pin and the supply rails to conduct which will clamp the analog input voltage to VCC + diode drop. If the diode current is greater than 2mA the device may be damaged.

    Therefore, your analog hardware needs to limit the input voltage to the range 0 to VCC to avoid this problem of clamping the analog input voltage.

    Also note that the analog input voltage range must be within the selected reference voltage range VR+ to VR– for valid conversion results.

  • 0
    Guru 58965 points

    Read something look like this.

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