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Instrument for measuring DSP pin signal

Anonymous
Anonymous

Hi,

 

I would like to ask one question on voltage/signal measurement.

 

For two types of measuring devices

 

Signal, GPIO voltage

Power / GND voltage

Oscilloscope

Yes

Yes

Multi-meter (digital, with protection mechanism)

Yes ?

Yes ?

Multi-meter (analog)

?

?

 

Someone told me that analog multi-meter cannot be used to measure DSP signal directly because its internal reverse emf ε could damage the DSP chip. Is it true? I also heard that in contrast to analog multi-meter, digital multi-meter could measure DSP pin signals. What is the protection mechanism in it?

 

 

 

 

Thanks,

Zheng

  • 0
    TI__Expert 5475 points

    Hi,

    Specialy the old Analog meters ususally uses lower resistance within the unit and they tend to generate high current which has the potential of damaging the device.

    Best regards, Zegeye

  • 0 in reply to Zegeye Alemu
    TI__Intellectual 1670 points

    This is true, but to clarify, all multimeters use the same type of circuit for measuring resistance.  They have a battery voltage source, a metering circuit, and resistances that switch based on what range you want to measure (although some digital meters don't switch this value). 

    Digital meters, being generally newer, use much lower current and open circuit voltage to measure resistance.  Some older analog meters had a 9V battery that was used as a voltage source.  This voltage has the potential to damage I/Os, although the likelihood is low since the current on quality analog meters is usually very low.

    When measuring voltage, analog meters do have a higher internal inductance (due to the magnetic meter winding, which is an inductor), which could potentially spike a higher voltage back on test leads when starting to disconnect, or when a digital I/O is switched low.

    These two reasons are why we don't recommend analog meters for digital circuits.

  • Anonymous
    0 Anonymous in reply to KevenC

    Dear Keven,

    I will use digital meter for DSP chips. Thanks very much for the detailed answer.

     

    Zheng