I need to know what is the minimum voltage that a micro-controller can detect

[alfie.max15]

In the project that i am working on i need to detect a signal coming from the mic which is a very weak and in the range of 1mV.

So i need to know can my micro-controller detect that as a high on any port pin...

Or what is the minimum voltage that is required so that the uC can detect and trigger a high in any pin to which it is connected...

Please reply fast if anyone can help...

 

[caesarsrilanka]

In the project that i am working on i need to detect a signal coming from the mic which is a very weak and in the range of 1mV.

So i need to know can my micro-controller detect that as a high on any port pin...

Or what is the minimum voltage that is required so that the uC can detect and trigger a high in any pin to which it is connected...

Please reply fast if anyone can help...

Refer the datasheet of the controller which you are using............

 

[jayanth.devarayanadurga]

I think for 5V MCUs the input high will be from 2.5V to 5V. Refer datasheet. For 3.3V devices it is different.

 

[paulfjujo]

hello,

see microchip with 12bits ADC
so you will get 1mV of resolution
to get deeper resolution use external Adc 16 or 18... bits

 

[alfie.max15]

one doubt...

from the datasheet i got this information

For a supply 2.4v - 5.5v the VIL threshold is < 0.3 * Vcc , VIH > 0.6 *Vcc .

As av example for 5 supply the low threshold is 0.3 * 5v = 1.5v and the High threshold is 0.6 * 5v =3v

what does that mean???

 

[jayanth.devarayanadurga]

It means that low input is fron 0v to 1.5v and high input is from 3v to 5v.

 

[FvM]

A number of microprocessors is equipped with an analog comparator module that can detect mV voltages. Also ADC inputs could be used. But you won't achieve 1 mV accuracy due to offset voltages and limited ADC resolution. An external preamplifier or comparator seems to be a more suitable solution.