How to detect the negative voltage ?

Dear expert,

I have a need to read the negative voltage . If there are any suggestions.
Please give me ideas .

Can ADC read the negative voltage ?

Very very thanks ~

"Microcontroller Interfacing"
https://www.cq.cx/interface.pl
"Measure a DC Voltage Between -15 V and 15 V"

Regards,
IanP

AVR microcontroller have differential ADC. So you can use them

Bibin John
www.bibinjohn.tk

refer this page
https://en.wikipedia.org/wiki/Analog-to-digital_converter

Added after 5 minutes:

refer
https://www.freepatentsonline.com/5880690.html

The professional method is to use a high impedance op-amp to sample your negative signal, this will protect the original signal from being loaded, then tune the op-amp resistor values to get a positive output with the gain you want so that it will fit the input range of whatever ADC you will use.
Your start circuit is a unity gain op-amp.

If you want a simple solution then use a resistor between Vref of your uC and the input of ADC-IN and another resistor from ADC-IN to actual -ve input.

+-------------------> + Vref
|
\
/
\
/ R1
\
/
|
+------------------> ADC-IN of uC
|
\
/
\ R2
/
\
/
|
+--------------------< -ve ADCInput

Advantages :

1.Very simple

Disadvantages :

1.Ofcourse it needs some more software overhead.
2.Adjust R1 and R2 to your requirement.
3.R1 and R2 very very bigger than input impedance of the -ve ADCInput
4.Too big values of R1 || R2 will reduce the acuracy of ADC.


proton

Hi ,

My idea is you can use opamp as negative amplifer, so that you can direct transfer negative voltage to positive voltage than read out from ADC also no need negative power supply.