Measure upto +-40V using MCU

[Vindhyachal.takniki]

1. I have to make a multimeter (very low cost basic) , measuring 0V-40V & in reverse also.
2. I have a ckt which is attached.
3. MCU is powered by +5V , 10 bit adc.
4. First I have level shifted the signal to +2.5V i.e mid supply. Then 40V is divided into 2V.
So that max signal can swing 0.5 to 4.5V at adc input of MCU.
5. Any comments/suggestions on it?
6. In simulation it works fine.
7. Also I have added two back to back diode for protection in case of overvoltage.