Atmega328 without Arduino has different LCD prints compared to Atmega328 with Ar

Other Hardware 3rd Party Boards
1

I have a temperature sensor that outputs a certain voltage to the Arduino. I then convert it to analog by using the equation given in the datasheet to output the correct temperature to an LCD screen. When I have my Arduino hooked up, it outputs the exact temperature it is supposed to. When I take the Atmega328 and use it alone from the Arduino, it outputs about 8 degrees off. The temperature sensor itself is still outputting the correct voltage as it's supposed to! But the print is off. I'm using a 5V input to the Atmega328.

I'm using this schematic to use with my Atmega328. Is there anything else I need with this schematic that might affect the analog inputs?

Thank you very much in advance.

7e595144c3e9e0d91b997598a949885c.png
7e595144c3e9e0d91b997598a949885c.png720×528 107 KB

7e595144c3e9e0d91b997598a949885c.png
7e595144c3e9e0d91b997598a949885c.png720×528 107 KB

2

I'm using a 5V input to the Atmega328.

What was the analogue reference voltage on the unnamed Arduino?

How is this an installation issue?

3

I didn’t use the AREF because when I tried, it got a little messy. I might not know how to use it. How do I use the AREF?

I also apologize, I haven’t used the forum before and I thought it fit into installation using the Atmega. I will fix it next time.

4

Also Although possibly outside my area of expertise, it sounds like your power supply is not giving 5V.

5

It turns out it was the AREF pin. I wasn’t aware how to use it, but you just input your analog reference directly into the pin. I wasn’t using it at all so my numbers were thrown off. Thanks your your help!