Atmega328 based Analog sensor

[fl11]

Hi Guys!

In this project, I would like to make an Atmega328 based sensor reader with an OLED display. For the sensor, I need an ADC converter that is an ADS1115. The OLED is a cheap 0.96" i2c display with a breakout board. The power supply is a 3xAAA battery pack with an LDO power regulator.
I designed a 6 pin connector to the board to burn the bootloader and the sketch via an Arduino ISP. The whole setup works fine on my breadboard. So guys here is the schematic. Could you please review it before I start to design the PCB?
Thanks!

p.s.: I would like to run the Atmega at 3.3V and 8mhz.

The modules that I inspired for this project:

https://randomnerdtutorials.com/esp8266-voltage-regulator-lipo-and-li-ion-batteries/
https://learn.adafruit.com/adafruit-4-channel-adc-breakouts/downloads
https://www.arduino.cc/en/uploads/Main/Arduino-Pro-Mini-schematic.pdf

[MarkT]

A decoupling cap on every supply pin - ie Vcc and AVcc both should have one. Layout for
decoupling is important, decoupling cap right next to the pin, good to have groundplane.

For the analog side of the circuitry a separate ground and supply is probably needed for maximum precision and least noise - at the very least keep digital stuff at one end of the PCB,
analog at the other. Separate regulators for analog and digital is standard practice in precision analog circuitry - digital supply rails can be very electrically noisy. Always a linear
regulator for an analog supply unless you've thoroughly tested using a SMPS doesn't
cause issues.

[fl11]

Thanks Mark!