I added the EAGLE library of my potentiometer, "RK09K1110B1V" by ALPS, from "PCB Part Library" web site.

I had 2 errors on this schematic image.

1st Error - cross section and unintended path at board pattern

2nd Error - unexpected behavior of the analog / degital read without pullup resister.

Reading datasheet of ATtiny3216, I found that the description - "16.3.2.3 Pin Configuration The Pin n Configuration register (PORT.PINnCTRL) is used to configure inverted I/O, pullup, and input sensing of a pin. ~ Pullup of pin n is enabled by writing a ‘1’ to the Pullup Enable bit (PULLUPEN) in PORT.PINnCTRL".

Also, I checked Digital pins of Arduino foundation tutorial that's saying about pinMode(pin, INPUT_PULLUP);. For avoiding complexity in assembling board, I tried to use internal pullup by .ino code (For final project, I want to use arduino code (not C language code) for my input/output board for using Adafruit NeoPixel library that supports .ino code. )

Then I made an experiment testing electronics using ATtiny3216 breakout board and bread board with these senseors.

At first, it looks the outcome of sensor values (especially the values of analogRead() from potentiometers) are not stable.

After added 0kΩ pullup resisters to switches, the values look to be stable.

Then I refined the schematic diagram in terms of

1. 1) Workaround routing against 0kΩ resister
2. 2) Added 10kΩ pullup resister to switch

Schematic pattern (with pullup resister )

3216inputboard_size_min_16mil.sch

Input Board pattern for final project (as of April 2020) (with pullup resister )

3216inputboard_size_min_16mil.brd

Actually, it's not completed as of 21 APril - I need to setup the minimum path size for 16 mil in DRC rule. I will update this altogether when I will add the output of NeoPixel to the same board (as input-output board of my final project) .

My first idea is writing .ino code to ATtiny3216 board and connecting breakout board pins to potentiometer and audio output jack.

However, it's difficult to write ".ino" code including Mozzi library to ATtiny3216. It seems because there is no compatibility in Mozzi library in Attiny 3216 at least default configuration. So I moved to 2nd idea - embedding the program (with Mozzi) to Arduino Uno.

Connection (Arduino UNO - breadboard

• VCC - VCC for potentiometer x 2
• GNC - GND for potentiometer x 2 and Audiojack
• Analog 0 pin - Potentiometer 1(stepGain)
• Analog 1 pin - Potentiometer 2(interval)
• Digital 9 pin(*) - TIP of Audio Jack

(*)Arduino Digital 9 pin is reserved for audio output by Mozzi library.

Connection to audio system

Serial monitor example when I counter-clockwise rotated potentiometer 2(interval) - parallel circuit of resister

Parallel circuit of 2 potentiometers.

Serial monitor example when I counter-clockwise rotated potentiometer 2(interval) - serial circuit of resister

Serial circuit of 2 potentiometers.

1. Checked the cable spec

I checked a datasheet of TTL-232R Cable (TTL-232R-5V)

2. Connect the cable and ESP32-CAM

    USB-TTL           ESP32-CAM
    TXD ( Orange )    UOR
    RXD ( Yellow )    UOT
                    ( IO0 - GND )
    5V (Red)          5V
    GND (Black)       GND

When writing a program to ESP-32, short the IO0 pin and GND pin. (As I did not have female-female cable or pin, I used two male-female jumper cables and breadboard).

3. Setup the board on Arduino IDE

• Board: ESP32 Wrover Module
• Partition Scheme: Huge App(3MB No OTA)
• Flash Mode: QIO
• Flash Frequecy: 80MHz
• Upload Speed: 921600

4. Write the program

On Arduinoi IDE,
File > Sketch Examples > ESP32 > Camera Web Server

• Change the SSID and WiFi passowrd on that.
• Change the comment out definition of camera model and activate #define CAMERA_MODEL_AI_THINKER
• Write a program from Arduino IDE.

5. Start ESP32-Cam

1) Plug-off the short jumper between IO0 and GND

2) Push “RESET” button on ESP32-Cam

I had errors on WiFi connection in my home Wifi router. It might be caused by specification in WiFi or that security spec.

At a datasheet of ESP32-cam by AI Thinker, Wifi Specification is 802.11 b/g/n. My home wifi router might automatically connect to higher specification than that. After I changed the Wifi SSID and password to the one of tethering network provided by my smartphone, that worked.