Based on the previous instructions- I made a real gadget, an ATtiny85 ring watch. Today\'s core subject, attiny85. I was advised to use the SOIC version to reduce the watch size and I found the coin battery mAh calculation method to reduce the battery voltage to 2. So this watch needs a low voltage version of the MCU to keep it stable. So I ordered an ATTINY85V-10SU. ( More expensive Any ISP that can program ATtiny85, this time I\'m using Digispark as a small wire. ( I chose CR1220 to fit the size of the ring and I hope it will last more than half a year. ( Reference to previous items) Due to the very limited number of IO pins for ATtiny85, the display and other modules I designed should all run in I2C. Power consumption and power availability are also important factors. I chose an OLED screen drive with ssd1346. It can be found in 4 different sizes, 64x32 is the smallest size. ( Another size is 128x64, 128x32 and 64x48)( Reference to previous items) It should be more stylish if made of wood, but I\'m lazy so just print it out. ( Reference to previous items) A small piece of transparent PET plastic board. It is transparent, provides enough support and is easy to get from many product packaging. Download Arduino 1. 6. 5 (1. 6. 6/7 known compatibility issues- \"Contains outdated recipes. ar. pattern\")ArduinoTiny ( If you are not familiar with GitHub, just click the Download ZIP button) If you install the installation using Windows, it should be: C: \\ Program file \\ ArduinoIf it should be:/app/Arduino if you use OSX. Application/content/JavaOr any path you decompress. In Arduino path, copy the hardware \\ arduino \\ libraries \\ EEPROM. Ħ hardware \\ small \\ avr \\ small folder with very small core. TinyWireM has a known problem, but it hasn\'t been fixed yet, and you can fix it easily: From: to: download the latest source code here You can find more details in the material below: Again, it should be more fashionable if made of wood, but I\'m lazy, so just print it out. Attach Sketchup and STL files for your reference. Reference: step is not a must, but it can make it easy for further welding work and re-programming. Soldering SMD reference: in previous projects I used 2 pins to handle 2 button inputs. This is too expensive for each input button to use the ATtiny85 IO pin. This time I try to handle 3 button inputs using 1 IO pin. Here\'s my setup: Set button-GND -> button -> PIN 2 (PB3, ADC3)up button -GND -> 6. 8k resistor -> button - > Pin 2 Down button-> GND -> 68 k resistance-> button - > Pin 2 various resistance values should be OK and more than 1 k is recommended. 3 buttons have different resistor values, so you can use analogRead () Distinguish the function of which button is pressed. I measured some common resistance simulation values as a reference. You can change the threshold in ATtinyWatch. If different resistors are used, the ino file. e. g. Since the ring watch has a curved surface, it cannot weld all parts on a single PC board. The MCU, OLED, button panel and battery stand are all connected by coated copper wire. VCC and GND coated copper wire should be at 6- 8 cm, and requires the removal of the coating of the intermediate attachment point with sandpaper. The other wires are a little shorter. Here is the connection Summary: ATtiny85: pin 2: button panel pin 4: oled gnd-> Button panel- > Battery stand 5: OLED SDAPin 7: OLED SCLPin 8: oled vcc- > The Battery stand ring is small and cannot be fitted with a normal CR1220 battery stand. So we need some thin heart boards to customize. Made a smaller one. My thin heart plate is renewed Waste cycling from DuPont thread heads and you may find something else near you. Cut a short metal plate into a copper wire and weld it on the copper wire. Bend it and insert it into the loop body, at the positive and negative terminals. Insert the slot in the battery and test the connection. ISP -> ATtiny85MISO-> Pin 6VCC -> Pin 8SCK -> Pin 7MOSI -> Pin 5RESET -> Pin 1GND - > Pin 4 note: If your screen resolution does not exceed 64x32, you can change the resolution defined in ssd1346. he. g. Other programs ATtiny85 reference: When no date time field is selected, the up or down button will go to the debug screen. Value representation: Row 1 (I) : Watchdog timer (WDT) Interrupt count, this value will be reset for each set time operation that exceeds 1 hour interval 2 (M) : Automatic tuning value of Micro Every WDT interrupt per second, the value will be updated for each set time operation that exceeds 1 hour interval 3 (V) : Calibration value of battery power (in millivolts)T) : The original value of the ATtiny85 internal temperature sensor, which is the cumulative value of the last 64 sampled values. Pressing the settings button will toggle the selected date and time field, the selected Press the up and down buttons to change the selected field values. Pressing the set button when the second field is highlighted will complete the set time operation. For each set time operation with an interval of more than 1 hour, Micro The interrupt value per WDT is automatically tuned in seconds. In my experience, keep the voltage and temperature conditions stable, it should not drift more than 1 minute per day after automatic tuning: Pe. g. e. g. Insert the OLED screen into the pit and place all the components in the correct position. Assemble the ring and screw the M2 screw onto the ring body. Other transparent cover references: Time to show everyone what you did!