Compact speedometer with OLED display and temperature measurement.
It features an ATtiny85 uC with USB programming and battery charging and protection circuitry. I will be using it to measure the speed of my bicycle and determine the temperature around me on my rides.
The project consists of 2 pcbs: the sensor that will be mounted on the wheel of my bike and the actual speedometer.
Card based to ESP32 Wroom 32D
Micro USB Interface Power & Serial
2.2 Inch ( 240x230 ) Color LCD Screen
Micro SD Card Reader ( SPI )
3.7v LiPo Battery Port
Real Time Clock ( I2C )
Selection button x 4 ( I2C over I2C GPIO Extender)
External Reset Port ( SWITCH )
External Analogic Input X 2
External Optocoupled Digital Input X 4
External Optocoupled Digital Output X 4
External I2c Port...
LED driver for single lipo/lion cell with step up (5-28V, 1A) constant current (0.6A, 225mW dissipation) regulator, TP4056 charger (20-1000mA), over-/undervoltage protection (2.5V-4.3V) and a microcontroller.
The circuit output is 7-9.2V (R6+R11/R7) for 3 high power LEDs in series, constant current 30-35mA (R8). P9 needs to be connected to B+ (on) or GND (off). It can also be used to dim the LEDs...