The Christmas LED-Snowflate-thermometer
This LED "Snowflate" made from mainly blue and white LEDs and can serve as Christmas present, Christmas ornament or night light. The device also has a thermometer. Snowflake has 6 beams and every beam contains 8 superbright LEDs. I have used blue and white LEDs with different diameters. Their location is shown in the figure
The assembled snowflake looks as follows:
The circuit of the device is shown in the figure below. 48 LEDs and 7-segment indicators are connected to the pins of the microcontroller ATMega8535.
LEDs are divided into 6 "beams" (common-anode) to 8 pieces each. LED cathodes are connected to pins HK1 - HK8, and anodes - to pins HA1 - HA6. Cathodes and anodes of a three-digit seven-segment LED (with common anode) are connected to pins LK1 - LK8 and LA1 - LA3 respectively. Transistors VT1 - power transistors with VT8 - npn (!). I used KT815. I haven't found npn transistors in an appropriated package in the Eagle library and used pnp transistors on the circuit.
As themperature sensor I have used IC3 DS18B20, the button S1 is reserved and doesn't used by current version of firmware. The UART-s pin and pin PD4 used for the bootloader. I have used the crystal resonator with frequency 11.0592 MHz.
Assembled device:
Video demonstration
Download:
Firmware (11.0592 MHz)
Source code
Circuit adn PCB, Eagle
LED board, SprintLayout
