This is LED lamp project powered by solar. It will harvesting the Sun during the day and charging the battery. The project uses SEPIC converter that capable of boosting or dropping the input voltage. It allows the use of a battery with a voltage close to the LED conduction voltage. The project is built around ATTiny15L microcontroller.
João Silva, the project designer, said that the software used was straight forward, start the high speed oscillator, start the PWM generator, read voltages, take decisions and increase/decrease PWM output. One note worth mentioning is that the ATTiny85 and the ATTiny15 have two input ports exchanged (Port PB4/PB3 – Pins 2/3) although the ADC inputs are the same.