This is small project for testing Attiny13a with Arduino IDE.
It made is for testing tiny's pwm capability.
Attiny13a has 2 pwm pins, pwm0 and pwm1 as shown:
ATMEL ATTINY13 / ARDUINO
+-\/-+
Ain0 (D 5) PB5 1| |8 Vcc Ain3 (D 3) PB3 2| |7 PB2 (D 2) Ain1 Ain2 (D 4) PB4 3| |6 PB1 (D 1) pwm1 GND 4| |5 PB0 (D 0) pwm0 +----+
Fritzing project with schematic, breadboard and pcb can be found at: