uses a 3-bit counter to drive PWM on 8 output channels. Each channel is controlled by a dedicated 3-bit register that specifies its PWM level: 0 means always off, 1 is for 1/7 on, 5 is for 5/7 on and 7 is 7/7 (always on)
How to test
after reset, all output pins will be low. Use set, addr and level pins to set PWM level=level0+2level1+4level2 on channel=addr0+2addr1+4addr2. The corresponding pin will start oscillating between 0 and 1 according to the clock and the set level.