- ; g, rck, sck -> low / scl -> high
- cbi PORTB,(1<<0)|(1<<1)|(1<<2)
- sbi PORTB,(1<<3)
+ ; disable hc595 outputs
+ sbi PORTB,0
+
+ ; rck -> low
+ cbi PORTB,1
+
+ ; clear hc595 registers
+ cbi PORTB,3
+
+ ; rck -> high (store shift register data)
+ sbi PORTB,1
+
+ ; enable outputs
+ cbi PORTB,0