The envelope can take the shapes shown below according to combinations of the
CONT, ATT, ALT and HOLD signals.
B3 B2 B1 B0
CONT ATT ALT HOLD
0 0 x x \
\---------------------
0 1 x x /|
/ |--------------------
1 0 0 0 \ |\ |\ |\ |\ |\ |\ |\
\| \| \| \| \| \| \| \
1 0 0 1 \
\---------------------
1 0 1 0 \ /\ /\ /\ /\ /\ /
\/ \/ \/ \/ \/ \/
1 0 1 1 \ |--------------------
\|
1 1 0 0 /| /| /| /| /| /| /| /
/ |/ |/ |/ |/ |/ |/ |/
1 1 0 1 /---------------------
/
1 1 1 0 /\ /\ /\ /\ /\ /\
/ \/ \/ \/ \/ \/ \
1 1 1 1 /|
/ |--------------------
NOTE - The writing to register RD will reset the envelope frequency clock
Version: v005
24
Date: 22.05.2012