to me it made sense that EN_AA settings are controlling the receiving pipes if an ACK has to be sent back upon receiving a valid packet.
then i thought that the settings in SETUP_RETR are telling the transmitter if it should wait for an ACK at all.
but then it started to look like the EN_AA also influences the transmitter.
when using e.g. ENAA_P0=1 and sending to a receiver with ENAA_P0=0 it does not work.
thanks for checking. thomas