Module SMCR 

slave mode control register

Modules

ECE

External clock enable

ETF

External trigger filter

ETP

External trigger polarity

ETPS

External trigger prescaler

MSM

Master/Slave mode

OCCS

OCREF clear selection

SMS

Slave mode selection

SMS_3

Slave mode selection - bit 3

TS

Trigger selection

TS_4

Trigger selection