requires 5.10 for named capture groups:

This code will even give you the sequence.

use v5.10;
use strict;
use warnings;

my $str = "AB ABDA DCACCB AAA BSAA CAAB ACS ABA DBA BA DASSABACA A";


while ( $str =~ / (?<_1> BA[ABC]{2} ) | (?<_2> CA[CD]{2} ) | (?<_3> DA
+[SC]{2} ) /gx) {
    print keys %+, " => ", values %+, " at pos ", pos($str), " \n";
}
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_2 => CACC at pos 13 
_3 => DASS at pos 48 
_1 => BACA at pos 53
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edit

inserted /x for readability

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