in codeigniter how do i do a join with a where clause

so i have two tables, and i want to get all the rows from table 1 that meet the where clause conditions, and then join them with table two based on the join conditions.

here are the sample tables:

table1:

col1   col2  col3
1      a     val1
2      b     val2
3      c     val3

table2:

col1   col3
1      someval1
2      someval2
3      someval3

now i want to grab all the rows in table 1 where col1 = 2, and join those rows with rows from table2 where table2.col1 = table1.col1. Does that make sense?