Rock/linein

There are Line In from the extension header on rock pro. The latest Rabian has enabled Line in.

1 Tested module

   http://detail.tmall.com/item.htm?spm=a1z10.3-b.w4011-3079905380.27.SocVjO&id=42576261888&rn=b482a0f48f9bab9ef1f5e1ffb433daed&abbucket=7#
   Module power supply pins VCC GND  connect to pro/lite extend port J8  pins 2 1.
   Module audio out pin OUT connect to  pro/lite extend port J8  pins 5/6.

2 Select capture from mic / line in

   echo 1 > /tmp/rk1000_input_sel    #RK1000 capture from mic
   echo 2 > /tmp/rk1000_input_sel    #RK1000 capture from line in

3 test cmd

   capture:
   arecord -D 'default' -V stereo -c 2 -f dat -d 100 out.wav    #100 capture duration