1. the MCU will drive the hc-05 to send a lot cmd ,and the app will
   count how many will it get.
1. after some test ,i think i know ,why sometimes the app get the wrong data
not very clear ,so give me some time to find it.
for example:
	hello world_12345678901**he
1. for now the error rate is about 25~30/50000[25byte]
  and for normal use it is ok.