avrdude: stk500_getsync(): not in sync: resp=0x00
Arduino 1.5.6-r.2 board is Arduino Pro or Pro Mini
Source is RFBee with TM1637 library referenced to set 4 digit display to 1234 in setup
Seems like there is plenty of room:
Sketch uses 11,698 bytes (38%) of program storage space. Maximum is 30,720 bytes.
Global variables use 592 bytes (28%) of dynamic memory, leaving 1,456 bytes for local variables. Maximum is 2,048 bytes.