This might be caused by a corrupted firmware on the telemetry radio. Re-install the firmware, as described in the next procedure:
Using mission planner:
- Connect the telemetry radio to the computer, select the serial port and 57600 bauds, don't hit connect yet.
- Go to Initial setup >optional hardware >3DR Radio.
- Click upload firmware (local).
APM planner doesn't have an upload firmware option, but MAC users can try the next procedure in a terminal:
- wget http://firmware.diydrones.com/SiK/stable/radio~hm_trp.ihx
- wget http://smaccmpilot.org/artifacts/sik_uploader.py
- sudo easy_install pexpect
- python sik_uploader.py --port ENTER_SERIAL_PORT_HERE(i.e. /dev/cu.usbserial-DN0019TF) --baudrate 57600 radio~hm_trp.ihx
If the firmware upload doesn't correct the problem then the telemetry radio is damaged or defective.