After using raspi-config to disable OS control of serial port and running ‘mavproxy.py --master=/dev/ttyAMA0 --baudrate 57600 --aircraft MyCopter’ error displayed ttyAMA0 did not exist. Checked /dev and could not locate ttyAMA0.
After research I found the link: https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=148515 - ‘Serial port missing - latest Jessie after update/upgrade’ dated 17th May 2016.
If you come across this problem the solution is as follows:
'sudo nano /boot/config.text’
change ‘enable_uart=1’ to ‘0’ and reboot.
I have tried this and it works