What is the name of this old science fiction movie from the 70's?

It was about a man who was a futuristic convict who had a very painful blinking collar around his neck. The man was on a planet (I think was mars) that had thin air but he was able to survive. He lived in a cave and ate these things that grew on plants that looked like sausage. He made a homemade alarm clock by pouring sand through some crafty gadget of his. A UFO looking craft sometimes came searching for him, but he was hidden.