Perhaps you should try some spelling variations:
"coder precoder _ arduino programming" » "coder precoder _ arduino programmable" (Expand search), "coder precoder _ radio programming" (Expand search), "coder precoder _ learning programming" (Expand search), "coder decoder _ arduino programming" (Expand search)
"spi in python python programming" » "spi in pythons python programming" (Expand search), "spi in piton python programming" (Expand search), "spi in pitons python programming" (Expand search), "spi _ python python programming" (Expand search)

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("coder precoder _ arduino programming") OR ("spi in python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder precoder _ arduino programming\") OR (\"spi in python python programming\"))".
• Removing quotes may allow a broader search: (( coder precoder _ arduino programming ) OR ( spi in python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder precoder _ arduino programming") OR ("spi in python python programming"))*.