Ensure your device works with this simple test.
../examples/mcp3xxx_mcp3008_single_ended_simpletest.py
../examples/mcp3xxx_mcp3004_single_ended_simpletest.py
../examples/mcp3xxx_mcp3002_single_ended_simpletest.py
../examples/mcp3xxx_mcp3008_differential_simpletest.py
../examples/mcp3xxx_mcp3004_differential_simpletest.py
../examples/mcp3xxx_mcp3002_differential_simpletest.py