Qsys error : has write interface but no write control

you have set asi_clk_50, test_pin, camera_clk and sel to avalon_slave_0 which is an altera defined interface for memory mapped components, see:

https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/manual/mnl_avalon_spec.pdf

and as such has to obey the format defined in the document. you have set the signal type to writedata for 4 of the inputs and only 1 writedata is used in an avalon slave interface. hence the warning and a write signal is required with writedata hence your error.

this doesnt look like what you are trying to achieve. perhaps see the avalon conduit interface? also check the interface tab where you can set it all up using the gui