An example setup of a picam with nerves served over http using vintagenetwifi, the end result of this medium article.
Clone and run these commands to burn the firmware to a sdcard
mix deps.get
mix firmware
mix burn
Boot up your raspberry pi with this sdcard inserted, and connect to the wifi access point
SSID: v_net
PSK: ex.vnet.wifi
The camera feed is served over the endpoint 192.168.0.1:4001.