How do I add entities manually on configuration.yaml for MQTT integration?

I have Home Assistant installed on the RPI4 and I have integrated multiple devices via tuya cloud and sonoff LAN. I also configured some ESPs by ESPhome and everything works perfectly. Now I have a project with arduino mega that was already running even before having HA, I configured the sketch to communicate with mqtt and it connects. I even tested it with mqtt explore, both arduino mega and mqtt in home assistant send messages to mqtt Explore. Also when I send commands from the mqtt topic the arduino receives and performs the command actions. The problem is that mqtt doesn’t add the entities. I don’t know if you can help me overcome this barrier. Thanksfrom Mozambique.

Unless they are programmed to send discovery packets, you will need to add them manually using the configuration.yaml file:

Yep, you either implement discovery, or you have to configure manually via yaml.

Thank you so much. i managed to fix my issues using this tutorial:

Thank you so much. i managed to fix my issues using the tutorial bellow: