How to send commands
Devices answer and/or react to commands if:
- they understand the command. Many devices do not support all commands they should according to the spec. Kwikwai is a good tool to test.
- the command was sent using the proper addressing mode. The HDMI specification, as well as CEC-O-MATIC, indicates for each command if it must be broadcast or directly addressed.
- they "recognize" the sender (or the "initiator"). This may vary from command to command for the same device. Generally, commands sent by an existing device on the bus (one that asks messages to it) are OK, but sometimes commands are also recognized when coming from F or a random device. There is no rule here and again, kwikwai is a good tool to test.