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AV: Set Main Left/Right Speaker Volume

FAST Serial Protocol: Overview & First Steps

This documentation section is about the FAST Serial Protocol (FSP) commands, which are the low-level commands a host computer sends to a FAST board. Most FAST Pinball makers do not need to know about these details, since the pinball game framework (such as the Mission Pinball Framework) handles this communication for you.

If you're writing your own game framework, we have a series of programming guides. Also, be sure to read the overview of how FSP works and how to connect first.

Coming soon!

This section of the documentation is not yet complete and will be coming soon. However, if you need this now, and/or you want to share what documentation is most important to you, please post to the #docs channel in the FAST Pinball Slack community. Thanks!

The AV: command is used to set the main left/right speaker volume of the FAST Audio Interface Board. The volume level is a value between 0x00 and 0x3f (decimal 0-63). The mode of the audio system can affect the speaker behavior. See the AM: command for details. Depending on the mode set, the speakers can be disabled or do automatic crossfade when the headphones are plugged in.

Command Syntax


Data is a a volume value from 00 to 3F (0-63)

The return value is the same as what was passed in.

The command AV:18<CR> will return AV:18<CR>, confirming the speaker volume was set to 18 hex, which is 24 decimal, or about 38% volume (24/63).

If the mode of the headphone is set to AUDIO_HEADPHONE_MODE_DUCK (see AM: command) the left/right volume channel will increase or decrease over time based on the new settings.

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