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SA: Report the Switches is ASCII Hex Data format

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.

This command gets the raw hardware states of all switches, returned in ASCII hex format.

The SA: command response includes the physical state of each switch. If you configured the switch to report inverted, that only affects the /N -N or /L -L messages, not this SA: output.



SA:<(Total # of switches / 8) + 1)><SwData0><SwData1>...<SwDataX><CR>

The (Total # of switches / 8) + 1) is essentially the "number of characters of switch data will be coming". The Neuron and Retro Controllers always report 104 switches (which is a value of 0E which is decimal 14, since 104/8 + 1 = 14.) If you want to know how many switches are physically present, you can add up all the switch values from the NN: command.



Documentation Feedback? Requests? Confused?

Hi! I'm Brian, and I'm responsible for the documentation at FAST Pinball. If you have any feedback, requests, corrections, ideas, or any other thoughts about the docs, please let me know!

You can email me at I maintain this site in my spare time, so there might be a week or so delay if you email me.

If you have a more pressing need, reach out to us via Slack, or email Aaron Davis.


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