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AP-8 Serial Protocol
The AP-8 serial connection conforms to the Parallax AppMod bi-directional communications protocol, which
operates at TTL (0 to 5 VDC) using “open-true” baud mode to enable daisy-chaining devices. All exchanges are
initiated by the host controller. The format of host communications to the AP-8 is as follows:
"!AP8", address, command { , data }
… where “!AP8” is the preamble that allows the AP-8 to exist on the same communications line as other devices
(e.g., DC-16, RC-4), address is the board address set with jumpers on ID0 and ID1, command is a single
character command designator, and data is any value that may be required by command. The following section
details valid commands (“V”, “G”, “P”, and “X”) for the AP-8.
“V” – Get AP-8 Version number
Syntax: “!AP8”, address, “V”
Reply: 3-byte (ASCII) version string
Prop-1 Example:
SEROUT Sio, OT2400, ("!AP8", %11, "V")
SERIN Sio, OT2400, id0, id1, id2
DEBUG "AP-8 Version ", #@id0, #@id1, #@id2, CR
“G” – Get AP-8 Status
Syntax: “!AP8”, address, “G”
Reply: Single byte that indicates the AP-8 status and switch settings. See below.
Bit When 1 When 0
7 AP-8 is Playing AP-8 is Idle
6Reserved Reserved
5 Single-shot play Loop play
4 Record mode selected Play mode selected
3Reserved Reserved
2 Segment switch 2 is Open Segment switch 2 is Closed
1 Segment switch 1 is Open Segment switch 1 is Closed
0 Segment switch 0 is Open Segment switch 0 is Closed
Prop-1 Example:
Main:
SEROUT Sio, OT2400, ("!AP8", %11, "G")
SERIN Sio, OT2400, ap8Status
In this example, ap8Status will hold the current state of the AP-8. See the example program for reading and
decoding the status bits.
