Server Information Packets

ActivMedia Robotics

Like its PSOS and P2OS predecessors, AROS automatically and repeatedly sends a packet of information over its HOST serial port to a connected client. The standard AROS SIP informs the client about a number of operating states and readings, using the order and data types described in the nearby Table.

Table 3. Standard Server Information Packet

NAME

VALUE

DESCRIPTION

HEADER	int	Exactly 0xFA, 0xFB
BYTE COUNT	byte	Number of data bytes + 2 (checksum), not including header or
		byte-count bytes
STATUS/PACKET	0x3S =	Motors status

TYPE	2	Motors stopped
	3	Robot moving
XPOS	int	Wheel-encoder integrated coordinates; platform-dependent units;
		multiply by DistConvFactor‡
YPOS	int	to convert to millimeters.
THPOS	sint╪	Orientation in platform-dependent units—multiply by
		AngleConvFactor‡ for degrees.
L VEL	sint	Wheel velocities in mm/sec (VelConvFactor‡ = 1.0)
R VEL	sint

BATTERY	byte	Battery charge in tenths of volts (101 = 10.1 volts, for example)
STALL AND	int	Motor stall and bumper indicators. Bit 0 is the left wheel stall
BUMPERS		indicator, set to 1 if stalled. Bits 1-7 correspond to the first bumper
		I/O digital input states (accessory dependent). Bit 8 is the right
		wheel stall, and bits 9-15 correspond the second bumper I/O
		states, also accessory and application dependent.
CONTROL	sint	Setpoint of the server’s angular position servo—multiply by
		AngleConvFactor‡ for degrees
FLAGS	sint	Bit 0 motors status; bits 1-4 sonar array status; bits 5,6 M-STOP;
		bits 7,8 ledge-sense IRs; bit 9 joystick button; bit 10 auto—
		charger power-good.
COMPASS	byte	Electronic compass accessory heading in 2-degree units
SONAR COUNT	byte	Number of new sonar readings included in SIP
NUMBER	byte	If Sonar Count>0, is sonar disc number 0-31; reading follows
RANGE	int	Sonar range value; multiply by RangeConvFactor‡
…REST OF THE SONAR READINGS…

GRIP_STATE	byte	Gripper state byte.
ANPORT	byte	Selected analog port number 1-5
ANALOG	byte	User Analog input (0-255=0-5 VDC) reading on selected port
DIGIN	byte	Byte-encoded User I/O digital input

DIGOUT	byte	Byte-endcoded User I/O digital output
CHECKSUM	integer	Packet-integrity checksum

‡Client-side data-conversion factor. Consult the ARIA parameter file your robot. ╪ Explicitly, a signed integer.

AROS also supports several additional SIP types. These include an “alternative” SIP that currently is not supported by Saphira or ARIA.15 See following sections in this chapter for a description of the extended SIP types.

15Indeed, if enabled, the alternative SIP apparently will “break” the client software. Read carefully.

ActivMedia Robotics

SERVER INFORMATION PACKETS

multiply by DistConvFactor‡

AngleConvFactor‡ for degrees.