org.usfirst.frc.team1736.lib.CoProcessor

Class VisionListener

java.lang.Object

org.usfirst.frc.team1736.lib.CoProcessor.VisionListener

public class VisionListener
extends java.lang.Object

DESCRIPTION:
Full class to set up a UDP listener, look for UDP packets from a vision coprocessor (such as a Beaglebone Black (BBB)), and interpret the json data into target observations. Note that the JSON object structures and the content of the data is tightly tied with the functionality implemented on the coprocessor - this code can likely not be fully understood without looking into that code as well!

USAGE:

1. Instantiate the reciever with the listen address and port.
2. Call the start() method when you are ready to start listening for frames.
3. Once per control loop, call the sampleLatestData() method to load data from the latest frame.
4. During the control loop, call the other getter functions to extract info about this latest frame.

Constructor Summary

Constructors

Constructor and Description
VisionListener(java.lang.String listen_to_addr, int listen_on_port) Constructor for the Vision Coprocessor listener socket.

Method Summary

Modifier and Type	Method and Description
double	getArea(int tgt_idx)
double	getCpuLoad()
double	getFPS()
double	getFrameCounter()
double	getHeight(int tgt_idx)
double	getMemLoad()
double	getNumTargetsObserved()
double	getPacketRxSystemTime()
double	getProcTimeMs()
double	getWidth(int tgt_idx)
double	getX(int tgt_idx)
double	getY(int tgt_idx)
boolean	isCoProcessorAlive()
static void	main(java.lang.String[] args) The main function is used as a test which can be run on a user's PC.
void	sampleLatestData() Locks the most recent data from the coprocessor for use.
void	start() Starts the listener in the background to look for and interpret UDP packets from the coprocessor.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

VisionListener

public VisionListener(java.lang.String listen_to_addr,
                      int listen_on_port)

Constructor for the Vision Coprocessor listener socket. Sets up internal variables to get ready for information to be transmitted from the coprocessor.

Parameters:

listen_to_addr - String of the IP address of the coprocessor (For example, "10.17.36.8")

listen_on_port - integer port number to listen on. Usually between 5800 and 5810 per FMS whitepaper. Must match whatever port the coprocessor is sending information to.

Method Detail

start

public void start()

Starts the listener in the background to look for and interpret UDP packets from the coprocessor.

This method MUST be called after the constructor, but before any attempt is made to use the data from the coprocessor.

sampleLatestData

public void sampleLatestData()

Locks the most recent data from the coprocessor for use. Should be called by controls thread to indicate the control algorithms are ready to start to use a new frame. The information returned by all the other getter methods in this class is based on the data available at the most recent call to this method. Call this method once per control loop, before attempting to use any data from the coprocessor.

isCoProcessorAlive

public boolean isCoProcessorAlive()

Returns:

True if a valid packet has been decoded from the coprocessor recently, false otherwise

getNumTargetsObserved

public double getNumTargetsObserved()

Returns:

Number of targets observed in frame, or -1 if no valid frame available.

getX

public double getX(int tgt_idx)

Parameters:

tgt_idx - The integer index of the target of interest (should be between 0 and getNumTargetsObserved()-1)

Returns:

X coordinate of the specified target observed in frame, or -1 if no target matches provided index.

getY

public double getY(int tgt_idx)

Parameters:

tgt_idx - The integer index of the target of interest (should be between 0 and getNumTargetsObserved()-1)

Returns:

Y coordinate of the specified target observed in frame, or -1 if no target matches provided index.

getArea

public double getArea(int tgt_idx)

Parameters:

tgt_idx - The integer index of the target of interest (should be between 0 and getNumTargetsObserved()-1)

Returns:

Enclosed area of the specified target observed in frame, or -1 if no target matches provided index.

getWidth

public double getWidth(int tgt_idx)

Parameters:

tgt_idx - The integer index of the target of interest (should be between 0 and getNumTargetsObserved()-1)

Returns:

Width of the specified target observed in frame, or -1 if no target matches provided index.

getHeight

public double getHeight(int tgt_idx)

Parameters:

tgt_idx - The integer index of the target of interest (should be between 0 and getNumTargetsObserved()-1)

Returns:

Height of the specified target observed in frame, or -1 if no target matches provided index.

getFPS

public double getFPS()

Returns:

Coprocessor averaged data output rate in Frames per Second

getFrameCounter

public double getFrameCounter()

Returns:

Number of frames processed by the coprocessor so far.

getProcTimeMs

public double getProcTimeMs()

Returns:

Number of milliseconds it took to process the current frame from image down to target data

getCpuLoad

public double getCpuLoad()

Returns:

Percent load of the coprocessor CPU's

getMemLoad

public double getMemLoad()

Returns:

Percent load of the coprocessor's onboard RAM

getPacketRxSystemTime

public double getPacketRxSystemTime()

Returns:

RIO System time when the most recent packet was received.

main

public static void main(java.lang.String[] args)

The main function is used as a test which can be run on a user's PC. It is NOT intended to be called by any part of the robot code!