oJoyStick Object

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Description
Operation
Properties

Examples
Related
Version History & Bug list

Description:

A Hardware Object that reads an Atari style joystick and returns an URCP heading value.

The following table lists the size and availability of the oJoyStick Object.

	Object	Size	Description	A1	A2	B1	B2	C1
	oJoyStick	4 Bytes	Reads an Atari style joystick			x	x	x

Operation:

The oJoystick Object monitors a joystick which is expected to be an array of 4 switches. The 4 switches are arranged where one switch is pressed for any one of the 4 directions N, E, S, W that the joystick is pressed and two of the switches are pressed if the joystick is pressed in one of the 4 directions NE, SE, NW, SW. Joysticks made for the Atari game systems and computers provide this type of 4-bit value. A vintage Atari joystick is constructed in the way.

When the joystick is pressed in any of the 8 possible directions, the Pressed property is set to 1, otherwise the Pressed property is cleared to 0.

When created, the oJoystick Object also creates an instance of the oOrbitSwitch4 object which it uses to read the 4 I/O lines and generate the Heading value. Modifying any of the properties of the oOrbtSwitch4X Object instance will affect the oJoystick Object's operation. See the oOrbitSwitch4 for more detail on how the 4 I/O lines are read.

Properties:

The following table lists the properties of the oJoyStick Object:

Property
Description

Heading

A value that indicates the current direction the joystick is being pressed.

Object Class: oHeading Value Range: -128 to +127

Data Type: Numeric Default Value: 0

I/O Inputs Position Heading Pressed

URCP Heading

0001 Front 0 1

0011 32 1

0010 Left 64 1

0110 96 1

0100 Back -128 1

1100 -96 1

1000 Right -64 1

1001 -32 1

Other Unchanged 0

Pressed

A value that indicates if the joystick is being pushed to one side.

Object Class: oLogic Value Range: 0 - 1

Data Type: Numeric Default Value: 0

IOPack

A value that specifies which pack of 4 I/O lines is connected to the Joystick.

Object Class: oIOPack Value Range: 0 - 7

Data Type: Numeric Default Value: 0

Some I/O Lines have special purposes. Be sure to see oIOPack help file for details.

Operate

A value that selects whether or not the joystick is read.

Object Class: oOperate Value Range: 0 - 1

Data Type: Numeric Default Value: 0

Operate Constant Description

0 cvOff The joystick is not read.

1 cvOn The joystick is read.

DIO

The I/O function object used to read the joystick.

Object Class: oOrbitSwitch4 Value Range: -128 to +127

Data Type: Numeric Default Value: 0

Address

Returns a pointer to the address of the oCounter Object instance.

Object Class: oAddress Value Range: 0 - 127

Data Type: Pointer (Read Only) Default Value: Address of Object

Examples:

In the following example, the oJoystick Object is used.

'This program reads an Atari style 
'joystick and outputs the URCP 
'value to I/O lines 8 - 15.

Dim J As New oJoyStick
Dim D As New oDIO1(7,cvOutput)
Dim C As New oDIO8(3,cvOutput)

Sub Main()
  ooPIC.PullUp = cvTrue

  J.IOPack = 5
  J.Operate = 1
  Do
    C = J.Heading
    D = J.Pressed 
  Loop

End Sub

Connections:

The joystick itself consisted of five switches which are arranged where four of them are used for the directions (UP, DOWN, LEFT, RIGHT) and one is for fire button. The joystick connector is a 9 pin D-shell connector. Normally all switches are open, when he joystick is pressed from the center position, one or two position switches are closed (according to what direction the stick is pressed). The fire button worked so that it closes when the button is pressed. All of the switches are connected between ground and corresponding signal pin of the joystick connector.

9 pin D-SUB female connector layout

Pin	Color	Description
1	WHT	Up
2	BLU	Down
3	GRN	Left
4	BRN	Right
5	n/c	Not connected
6	ORG	Button
7	n/c	Not connected
8	BLK	Ground(-)
9	n/c	Not connected