oDCMotor2 Object

The oDCMotor2 Object uses three digital I/O lines to communicate with an H-Bridge circuit which handles the voltage and current requirements of the DC Motor it is connected to.  The H-Bridge that the oDCMotor2 Object is designed to work with has 2 drive inputs that have a shared enable line.  The L293 and L298 H-Bridges are configured in this way.  An optional I/O line controls a mechanical braking device. 

The oDCMotor2 Object is capable of driving a DC Motor at 255 different speeds, in forward or reverse plus free spinning, active braking, and friction braking modes.  The speed at which the motor spins is specified by a single signed value which has a range of -128 to +127.  This signed value also specifies the direction that the motor turns.  When this value is 0, the motor is at free-spinning rest.  When the value is a positive number from 1 to 127, the motor turns forward at the speed indicated by the value.   When the value is a negative number from -1 to -128, the motor turns backwards at the speed indicated by the value. 

The physical direction that the motor will turn can be set to:  forward turns clockwise and reverse turns counter-clockwise  or  forward turns counter-clockwise and reverse turns clockwise.

A brake property can be used to apply brakes which when set, the speed value is ignored and the motor will quickly stop. 

When the oDCMotor2 object is initialized, it configures the oHBridgeH object to use the L293D H-Bridge by setting the oHBridgeH object's properties. It then sets the oDCMotor2 object's properties as specified in the arguments to the Init method.

The Speed property controls the speed of the motor.  When operating, a 0 in the Speed property will cause the motor to be at a full stop. If the Speed property is greater than 0, then the DC Motor will go forward at a speed specified by the Speed property. The higher the number (up to 127), the faster the motor will turn. If the Speed property is less than 0, then the DC Motor will go backwards at a speed specified by the Speed property. The lower the number (down to negative 128), the faster the motor will turn in reverse.

The actual direction that the DC Motor spins when going in the "forward" direction can be reversed by setting the Invert property.

When the Brake property is set to 1, the L293D H-Bridge is set in such a way that the motor to generate power back into itself, effectively driving itself back the other way which causes it to come to an abrupt stop without the need for mechanical braking.

The Operate property specifies if the motor is on or off.  When the Operate property is set to 1 the L293D H-Bridge is set to drive the motor. When the Operate property is set to 0 the L293D H-Bridge is reconfigured and the motor stops.

The HBridge property is an instance of the oHBridgeH object which is created when the oDCMotor2 object is.  The oDCMotor2 object configures the oHBridgeH object in such a way that it will provide the proper I/O control of the L293D H-Bridge that is connected to the DC Motor.  Attributes of the motor's operation can be adjusted by directly manipulating the oHBridgeH object. Note that doing so may change the way the motor behaves to something different than the way described in this document.  (see oHBridgeH object for more detail)

The maximum number of oDCMotor objects that can be dimensioned in a single application program is 2, limited only be the number of PWM channels available in the ooPIC.

The following table lists the properties of the oDCMotor2 Object:

Property	Description
Speed	A value that specifies how fast and in what direction the motor turns. Object Class:  oPower   Value Range: -128 to +127 Data Type:  Numeric   Default Value:  0 When operating, a 0 in the Speed property will cause the motor to be at a full stop. When the Speed property is greater than 0, the motor will go forward at a speed specified by the magnitude of the Speed property. The higher the number (up to 127), the faster the motor will turn. If the Speed property is less than 0, then the motor to go backwards at a speed specified by the magnitude of the Speed property. The lower the number (down to negative 128), the faster the motor will turn in reverse. Speed Description -128 Full Reverse -96   -64 Half Reverse -32   0 Stopped 32   64 Half Forward 96   127 Full Forward The Speed property is an oPower object which has properties and methods such as SetFullForward and Stop that can also be used to control the speed of the motor.  Examples:  A.Speed =  64  A.Speed.SetFullForward A.Speed.Stop A.Speed++ A.Speed.Value.Dec
IOLineP	A value that specifies which PWM I/O Line is connected to the motor driver's Enable line. Object Class:  oIOLineP   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 IOLineP Description 0 The PWM signal is outputted on I/O Line 18.  18 can be assigned to IOLineP in place of 0 but it will read back as 0. 1 The PWM signal is outputted on I/O Line 17.  17 can be assigned to IOLineP in place of 1 but it will read back as 1.
IOLine1	A value that specifies which I/O Line is connected to the motor driver's first drive line. Object Class:  oIOLine   Value Range:  0 - 31 Data Type:  Numeric   Default Value:  0 Some I/O Lines have special purposes.  Be sure to see oIOLine help file for details.
IOLine2	A value that specifies which I/O Line is connected to the motor driver's second drive line. Object Class:  oIOLine   Value Range:  0 - 31 Data Type:  Numeric   Default Value:  0 Some I/O Lines have special purposes.  Be sure to see oIOLine help file for details.
Invert	A value that selects if the physical direction the motor turns is inverted. Object Class:  oSelect0to1L   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 Invert Description 0 Motor turns in the direction specified by the Speed property. 1 Motor turns in the direction opposite the one specified by the Speed property.
Brake	A value that selects if the brake is on or off. Object Class:  oSelect0to1L   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 When the Brake property is set to 1, the I/O lines specified by the IOLineA and IOLineB properties are set to 0 volts and IOLineP is set to 5 Volts.  Setting the Brake property will cause the motor to generate power back into itself, effectively driving the it back the other way which causes it to come to an abrupt stop without the need for mechanical braking. Brake Brake Output 0 Brakes are off. 1 Brakes are on.
Operate	A value that selects if the motor is on or off. Object Class:  oOperate   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 Operate Constant Description 0 cvOff The motor is off. 1 cvOn The motor is on.
Direction	A value that indicates the direction that the motor is turning. Object Class:  oLogic   Value Range:  0 - 1 Data Type:  Numeric   Default Value:  0 The Direction property will be set or cleared depending on if the Speed property is negative or not.
HBridge	The I/O function object used to control the Motor Driver. Object Class:  oHBridgeH   Value Range:   Data Type:  Numeric   Default Value:  0 When the oDCMotor2 object is created, it configures its oHBridgeH object to use L293D H-Bridge by setting its properties to: HBridge.PWM.Period = 254 HBridge.Mode = 1 HBridge.Option = 1 Attributes of the motor's operation can be adjusted by directly manipulating the oHBridgeH object, but note that doing so may change the way the motor behaves to something different than the way described in this document.
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

' This program ramps a DC Motor's speed ' up and down / forwards and backwards. Dim A As New oDCMotor2 Sub Main() A.IOLineP = 17 A.IOLine1 = 27 A.IOLine2 = 25 A.Operate = 1 A.Brake = cvOff Do For A = -100 To 100 ooPIC.Delay = 2 Next A For A = 100 To -100 step -1 ooPIC.Delay = 2 Next A Loop End Sub

Caution: Do NOT connect the outputs of the ooPIC directly to a DC Motor. The TTL circuitry of the ooPIC is not designed to drive the power requirements of a DC Motor.  Doing so can potentially damage the ooPIC's TTL outputs.

L293D H-Bridge Driver and DC Motor.
L293D Pin Name Description First set I/O Name Second set I/O Name ooPIC I/O Line 1 Enable 1 Output Enable for Outputs 1 and 2 IOLineP   17 or 18 2 Input 1 Control Line for Output 1 IOLine1   Any* 3 Output 1 Output 1       4 Gnd Gnd Gnd   Gnd 5 Gnd Gnd Gnd   Gnd 6 Output 2 Output 2       7 Input 2 Control Line for Output 2 IOLine2   Any* 8 Vs Supply Voltage of up to 36       9 Enable 2 Output Enable for Outputs 3 and 4   IOLineP 17 or 18 10 Input 3 Control Line for Output 3   IOLine1 Any* 11 Output 3 Output 3       12 Gnd Gnd   Gnd Gnd 13 Gnd Gnd   Gnd Gnd 14 Output 4 Output 4       15 Input 4 Control Line for Output 4   IOLine2 Any* 16 Vss Logic Supply Voltage volts

*Caution: I/O lines 16 through 23 are used for special purposes.  Be sure not to specify any of these I/O lines if these special functions are in use.

Bugs: No known bugs.