oPWMH Object

Description
Operation
Properties

Examples
Related
Version History & Bug list

An Object that provides a high-speed Pulse-Width-Modulated output using hardware specific I/O lines.

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

Object Size Description A1 A2 B1 B2 C1

oPWMH 3 Byte An Object that controls the PIC's oPWMH Hardware Module. x x x x x

Operation:

An oPWMH Object outputs a Pulse-Width-Modulated clock cycle on the I/O line specified by the IOLine property.

The output clock cycles at a frequency 19.6khz. The Pulse-Width of the logic-high portion of the clock cycle output is determined by the value of the DutyCycle property which is expressed as ratio of an 8-Bit number where 127 would be 50%

The Operate property specifies if the logic-high portion of the clock cycle output is generated. When the Operate property is set to 1, the PIC's PWM Module starts generating PWM pulses. When the Operate property is set to 0, the PWM pulses are discontinued and the specified I/O Line is set to 0-Volts.

The oPWMH Object uses an instance of the oPWM object which it uses to generate the Pulse-Width-Modulated output. Note that all other objects that use the oPWM object will share the PIC's PWM Hardware. Most properties of the oPWM instance can be adjusted and will affect the oPWMH object's operation such as PWM.PreScale which is used to specify the frequency of the output clock cycle. (see oPWM Object for more detail)

Properties:

The following table lists the properties of the oPWMH Object:

Property
Description

DutyCycle

A value that specifies the duty cycle of the PWM output.

Object Class: oByte Value Range: 0 - 255

Data Type: Numeric Default Value: 0

This is the count at which the PWM output switches state to 0.

DutyCycle Operate Pulse Width Output

Any 0 0

0 Any 0

63 1 25%

127 1 50%

191 1 75%

255 1 100%

IOLine

A value that specifies which PWM I/O Line is used to output the PWM.

Object Class: oIOLineP Value Range: 0 - 1

Data Type: Numeric Default Value: 0 (18)

IOLine Description

0
The PWM signal is output on IOLine 18. 18 can be assigned to the IOLine in place of 0 but it will read back as 0.

1
The PWM signal is output on IOLine 17. 17 can be assigned to the IOLine in place of 1 but it will read back as 1.

Operate

A value that selects whether or not the PWM is outputted.

Object Class: oOperate Value Range: 0 - 1

Data Type: Numeric Default Value: 0

Operate Constant Description

0 cvOff
The PWM signal remains Low.

1 cvOn
The PWM signal outputs a high pulse with a Duty Cycle determined by the DutyCycle property and the Period property.

PWM

The PIC Hardware object used to output the PWM signal.

Object Class: oPWM Value Range: 0 - 256

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

Example:

In the following example, the oPWMH Object is used.

Visual Basic Syntax

C and Java Syntax

'This program causes 
' I/O Line 17 To 
' output a PWM signal.
' with a Duty Cycle
' that changes.

Dim A As New oPWMH

Sub Main()
  A.IOLine = 17
  A.Operate = 1
  Do
    A.DutyCycle.Inc
    Delay = 10
  Loop
End Sub

//This program causes 
// I/O Line 17 To 
// output a PWM signal.
// with a Duty Cycle
// that changes.

oPWMH A = New oPWMH;

Void Main(Void){
  A.IOLine = 17;
  A.Operate = 1;
  Do{
    A.DutyCycle.Inc;
    Delay = 10;
  }
}

Basic Syntax

'This program causes 
' I/O Line 17 To 
' output a PWM signal.
' with a Duty Cycle
' that changes.

A As oPWMH(17,,cvOn)

Do
  A.DutyCycle.Inc
  Delay = 10
Loop