Nancyvarkey at 10:07, 14 January 2021

2021-01-14T10:07:35Z

Nirmala Venkat: Created page with " {| border="1" |- | align=center| '''Visual Cue''' | align=center| '''Narration''' |- || Slide 1: || Welcome to the spoken tutorial on '''PWM Instruction''' |- || Slide 2:..."

2020-12-29T08:33:46Z

Created page with " {| border="1" |- | align=center| '''Visual Cue''' | align=center| '''Narration''' |- || Slide 1: || Welcome to the spoken tutorial on '''PWM Instruction''' |- || Slide 2:..."

New page

{| border="1"
|-

| align=center| '''Visual Cue'''
| align=center| '''Narration'''
|-
|| Slide 1:
|| Welcome to the spoken tutorial on '''PWM Instruction'''
|-
|| Slide 2:

Learning Objectives
* PWM (Pulse Width Modulation) instruction

||

In this tutorial we’ll learn about working of
* Pulse Width Modulation instruction
|-
|| Slide 3: System Requirements
* Ubuntu 18.04''' '''OS
* LDmicro
* OpenPLC V1 Mainboard
* 24V, 2A SMPS
* USBasp programmer
* Heater module

|| To record this tutorial I am using:
* '''Ubuntu Linux 18.04''' operating system
* '''LDmicro'''
* '''OpenPLC version 1 Mainboard'''
* '''24V, 2A SMPS'''
* '''USBasp programmer'''
* '''Heater module'''
|-
|| Slide 4: Pre-requisites
* Heater module
* Working of '''Move''' instruction.

If not, please refer to the relevant tutorials from [https://spoken-tutorial.org/ Home | spoken-tutorial.org]
|| To follow this tutorial, you should know about
* Heater module and
* Working of '''Move''' instruction.

If not, please refer to the relevant tutorials in this series on this website.
|-
|| Slide 5: Prerequisites - Hardware setup

hardware-prerequisite.jpg
|| Connect''' SMPS''' and '''USBasp''' to the '''Mainboard''' as shown in the picture.

Keep these connections throughout this tutorial.
|-
|| Slide 6a: PWM instruction
* Can set the duty cycle of the PWM peripheral built into certain microcontrollers
* Duty cycle must be a number between 0 and 100

|| This sets the duty cycle of the PWM peripheral built into certain microcontrollers.

Duty cycle must be a number between 0 and 100.
|-
|| Slide 6b: PWM instruction
* PWM frequency specified might not be exactly achievable.
* It depends on microcontroller's clock frequency

|| We can specify the '''PWM''' frequency in '''Hertz'''.

The frequency specified might not be exactly achievable.

It depends on how it divides into the microcontroller's clock frequency.
|-
|| Show image of heater module
|| Here, we will create a logic to control the speed of a fan using '''PWM'''.

We will use the fan in the Heater module.
|-
|| Open the LDmicro from the launcher bar
|| Let us open '''LDmicro'''.
|-
|| Click Instructions -> Insert Contact >> Place the cursor to the right of the contact >> Click Instructions -> Insert MOV
|| Insert a '''Contact'''.

Place the cursor to the right of the Contact and insert a '''Move''' instruction.
|-
|| Double-click on Xnew >> Type switch1 in the name box >> Click the OK button
|| Rename the '''Contact''' as '''‘switch1’'''.
|-
|| Double-click on the MOV >> Set Destination to dc >> Set Source to 20 >> Click the OK button
|| In the move instruction set the variable dc to 20.

Click on the OK button.
|-
|| Click Edit -> Insert rung below >> Click Edit -> Insert rung below
|| Now, insert a rung below the current rung.
|-
|| For both the rungs

Click Instructions -> Insert Contact >> Place the cursor to the right of the contact >> Click Instructions -> Insert MOV
|| In the new rung insert a '''Contact''' and a '''Move''' instruction as shown.
|-
|| Double-click on Xnew >> Type switch2 in the name box >> Click the OK button

Double-click on the MOV >> Set Destination to dc >> Set Source to 60 >> Click the OK button
|| Rename the '''Contact''' as '''‘switch2’'''.

In the '''Move''' instruction set the variable dc to 60.
|-
|| Click Edit -> Insert rung below >> Place the cursor in the new rung
|| Insert one more rung below.

|-
|| Insert Instructions -> Analog Operations -> Insert Set PWM output
|| Now, insert a '''PWM''' instruction from '''‘Analog Operations’''' as shown here.
|-
|| Double-click on PWM
|| Double-click on it.
|-
|| Highlight two columns
|| We can find two columns.
|-
|| Highlight Duty cycle variable

Type dc
|| First one is the duty cycle variable.

Set it to variable ‘'''dc’'''.
|-
|| Highlight Frequency
|| Second is Frequency in '''Hertz'''.

By default, it is set to 1kHz i.e. 1000Hz.

Do not change it.
|-
|| Click the OK button
|| Click the '''OK''' button.
|-
|| Highlight dc type in the I/O list
|| In the I/O list we can see the variable '''‘dc’''' is of type '''PWM out.'''
|-
||
|| We will now check the working of this logic
|-
|| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
|| Let us turn on the simulation mode.

For that, click '''Simulate''' and then on '''Simulation mode.'''

Next, start real-time simulation as shown.
|-
|| Highlight state column in the IO list
|| We can observe initially the states of all the instructions are 0.
|-
|| Double click on Xswitch1
|| Change the state of '''Xswitch1''' to 1 by double-clicking on it.
|-
|| Highlight the value of dc
|| The variable '''dc''' is set to 20.
|-
||

Highlight the value of dc

|| The '''dc''' variable value is set as the duty cycle of the PWM peripheral.

This happens when the input condition of PWM instruction is true.

In our case, it is true as the PWM instruction is connected to the positive rail.
|-
|| Double click on Xswitch1
|| Change the state of '''Xswitch1''' back to 0.
|-
|| Double click on Xswitch2

Highlight the value of dc

Double click on Xswitch2
|| Similarly, when '''Xswitch2''' state is 1 the duty cycle will be set to 60.
|-
||
|| Make sure that at a time only one of the Contacts has its state 1.
|-
|| Click Simulate -> Halt simulation >> Click Simulate -> Simulation Mode
|| Now, turn off the simulation mode.

For that, click '''Simulate''' and then on '''Halt Simulation.'''

Then click '''Simulate''' and '''Simulation Mode.'''
|-
||
|| Now let us compile the logic.
|-
|| Click on Settings >> Click on Microcontroller >> Select AVR ATmega16 40-PDIP

Click on Settings >> Click on MCU parameters >> Change Crystal frequency to 16
|| Click on '''Settings''' and select the microcontroller '''AVR ATmega16 40-PDIP.'''

Adjust its parameters as shown here.
|-
|| Highlight ‘dc’ in the I/O list
|| We can see that variable '''dc''' is already assigned pin number 21, which is '''PD7'''.

This is the PWM pin for '''ATMega16''' microcontroller.
|-
|| Double-click on Xswitch1 in I/O list >> Select PC7 >> Click OK button

Double-click on Xswitch2 in I/O list >> Select PC6 >> Click OK button
|| Now assign '''PC0''' to '''Xswitch1 '''and '''PC1''' to '''Xswitch2''' as shown.

|-
|| Click on Compile >> Click on Compile >> rename it as ‘pwm.hex’ >> Go to Desktop/LDmicro folder >> Click on Save.

Click OK button
|| Compile the logic as''' pwm.hex'''
|-
|| Click on File >> Click on Save >> Rename it as ‘pwm.ld’ >> Go to Desktop/LDmicro folder >> Click on Save
|| Save the ladder diagram as '''pwm.ld'''
|-
||
|| We will now see the working of this logic on hardware.
|-
|| Connect Mainboard to PC using USBasp

laptop-usbasp.jpg

|| Connect the '''Mainboard''' to your laptop using '''USBasp'''.

Turn on the power supply.
|-
|| Open terminal >> Type cd Desktop/LDmicro >> Press ENTER >> type ‘'''avrdude -c usbasp -p m16 -U flash:w:pwm.hex’ '''>> Press ENTER
|| Open the Terminal by pressing '''CTRL+ALT+T''' keys simultaneously.

Go to the folder where you have saved the hex file.

Type the command as shown to upload the hex file to the '''Mainboard'''.
|-
|| Remove the '''USBasp''' connection from the laptop.
|| Turn off the power supply.

Remove the '''USBasp''' connection from the laptop.

This will prevent any hardware damage.
|-
|| pwm.png
|| Let us see the connection details now.
|-
|| pwm.png
|| Power the''' Heater module''' through relimate connectors from the '''Mainboard'''.

Connect '''PD7''' to the fan pin of the '''MCU''' pins of the '''Heater module.'''
|-
|| pwm.png
|| Connect '''GND''' and 5V of the '''Switchboard''' to '''GND''' and 5V of the '''Mainboard''' respectively.

Then connect '''NO1''' to '''PC0''' and '''NO2''' to '''PC1 '''of the '''Mainboard'''.

Make the connections as shown in the picture.
|-
||
|| After making all the connections properly, turn on the power supply.
|-
||
|| Initially the fan will be off as the duty cycle is 0.

The '''FANon''' LED on the Heater module would be glowing dim.

Press the switch '''NO1'''.

We can observe the fan is turned ON.

The duty cycle is 20 here.
|-
||
|| Now press the switch '''NO2'''.

We can observe the speed of the fan is increasing comparatively.

This is because of the increase in the duty cycle to 60.
|-
||
|| Thus we have controlled the speed of the fan using '''PWM'''.
|-
||
|| Turn off the power supply.
|-
||
|| This brings us to the end of this tutorial.

Let us summarize.
|-
|| Slide 8: Summary
* PWM instruction

|| In this tutorial we learnt about working of * PWM instruction

|-
|| Slide 9:

Assignment:

|| As an assignment,

Control the brightness of the red LED of Traffic Light module.

Hints: Replace fan of Heater module with red LED of Traffic light module.
Connect PD7 pin to +5V pin of the red LED of the Traffic Light module.
|-
|| Slide 10:

About Spoken Tutorial project
|| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.
|-
|| Slide 11:

Spoken Tutorial workshops
|| The''' Spoken Tutorial Project''' team:
* conducts workshops using spoken tutorials and
* gives certificates on passing online tests.

For more details, please write to us.
|-
|| Slide 11:

Forum for specific questions:
|| * Please post your timed queries in this forum.

|-
|| Slide 12:

Forum for specific questions:
|| Do you have any general / technical questions on OpenPLC?

Please visit the FOSSEE forum and post your question.
|-
|| Slide 13:

Acknowledgement
|| Spoken Tutorial Project is funded by MHRD, Government of India.
|-
|| Slide 14:

Thank you slide
|| This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.

And this is Harsha Priyanka from FOSSEE team, signing off.

Thanks for watching.
|-
|}

OpenPLC-version1-with-LDmicro/C3/PWM-Instruction/English - Revision history

Nancyvarkey at 10:07, 14 January 2021

Nirmala Venkat: Created page with " {| border="1" |- | align=center| '''Visual Cue''' | align=center| '''Narration''' |- || Slide 1: || Welcome to the spoken tutorial on '''PWM Instruction''' |- || Slide 2:..."