University of California Santa Cruz Baskin School of Engineering CSE121 & CSE121L Spring 2022 Lab 1 Copyright ? 2022 David C. Harrison. All rights reserved.

CSE121 & CSE121L Spring 2022

Lab 1

In this lab you will gain basic familiarity with the PSoC 6 BLE Prototyping Kit (which we’ll just call ‘PSoC 6’ from
now on) and the PSoC Creator IDE you will be using for subsequent labs.

Specifically, you will write programs to blink the PSoC 6’s internal LEDs in four different ways. All programs are
examples of setting the values (voltages) of digital pins on the PSoC 6.

This assignment is worth 5% of your final grade.


Setup

1. Connect your PSoC 6 to a USB port on a lab workstation using the USB 2.0 A male to female cable from your
components kit and the short USB A female to micro male cable from the PSoC 6 package.

2. Update the firmware on your PSoC 6 by starting PSoC Programmer, selecting the Utilities tab and clicking
Upgrade Firmware. Then disconnect then re-connect your PSoC 6.

3. Start PSoC Creator and create a workspace.
File New Project…
Select Workspace then Next
Set Workspace name to CSE121 and click Finish

4. Set the PDL V3 path to C:\Program Files (x86)\Cypress\PDL\3.1.5 ( or 3.1.3 )
Tools Options Project management

5. Create an empty project that can be used to re-set you PSoC 6 to a known state.
File New Project…
Set Target device to PSoc 6 and Launch Device Selector
In Device Selector, scroll down and select CYBLE-416045-02 then click OK
Click Next
Select Empty schematic and click Next
Click Next again
Set Project name to Lab1.0 and click Finish
Build Generate Application
Debug Select target and program
Select PSoC 6 CYBLE-416045-02 (CM4) and OK / Connect
Watch for output in the window at the bottom of PSoC Creator
When you see Device ‘PSoC 6 CYBLE-416045-02 (CM4)’ was successfully programmed you have
successfully created the empty project and programmed your PSoC 6.

Background information

Pulse Width Modulation

A Pulse-Width Modulator (PWM) is a component used by digital systems to generate control signals for hardware.
Its periodic rectangular (modified square) signal can be used for many applications including driving a speaker,
rotating a servo motor, or making an LED blink at a regular interval.

By adjusting the duty cycle (portion of the period that the power is on), a PWM can be used to control the average
power supplied, which can be used for a variety of functions including dimming an LED as we’ll see in Lab 2.

For more details see: https://en.wikipedia.org/wiki/Pulse-width_modulation
University of California Santa Cruz Baskin School of Engineering CSE121 & CSE121L Spring 2022 Lab 1 Copyright ? 2022 David C. Harrison. All rights reserved.

Requirements

Lab 1.1 Hardware Only

Whilst the PSoC 6 has two CPUs, it is possible to have on-board hardware set the values of digital pins without
the involvement of either CPU. Here you will drive the on-board PWM with an on-board clock to switch the voltage
of the digital pins the two internal LEDs are connected to from high to low (zero volts) every half second.

Lab 1.2: Single CPU

Have the PSoC 6’s CM0+ CPU switch the voltage of the digital pins the two internal LEDs are connected to by
making use of the PSoC 6 Peripheral Driver Library, details of which can be found on-line on the manufacture’s
web site: https://infineon.github.io/psoc6pdl/pdl_api_reference_manual/html/index.html

Lab 1.3: Multiple CPUs

By using the PSoC 6 Peripheral Driver Library, have the PSoC 6’s CM0+ CPU switch the voltage of the digital pin
one the two internal LEDs is connected to and have the PSoC 6’s CM4 CPU switch the voltage of the digital pin
the other internal LED is connected to.

Lab 1.4: FreeRTOS

The code from Lab1.2 and Lab1.3, whilst easy to understand, is inefficient and difficult to scale as we must maintain
the main program loop ourselves. For more realistic embedded systems it is convenient to use a “Real Time
Operating System” (RTOS) to schedule period tasks. Here we deploy FreeRTOS (https://www.freertos.org) on the
PSoC 6’s CM4 CPU and write tasks to independently switch the voltage of the digital pins the two internal LEDs
are connected to using the PSoC 6 Peripheral Driver Library.


What steps should you take to tackle this?

Lab 1.1 Hardware Only

1. Create a new project in the CSE121 workspace:
File New Project…
Set Target device to PSoc 6 and Last used: CYBLE-416045-02
Click Next
Select Empty schematic and click Next
Click Next again
Set Project name to Lab1.1 and click Finish

2. Add two digital pins:
Open TopDesign.cysh
Add a digital pin from Ports and Pins and change its Name to RED
Add a second digital pin and change its Name to GREEN

3. Add a PWM:
Add a PWM from Digital ? Functions and change its Name to PWM
Set the PWM Period 0 to 999
Set the PWM Compare 0 to 500

4. Add a clock:
Add a Clock from System and change its Name to Clock
Set the clock Frequency to 1KHz

5. Connect the components:
Use the Wire Tool to connect the clock to the clock port on the PWM
Use the Wire Tool to connect the PWM pwm port to the RED digital pin
Use the Wire Tool to connect the PWM pwm_n port to the GREEN digital pin
University of California Santa Cruz Baskin School of Engineering CSE121 & CSE121L Spring 2022 Lab 1 Copyright ? 2022 David C. Harrison. All rights reserved.

6. Confirm your TopDesign.cysh looks like this:

7. Set the digital pin port numbers in “Design Wide Resources”:
Set GREEN to port P7[1]
Set RED to port P6[3]

8. Generate software / firmware components.
Build Generate Application

9. Disable CM4, enable the PWM and put CM0+ to sleep:
Edit CM0p Source Files main_cm0p.c
Remove the call to Cy_SysEnableCM4()
Remove the infinite loop for (;;) { }
Start the PWM by adding a call to PWM_Start()
Put CM0+ to sleep by adding a call to Cy_SysPm_Sleep(CY_SYSPM_STATUS_CM0_SLEEP)
Save main_cm0p.c

10. Program the PSoC 6:
Debug Select target and program
Select PSoC 6 CYBLE-416045-02 (CM4) and click OK / Connect
Watch for Device ‘PSoC 6 CYBLE-416045-02 (CM4)’ was successfully programmed’

If all goes well, the red and green on-board LEDs will start blinking on a half second cycle, red on, green off,
green on red off, etc.

Lab 1.2: Single CPU

1. Create a new project in the CSE121 workspace:
As above, but name it Lab1.2

2. Add two digital pins:
As above, but uncheck their General ? Digital output ? HW connection properties

3. Set the digital pin port numbers in "Design Wide Resources":
Set GREEN to port P7[1]
Set RED to port P6[3]

4. Generate software / firmware components
Build Generate Project

5. Disable CM4
Edit CM0p Source Files main_cm0p.c
Remove the call to Cy_SysEnableCM4()

University of California Santa Cruz Baskin School of Engineering CSE121 & CSE121L Spring 2022 Lab 1 Copyright ? 2022 David C. Harrison. All rights reserved.

6. Modify the main control loop to set the RED LED on and off on a half second delay:
Cy_GPIO_Write(RED_PORT, RED_NUM, x); // x = 1 for on, 0 for off
CyDelay(500); // sleep for 500ms

7. Modify the main control loop to do the opposite for GREEN LED on:

8. Program the PSoC 6:
Debug Select target and program
Select PSoC 6 CYBLE-416045-02 (CM4) and OK / Connect
Watch for Device ‘PSoC 6 CYBLE-416045-02 (CM4)’ was successfully programmed’

Lab 1.3: Multiple CPUs

1. As Lab1.2, but with the following differences:
Project name is Lab1.3
Do not disable CM4
Only toggle the RED LED in the CM0+ control loop
Toggle the GREEN LED in the CM4 main control loop

Lab 1.4: FreeRTOS

1. As steps 1 to 3 in Lab1.2, but with the following differences:
Project name is Lab1.4

2. Include support for FreeRTOS:
Use the (right mouse) context menu on the Lab1.4 project:
Build Settings Peripheral Driver Library
Select RTOS FreeRTOS Memory Management ( variant heap_1 )

3. Generate software / firmware components
Build Generate Application

4. Include FreeRTOS header files:
Edit CM4 Source Files main_cm4.c
Hash include FreeRTOS.h and task.h

5. Write a FreeRTOS task start function to toggle the RED LED:
Signature must be void red_task(void *arg)
Use Cy_GPIO_Write to set the pin status as before
Use vTaskDelay instead of CyDelay

6. Intialise a FreeRTOS task to call the start function:
xTaskCreate(red_task, "RED_TASK", 400, NULL, 1, 0);
Study the documentation to understand what the arguments to xTaskCreate signify

7. Repeat steps 5 and 6 for the GREEN LED

8. Start the FreeRTOS task scheduler
Remove the generated infinite loop
Replace with a call to vTaskStartScheduler();

9. Program the PSoC 6:
Debug Select target and program
Select PSoC 6 CYBLE-416045-02 (CM4) and OK / Connect
Watch for Device ‘PSoC 6 CYBLE-416045-02 (CM4)’ was successfully programmed’

University of California Santa Cruz Baskin School of Engineering CSE121 & CSE121L Spring 2022 Lab 1 Copyright ? 2022 David C. Harrison. All rights reserved.

How much code will you need to write?

Almost none. Your FreeRTOS implementation can be factored to avoid duplication, but make sure you have a
simple if inefficient version working before moving on to anything more sophisticated.

Grading scheme

The following aspects will be assessed:

1. (100%) Does it work?

Lab 1.1 Hardware Only (25%)
Lab 1.2 Single CPU (25%)
Lab 1.3 Multiple CPUs (25%)
Lab 1.4 FreeRTOS (25%)

How will you get your work graded?

Submit as described below, then in a TA office hours session, or lab section, demonstrate all four programs to a
TA. They will only award you a grade if you have submitted your code.

What to submit

In PSoC Creator, select:

Build Clean All Projects

Then open PowerShell:

$ cd '.\Documents\PSoC Creator\CSE121'
$ Compress-Archive -Path Lab1.* -DestinationPath CSE121-Lab1.zip

This creates an archive named CSE121-Lab1.zip in the current directory.