NXP Application Code Hub

Real-Time ADC Monitoring and LED Dimming Using FreeMASTER

This example demonstrates how to control the brightness intensity of an LED using the FreeMASTER debugging tool GUI on the FRDM-A-S32K344 development board, leveraging the eMIOS peripheral for PWM generation.

The example uses the AUTOSAR Adc driver TempSense API to continuously poll the on-die temperature sensor, converts the Q11.4 fixed-point result to degrees Celsius, and exposes the reading as a global variable (temperature) via the FreeMASTER real-time data visualization tool over LPUART6.

Boards: FRDM-A-S32K344

Categories: Analog Front End, User Interface

Peripherals: eMIOS, ADC, UART

Toolchains: S32 Design Studio IDE

Table of Contents

1. Software and Tools
2. Hardware
3. Setup
4. Results
5. Support
6. Release Notes

1. Software and Tools

This example was developed using the FRDM Automotive Bundle for S32K3 + S32M27. To download and install the complete software and tools ecosystem, use the following link:

• FRDM Automotive S32K3 + S32M27 Board Installation Package

In addition, the FreeMASTER run-time debugging tool is required to visualize the sensor data:

• FreeMASTER Run-Time Debugging Tool

2. Hardware

2.1 Required Hardware

• Personal Computer
• Type-C USB cable
• FRDM-A-S32K344

  

2.2 Debugger Connection

• Connect the Type-C USB cable to PC and FRDM-A-S32K344 board for power supply and debugging

3. Setup

3.1 Import the Project into S32 Design Studio IDE

1. Open S32 Design Studio IDE, in the Dashboard Panel, choose Import project from Application Code Hub.

   

2. Find the demo by searching: Real-Time ADC Monitoring and LED Dimming Using FreeMASTER

3. Open the project, click the GitHub link, S32 Design Studio IDE will automatically retrieve project attributes, then click Next>.

   

4. Select main branch and then click Next>.

5. Select your local path for the repo in Destination->Directory: window. The S32 Design Studio IDE will clone the repo into this path, click Next>.

6. Select Import existing Eclipse projects then click Next>.

7. Select the project in this repo (only one project in this repo) then click Finish.

3.2 Generating, Building and Running the Example

1. In Project Explorer, right-click the project and select Update Code and Build Project. This will generate the configuration (Pins, Clocks, Peripherals), update the source code and build the project using the active configuration (e.g. Debug_FLASH). Make sure the build completes successfully and the *.elf file is generated without errors.

   

   Press Yes in the SDK Component Management pop-up window to continue.

2. Go to Debug and select Debug Configurations. There will be a debug configuration for this project:

   

    Configuration Name                  Description
    -------------------------------     -----------------------
    $(example)_debug_flash_pemicro      Debug the FLASH configuration using PEmicro probe
   

   Select the desired debug configuration and click on Debug. Now the perspective will change to the Debug Perspective. Use the controls to control the program flow.

3.3 How It Works

After initializing the MCU clocks, pin mux (Siul2_Port_Ip_Init and Port_Init), eMIOS PWM, LPUART, and ADC (including a self-calibration pass with Adc_Calibrate), FreeMASTER is configured to use LPUART6 as its serial transport via FMSTR_SerialSetBaseAddress((FMSTR_ADDR)IP_LPUART_6_BASE), then initialized with FMSTR_Init().

The application drives a non-blocking "breathing" LED effect on an eMIOS PWM channel: the duty cycle ramps up and down in a smooth triangular pattern using Pwm_SetDutyCycle(). The brightness updates on every loop pass — FMSTR_Poll() is called first so the FreeMASTER link never times out, followed by a short TestDelay(breathe_poll_delay) that paces both the animation speed and the serial polling rate.

Three global variables tune the effect and can be watched and changed live from FreeMASTER:

• breathe_duty_max - peak brightness (PWM duty, 0x8000 = 100%).
• breathe_speed - brightness change applied on every loop pass (smaller = smoother, slower ramp).
• breathe_poll_delay - simulates the CPU load; higher values will affect FreeMASTER link reliability.

In parallel, Adc_TempSenseGetTemp() reads the on-die temperature sensor; the Q11.4 result is converted to degrees Celsius into the global temperature variable, and error_flag is set if a conversion fails. The live PWM duty is mirrored in dutyCycle.

User controls: two board push-buttons (SW2/SW3, detected via ICU falling-edge interrupts) increase/decrease breathe_speed. The same control is also available from the PC: a custom FreeMASTER control page (include_freemaster/breathing_control.htm) provides knobs and +/- buttons that read and write these variables in real time.

4. Results

Results are visualized using the FreeMASTER Run-Time Debugging Tool PC application.

1. After generating the .elf file, run the application on the FRDM-A-S32K344 board.
2. Open FreeMASTER on your PC and load the FRDM_A_S32K344_ADC_POT_LED_EMIOS.pmpx project file.
3. In FreeMASTER, click the GO! green button (Start Communication) to connect; it will search the COM port of the board at baud rate 115200.
4. The temperature variable will update in real time, showing the on-die temperature in degrees Celsius.
5. If the ADC conversion fails, the error_flag variable will be set to true.
6. Use the knobs Peak brightness and Breathe Speed to change the dutyCycle variable; this will update the LED behavior in real time.
7. See the changes in the DutyCycle LED plot on the FreeMASTER application below:

   

5. Support

For general technical questions related to NXP microcontrollers, please use the NXP Community Forum.

Project Metadata

Questions regarding the content/correctness of this example can be entered as Issues within this GitHub repository.

Note: For more general technical questions regarding NXP Microcontrollers and the difference in expected functionality, enter your questions on the NXP Community Forum

6. Release Notes

Version	Description / Update	Date
1.0	Initial release on Application Code Hub	October 8th 2026