3.2.3 Low Power Acoustic Detection With Integrated Data Logging on PIC32CM GV VL Curiosity Nano+ Touch Evaluation Kit

Description

This demonstration aims to showcase the detection of acoustic noise and low power monitoring using the PIC32CM GV-Value Line Curiosity Nano+ Touch evaluation kit, in conjunction with the Curiosity Nano Explorer for the microphone and SPI EEPROM and PAC1944 Power Monitor.

The application operates in a two distinct functionalities: Acoustic Detection with Data Logging and Low Power Monitoring, based on the user-controlled Touch button.

• Acoustic Detection: Following a device reset, set the RTC time and date before entering the Datalog mode. The system enters acoustic detection mode only when the Touch button is pressed. The LED is turned ON and the system continuously monitors the environment for acoustic noise events during that time. Upon detecting an event, it records the event time using the RTC and stores it as a log entry in the EEPROM through SPI communication. The system writes real-time log entries to the EEPROM. The logged data is read back from the EEPROM through SPI and displayed on the terminal through UART for user review.
• Low Power Monitoring: To enter the low-power standby sleep mode, the system requires a touch input during data logging. Once the Touch button is pressed again, the LED turns OFF, indicating that the system has exited Datalog mode and entered low-power standby sleep mode. In this state, if any interrupt is generated during this state, the device wakes up immediately and returns to Active mode. The microcontroller unit (MCU) significantly reduces power consumption by disabling non-essential peripherals and lowering the clock frequency. This mode showcases the low-power capabilities of the PIC32CM GV-Value Line Curiosity Nano+ Touch evaluation kit.

Modules/Technology Used

The following figure provides the MCC Harmony project graph with all the components.

Hardware Used

Software/Tools Used

Refer to the Project Manifest present in harmony-manifest-success.yml under the project folder firmware/src/config/pic32cm_gv_vl_cnano.

• Refer to the Release Notes to know the MPLAB X IDE and MCC Plug-in version
• Any Serial Terminal application, such as Tera Term/PuTTY terminal application

Due to Microchip regularly updates tools, occasionally issue(s) could be discovered while using the newer versions of the tools. If the project does not seem to work and version incompatibility is suspected, it is recommended to double-check and use the same versions that the project was tested with. To download original version of MPLAB Harmony v3 packages, refer to the document How to Use the MPLAB Harmony v3 Project Manifest Feature (DS90003305).

Hardware Setup

Programming Hex File

The pre-built hex file can be programmed by following the below steps.

Programming/Debugging Application Project

Running the Demo

• Ensure that a connection is established between the USB Bridge port of the Curiosity Nano board and the host PC using a USB cable.
• Open the Tera Term/PuTTY terminal application on the PC (from the Windows® Start menu by pressing the Start button)
• Set the baud rate to 115200
• Reset the device by pressing the CNANO RESET button on the Curiosity Nano Explorer board

  

• The device will start running the demo and the terminal will display the following message

  

• Before entering the Datalog mode, set the RTC time and date in the following format: DD-MM-YYYY HH:MM:SS (e.g., 08-07-2025 14:30:00).
  Note: The RTC is not synchronized with any external network or real-time source in this application. Therefore, the current date and time are not automatically updated. Instead, the system uses the date and time manually provided by the user through the serial terminal. The RTC then continues from this manually set value to log acoustic detection events.

  

• Press the Touch button on the PIC32CM GV-Value Line Curiosity Nano+ Touch evaluation kit to enter Data log mode. The LED turns ON, and the microphone on the Curiosity Nano Explorer Board continuously monitors the acoustic events along with their timestamps.

  

• The system captures and stores acoustic data logs with timestamps in the EEPROM through SPI, and the observed logs are printed on the terminal through UART

  

• To enter Low Power Standby Sleep mode, press Touch button again during data logging. The LED turns OFF, and the system displays the following message on the terminal.

  

• Ensure the connection between the PIC32CM GV-Value Line Curiosity Nano+ Touch evaluation kit and the PAC1944 Power Monitor - CH1 on the Curiosity Nano Explorer board as mentioned in the above hardware setup.
• To monitor the power consumption of the device, open the PAC194x 5x Demo Application and follow the steps below:
  1. Ensure the message Board connected appears at the bottom-left of the Status section.
  2. Select and set the Average N AVG Values to 20. (The value can be adjusted based on the desired sampling accuracy).
  3. Click the Start Acquisition button.
  4. Monitor the power consumption on Current Avg (mA) in the Real Data section of CH1.

     

  5. Once the Start Acquisition button is clicked, Real data of power consumption will appear in the Current Avg (mA) section.
• The image below shows the device's power consumption in standby mode as 46 µA
  Note: The average value is considered when measuring the power consumption of the device due to the instant value is not stable. Then, the power consumption of the device in Standby mode is 46 µA.

  

  Note: The following clock configuration is optimized to achieve low power consumption of the PIC32CM GV-Value Line Curiosity Nano+ Touch evaluation kit MCU with the necessary peripheral functionality.
  1. Main Clock: DFLL configured at 48 MHz and used as the source for GCLK0.
  2. GCLK1: Sourced from XOSC32K and runs at 1024 kHz.
  3. GCLKx: Sourced from OSCULP32K and runs at 32.768 kHz.
  4. Peripheral Clock configurations:
     • RTC, SYSCTRL_DFLL48, TC0, EVSYS, and AC are clocked at 1024 Hz (via GCLK1)
     • PTC clocked at 32,768 Hz (via GCLK2)
     • SERCOM2 and SERCOM5 are clocked at 48 MHz (via DFLL through GCLK0)
• To generate an interrupt that wakes the device from Standby mode to Active mode. This action increases power consumption, and the device immediately returns to Standby mode after device wakes up.
  Note: The power consumption is lower in Standby mode than in Active mode.

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