Advanced MCUs Bring AI to Cost-Sensitive Applications
Because health trackers must be compact and lightweight, they require compact MCUs with integrated analog and digital peripherals that occupy only a few square millimeters of PCB real estate.
Other applications that can make use of NNs include smart home systems. Such systems often employ an audio subsystem charged with detecting a spoken wakeup word. This subsystem typically includes:
- An analog microphone to capture the user’s voice.
- An AFE to provide amplification and filtering.
- An ADC to provide digitization.
- An Inter-IC Sound (I2S) or time-division multiplexing (TDM) interface to carry the digitized signal to the DSP- and NN-equipped MCU.
Because the function must operate continuously to listen for the wakeup word, its components must be low power yet sufficiently responsive that users need not repeat the wakeup word. If a valid wake-up word has been spoken, control can be transferred to a more powerful local processor or cloud-based AI model.
Texas Instruments reports that for such applications, it offers NPU-equipped MCUs that consume only tens of milliwatts, compared to the watts of power required for typical voice-processor integrated circuits. The company also reports that an AI keyword recognition model using a one-dimensional convolutional NN can reduce processing time by more than 90X compared to running the same model on a standard MCU.
Yet another edge-AI application is industrial-motor vibration detection, which can be used to schedule predictive maintenance for conveyers, pumps, or other motor-driven equipment. In such equipment, local AI models running on an MCU are able to extract time-domain anomalies such as impulse spikes and irregular periodicity that can indicate impending failure.
In such systems, accelerometers monitor mechanical vibration, and as in wearable and smart home systems, an AFE, ADC, and DSP and NN-equipped MCU complete the signal chain necessary to provide output classification and anomaly detection.
80-MHz MCU with NPU
To power such applications, TI offers the MSPM0G5187 mixed-signal MCU with a TinyEngine NPU (Fig. 2). This device includes a 32-bit Arm Cortex-M0+ CPU operating up to 80 MHz with up to 128 kB of flash memory and up to 32 kB of SRAM. Analog peripherals include a 12-bit, 1.6-MSPS ADC supporting up to 26 external channels, a high-speed comparator with integrated reference, a digital-to-analog converter (DAC), and two voltage references.
