Silicon Labs Simplifies Audio Development With Class D ToolStick Board

Silicon Labs’ highly integrated SiM3U1xx MCUs are well suited for digital Class D power amplification applications without the hassle and expense of adding discrete Class D amplifiers. The SiM3U1xx MCUs include a 300 mA high-drive I/O capable of directly driving a small speaker, a crystal-less USB transceiver compatible with the USB audio interface, two 250 ksps 12-bit analog-to-digital converters, and an I2S receiver that supports audio streaming from a PC, a portable music player or a wide range of I2S-enabled audio devices. The only external components required to drive Class D audio from SiM3U1xx MCUs are inexpensive inductors, some capacitors and ferrite beads.



In addition to supporting Class D audio capabilities, the new ToolStick also enables developers to add capacitive touch buttons and sliders to their 32-bit embedded systems or use the SiM3U1xx MCU’s high-drive I/Os with pulse-width modulation to directly drive other components such as small motors, eliminating the need for separate power field-effect transistors.



The Class D ToolStick board is powered from USB using the SiM3U1xx MCU’s internal 5 V regulator, and it can play music from a stereo jack, a computer or a recorded message using a simple speaker. The Class D ToolStick provides four modes of operation: sampling data from a portable music player using the MCU’s on-chip ADCs, USB audio streaming from a PC, playing pre-recorded sound clips stored from on-chip flash memory using a common audio compression algorithm, and a voice recorder that stores data in flash using an audio compression algorithm. Developers can easily handle mode transition through capacitive touch buttons and control volume with a capacitive touch slider.



The Class D ToolStick evaluation kit comes complete with hardware Gerber files and software to streamline the process of adding Class D audio to embedded applications. In addition, the ToolStick can serve as a cost-effective, general-purpose development platform for Precision32 MCUs. It features a built-in USB-based debugger/programming interface and accessible pins for easy prototyping. The Class D ToolStick debug interface is fully operational with Silicon Labs’ complimentary Precision32 IDE, compiler and AppBuilder crossbar configuration software, as well as Keil tool chains.



“Audio feedback provides developers with a useful, cost-effective and appealing way to differentiate their embedded products in today’s competitive market,” said Keith Odland, director of marketing for Silicon Labs’ microcontroller products. “With our new Class D ToolStick, developers can quickly and easily add Class D audio capabilities and capacitive touch buttons and sliders to any 32-bit embedded product using Silicon Labs’ SiM3U1xx MCUs.”



The Class D ToolStick evaluation kit is available now and priced at $35 (USD MSRP). The kit includes full source code and implements a Class D amplifier demonstration using a small-footprint 40-pin 6 mm x 6 mm package SiM3U1xx MCU.