Embedded Systems Conference, Boston, Mass. — ST has announced free speech and DSP libraries for the STM32, its ARM Cortex-M3 microcontroller. The speech compression library implements the open-source Speex codec. This codec is pre-configured to use the chip's IO and memory resources. It samples speech at 8 KHz using the on-chip 12-bit ADC and stores the compressed output in on-chip Flash at 1 KB/sec. Speech is played back through the chip's PWM.
The DSP library offers a variety of fast Fourier transforms (FFTs), and finite impulse response (FIR) and infinite impulse response (IIR) filters. The DPS library also includes a PID controller. ST claims that its libraries are highly optimized. For example, a 256-point radix-4 FFT executes in 362 us on a 72 MHz STM32.
The speech and DSP are written in a mix of assembly and C, and support the Keil, IAR, and Raisonance tool chains. Both libraries are available for free download at www.st.com/mcu.
Kenton Williston has been writing about DSP technology and business trends since 2001. Prior to running the DSP DesignLine, he was the editor and the senior contributor for Inside DSP. He is an author of numerous technology reports, including the Buyer's Guide to DSP Processors. Kenton is a popular presenter at the Embedded Systems Conference and other venues, and he has advised the leading DSP semiconductor firms on their marketing and product-planning strategies. You can contact him at .