USB microphone offers high quality audio for online meetings and livestreaming

Convergent Design

Convergent Design’s Erika employs Nordic’s nRF52833 SoC to provide a wireless, miniaturized audio solution

Nordic Semiconductor today announces that Convergent Design, a Colorado Springs, CO-based developer of media recording and monitoring solutions, has selected Nordic’s nRF52833 multiprotocol System-on-Chip (SoC) to provide the wireless connectivity between its ‘Erika’ USB microphone, and a PC or Mac.

Enhanced ShockBurst technology

Designed for online meetings, livestreaming, webinar and podcasting applications, the all-in-one microphone, transmitter and battery comes in a lightweight (16g) form factor that is magnetically attached to the user’s lapel or clothing, and eliminates the need for an additional body pack, wires, or buttons. In operation, the user simply plugs a USB receiver into a host device—for example a desktop or laptop computer—to ensure wireless connectivity between Erika and the USB receiver. The wireless link uses Nordic’s 2.4GHz proprietary protocol with Enhanced ShockBurst (ESB) technology. 

Both the microphone and the USB receiver integrate an nRF52833 SoC, taking advantage of its 64MHz, 32-bit Arm® Cortex® M4 processor with floating point unit (FPU) and DSP instruction set to provide ample processing power, as well as the SoC’s Full Speed (12 Mbps) USB capability. USB enables low-latency and high-bandwidth communication with a range of host devices, and makes device firmware updates (DFU)-over-USB practical. 

The development boards, SDK and reference design cut our time to market by 30 to 40 percent
Mike Schell, Convergent Design

Additional features of the USB microphone include an ‘auto-mute’ function which mutes the audio when the user walks out of range, and automatically unmutes when they return. The addition of a USB hub provides the capability to use up to four microphones concurrently. A computer-based app supports firmware updates, the option to adjust the RF power level, volume control, and microphone mute/unmute functionality. It also reports the current microphone battery level as well as audio volume.

Erika employs a 75mAh Li-Poly battery that provides an industry-leading battery life of approximately 24 hours between recharge—depending on the configurable operating range—thanks in part to the ultra low power operating characteristics of the Nordic nRF52833 SoC. The nRF52833 enabled Convergent Design to create a wireless microphone ten times the power efficiency of competitive products, yet with 50 percent the size and weight of alternatives.

The nRF52833 combines the Arm M4 processor with a 2.4GHz multiprotocol radio (supporting 2.4GHz RF protocol software in addition to Bluetooth 5.2, Bluetooth mesh, Direction Finding, 2Mbps throughput, and Long Range plus Thread, Zigbee and IEEE 802.15.4 software) featuring +8dBm maximum TX power and -95dBm RX sensitivity. The SoC incorporates a generous amount of Flash (512kB) and RAM (128kB) memory and a range of analog and digital interfaces such as NFC-A, ADC, High-speed 32 MHz SPI, UART/SPI/TWI, PWM, I2S and PDM.

Superior radio sensitivity

“Many hardware and software factors led us to choose the nRF52833, including PDM microphone and USB support, which were both ‘must haves’ for our product,” says Mike Schell, President, Convergent Design. “The chip’s radio sensitivity and power consumption were critical features as they established our battery life and operating range, and without ESB as our starting platform the Erika wireless microphone would not exist."

“The development boards, SDK and reference design cut our time to market by 30 to 40 percent, while the technical support is second to none and really sets Nordic apart.”