The latest wave of IoT devices creates a massive demand for data exchange with bandwidth requirements much higher than before. To achieve high data rates in wireless communication, a wideband receiver is critical. The STEVAL-ISA170V1 is a cost-effective, high-performance, and flexible platform that enables rapid development of wideband receiver systems operating from 100 kHz to 1 GHz. In this article, we cover everything you need to know about the STEVAL-ISA170V1 to implement a successful wideband receiver for IoT applications.

Understanding the STEVAL-ISA170V1

The STEVAL-ISA170V1 features an RF front-end composed of a dual operational amplifier to shape the input impedance, and a dual-channel down-converter with selectable front-end filters. The low-level signals come through two parallel channels down to two separate analog-to-digital converters (ADCs) that convert the signals to digital format.

The platform's main components are an STM32F446ZE microcontroller, which acts as a bridge between the front-end and a host PC, and an SPI flash memory to store the firmware. The STM32F446ZE includes a Cortex-M4 core with hardware floating point unit and DSP instructions, 512KB flash and 128KB SRAM, and all the connectivity peripherals required to communicate with external devices.

Designing a Wideband Receiver with the STEVAL-ISA170V1

The STEVAL-ISA170V1 board can be used directly as a front-end module with a simple data acquisition (DAQ) system, such as a USB dongle, PC sound card, or single-board computer (SBC). Figure 1 shows the block diagram of a basic STEVAL-ISA170V1-based receiver system.


The principle of a wideband receiver is to sample the signals at a rate greater than or equal to the Nyquist frequency, which is two times the highest frequency component of the signal. Therefore, the STEVAL-ISA170V1 ADCs' sampling rate limit is an essential parameter to design a proper wideband receiver.

The ADCs can operate at sampling rates from 50 kSamples/s to 64 MSamples/s with a resolution of 14 bits. The ADCs' front-end filters can select a bandwidth range of 100 kHz to 5 MHz that are widely adjustable according to the signal's characteristics. The STEVAL-ISA170V1 also supports the external clock synchronization of the ADCs using a dedicated connector.

The RF front-end requires careful impedance matching for proper functionality, requiring RF transformers and attenuators to keep the signal amplitude within the ADCs' input voltage range. The STEVAL-ISA170V1 includes several I/O and debug connectors that allow detailed signal measurement and tuning of the analog front-end.

Software Development with the STEVAL-ISA170V1

The STEVAL-ISA170V1 firmware development is based on the STM32Cube software framework and the System Workbench for STM32 IDE. The firmware includes several layers of software components, like system initialization, drivers for ADCs, USART communication, SPI flash memory, and hardware abstraction layer (HAL).

The firmware must configure the system clock, the TIM3 timer for ADC synchronization, and the USART1 interface at 921600 baud for communication with the host PC. The firmware must also implement the command protocol that allows the remote control of the STEVAL-ISA170V1 over the USART1, enabling the selection of ADC sampling rate, front-end filter bandwidth, and other parameters.

Once the firmware is uploaded to the SPI flash memory, the STEVAL-ISA170V1 can be used as a standalone module, but a host PC is recommended to receive and display the samples. Several software options are available to display and process the samples in real time, like GNU Radio, SDR, RTL-SDR, HDSDR, and others.

Applications of the STEVAL-ISA170V1

The STEVAL-ISA170V1 is an ideal platform to develop new IoT applications, like wireless sensor nodes, environmental monitoring, energy metering, and medical wearables. The wideband receiver capability can also be used to receive FM radio, digital audio broadcasting (DAB), low earth orbit (LEO) satellite telemetry, and terrestrial trunked radio (TETRA) signals.

In summary, the STVEAL-ISA170V1 is a valuable platform to implement wideband receiver functionalities for IoT and beyond. Its low cost, high performance, and flexibility make it a preferred option for hobbyists, students, and professionals alike. With a comprehensive understanding of its capabilities and configuration, the STEVAL-ISA170V1 can be an excellent addition to any RF enthusiast's kit.

\[1] STEVAL-ISA170V1 Product Page. [STMicroelectronics](https://www.st.com/en/evaluation-tools/steval-isa170v1.html)

\[2] STM32Cube Overview. [STMicroelectronics](https://www.st.com/en/embedded-software/stm32cube-mcu-packages.html)

\[3] System Workbench for STM32 Downloads. [OpenSTM32](https://www.openstm32.org/System%2BWorkbench%2Bfor%2BSTM32)

\[4] RTL-SDR Downloads. [rtl-sdr.com](https://www.rtl-sdr.com/software-windows/)