The STEVAL-IKR002V4B evaluation daughterboard is based on the SPIRIT1, a sub-GHz low power, low data rate transceiver suitable for ISM bands and wireless M-BUS. The board is equipped with external balun, matching and filter in a single BALF-SPI-01D3 device which optimizes size, RF performances and number of external RF components (from 16 SMD passive components to just 1).

The SPIRIT1 is a very low-power RF transceiver, intended for RF wireless applications in the sub-1 GHz band. It is designed to operate both in the license-free ISM and SRD frequency bands at 169, 315, 433, 868, and 915 MHz, but can also be programmed to operate at other additional frequencies in the 300-348 MHz, 387-470 MHz, and 779-956 MHz bands.

The air data rate is programmable from 1 to 500 kbps, and the SPIRIT1 can be used in systems with channel spacing of 12.5/25 kHz, complying with the EN 300 220 standard. It uses a very small number of discrete external components and integrates a configurable baseband modem, which supports data management, modulation, and demodulation. The data management handles the data in the proprietary fully programmable packet format also allows the M-Bus standard compliance format (all performance classes).