Rainwalker OÜ
KIISU V4B
Carry a wallet-sized Flipper-firmware board for sub-GHz, NFC, RFID and infrared experiments.
Flipper-compatibleSub-GHzNFCRFID & NFCOpen hardware
Taking orders now; the maker sets the ship date.
Radio equipment needs certification where you live (FCC, CE, UKCA, ISED, Anatel). Some devices are uncertified or restricted in Brazil. Buyers are responsible for their local law.
- Bring along
- A microSD card, an LIR2032 cell (not CR2032) or USB power, and Flipper-compatible firmware.
- Keep in mind
- It lacks Flipper’s secret keys, so some sub-GHz protocols and U2F may not work, and it is sold as a development board rather than a finished product.
Image credit
Maker store photo: the KIISU V4B(R) development board · Rainwalker OÜ(02) Blueprint
What’s published
Rainwalker publishes a schematic PDF and 3D case models (STEP/STL) for the KIISU V4B under a strongly-reciprocal open-hardware license, but no KiCad/Altium/Gerber PCB-layout source or BOM is included.
KIISU V4B 3D model (STEP)
Read straight from the maker’s repository. Open on GitHub
Design files 5
Key parts 5
- STMicroelectronics STM32WB55RGAll STM32WB55 devicesMain MCU (Arm Cortex-M4, BLE + 802.15.4 radio)Datasheet
- STMicroelectronics STM32G431CBAuxiliary MCU (Arm Cortex-M4)Datasheet
- STMicroelectronics LSM303AGRAccelerometer/magnetometer (eCompass)Datasheet
- Bosch Sensortec BME680Gas/humidity/pressure/temperature sensorDatasheet
- GXCAS GXHTC3CTemperature/humidity sensorDatasheet
Research notes
Verified via `gh api repos/kiisu-io/kiisu4/git/trees/HEAD?recursive=1`: schematics PDF, STEP/STL 3D models and a previous 'v4a' schematics PDF are present; no .kicad_*/.sch/.brd/gerber/BOM files anywhere in the tree. Repo license is CERN-OHL-S-2.0 (strongly reciprocal), confirmed via the LICENSE file. STMicroelectronics' own st.com datasheet pages could not be reached from this environment (connection hangs, not a genuine 404) despite being the canonical URL for these exact part numbers -- LCSC-hosted mirror PDFs used instead and confirmed with 200 responses. GXHTC3C datasheet is shared with the base GXHTC3 part (same silicon family) per LCSC.
Every link checked 2026-09-27.
Hand this device to your agent. Everything on this page, as clean Markdown and JSON: specs, shops, prices, design files, parts.
Made the KIISU V4B? Put the badge on your README; it links here, with every shop that sells it.
Specifications
Cores and interfaces
5
Display, sensors and power
3
Firmware and compatibility
3
Buying and licence
3
No matching specification. Try a chip name, connector or feature.
What still needs checking
- The store shows prices in AED by default; the euro price is inferred from the base-currency figure and the AED presentment rate. Duties and taxes are the buyer’s responsibility.
- Board dimensions, weight, battery capacity and antenna performance are not quantified in the sources read.
- Radio emissions are the user’s responsibility to keep within local EMI rules; the maker calls it a development board for experienced users, not a consumer product.
