KROT_STM – F1
A continuation of the Krot MD line, using a modern 32-bit microcontroller from the STM32F103 series. The device is based on the KROT PRO MD firmware and case, and therefore has a similar menu and controls. It now features a single frequency range of 8-17 kHz, as well as the previous 88-101 MHz FM transmitter.
Scheme (ed. 12/24/22) from “TSV”.
Pay particular attention to the quality of the capacitors marked in green, CB5 film! The indicator is a COG 12864G-086-P, 3.3 V. The indicator controller is a UC1701X.
You can order boards ( To make PCB ) v_03 at this link. Register on the PCBWay website.
Solder approximately like this:
Registration on the PCBWey website ****** Link to order PCB,
The coils are the same as in The Krot2“. With the use of a more powerful controller, the coil requirements have been slightly reduced. The following cable wiring is suggested for the coil connector: 1) RX+ 2) RX- 3) GND 4) TX+ 5) TX-
How to make a coil
Firmware “Krot-STM-F1” from 09.02.2024 NEW
Initially, the firmware operates in demo mode with some limitations and becomes fully functional after entering the key. Please note: the number of attempts is limited to five. The key is a one-time, permanent installation. Firmware can be updated. Each device has its own unique key, and it remains unchanged. For any questions regarding keys, please PM or email: radiodom@i.ua
“KROT STM_F3” based on the STM32F303C8T6 controller
Increased speed and sensitivity, smooth current adjustment (0-10), a new sound, and an auto-balance coil mode. Operating frequency range: 7-20 kHz.
Firmware “Krot-STM_F3B” for STM32F303CBT6 from 01.05.2024 With this controller, everything is the same as with the STM32F303C8T6 , but the autobalance does not work.
Firmware Krot STM_F45 for STM32F303C8T6 from 11.05.2024 Firmware with operating frequencies of 6-45 kHz requires frequency response correction for more correct operation
Firmware Mole STM_F3d for STM32F303C8T6 from July 31, 2026 NEW
Firmware Krot STM For STM32F303CBT6 from 05/12/2026 Firmware with operating frequencies of 6-26 kHz. Increased sensitivity and added a “Deep Sounder” mode. New sound schemes. New “DISC” modes.
Firmware Mole STM_F3D for STM32F303C8T6 from March 24, 2026. Firmware with operating frequencies of 6-15 kHz. The device’s sensitivity has been increased and a “Deep Diver” mode has been added. Video of the operation . NEW
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“KROT STM_H7” based on the STM32H750VBT6 controller
Slightly increased sensitivity and response speed, new sound modes, and other improvements. Operating frequency range: 6-25 kHz.
Circuit diagram (Thanks to “Odyssey87” for help!)
Firmware “Krot-STM_H7” from May 14, 2025. “GBV/GBF” mode (factory settings). Selecting the ground balance method. GBV – Vector, GBF – Phase. Other improvements to improve search performance.
Krot STM_H7D firmware from March 17, 2026. Firmware with operating frequencies of 4-15 kHz. The device’s sensitivity has been increased and a “Deep Diver” mode has been added. Video of the new device in operation.
Firmware “Krot-STM_F3” for STM32F303C8T6 from 03/27/2025 . “GBV/GBF” mode (factory settings). Selecting the ground balance method. GBV – Vector. GBF – Phase. The frequency range has been expanded from 7 to 20 kHz. Other improvements improve search qualities. “VOL.SHEMS” mode – Sound scheme. 1 – “bell”. 2 – normal sound + “bell” for a high rating. 3. Normal sound. Weak signal volume control mode “Vol.W.Sig” range 0-5.
The programming software
To program microcontrollers, you can use the ST-LINK programmer . There are also other programming methods, such as RS232 or USB (search the internet).