Jan 27, 2026

US12535283 - Determination of round count by hall switch encoding

This disclosure describes systems, methods, and apparatus for detecting and displaying a number of rounds in a firearm magazine comprising a maximum number of N rounds. The magazine may comprise a follower, magnets on the follower, and <N magnetic-field-sensing sensors arranged along a path of the magnets when the follower moves along a length of the magazine, the sensors generating round count data based on a position of the one or more magnets relative to the <N magnetic-field-sensing sensors, and a first substantially flat antenna arranged on an inside of the magazine and configured to wirelessly transmit a round count indication to a second substantially flat antenna on the firearm, the round count indication based on the round count data, the second substantially flat antenna affixed to an inside of a magazine well of the firearm and mostly overlapping with the first substantially flat antenna.

Assignee: Magpul Industries Corp.
Inventors: Erin Czarnecki, Jeffrey Holt, Michael Leighton, Donald McKelvey, Steven Dunbar, Timothy Eric Roberts, Nicholas Kielsmeier, Eric Chow
Filing date: 2023-06-16

firearmmagazineroundcount

This patent describes a system for tracking the number of rounds in a firearm magazine using magnetic-field-sensing sensors and a microcontroller unit (MCU) that computes the round count based on the position of magnets on the magazine follower. The system also includes wireless communication between antennas in the magazine and firearm to display the round count information.

Claim 1

1 . A method of round count communications for a firearm, the method comprising: sensing movement of a firearm magazine with an accelerometer; initializing a microcontroller unit (MCU) in response to the sensed movement; activating at least a first magnetic-field-sensing sensor of a plurality of magnetic-field-sensing sensors arranged substantially along an inside of the magazine; receiving a signal from the first magnetic-field-sensing sensor in response to a magnet being proximate the first magnetic-field-sensing sensor; determining a location of the magnet within the magazine based on a location of the first magnetic-field-sensing sensor; deactivating at least one second magnetic-field-sensing sensor of the plurality of magnetic-field-sensing sensors; and using the MCU to compute a round count from the location of the first magnetic-field-sensing sensor. sensing movement of a firearm magazine with an accelerometer; initializing a microcontroller unit (MCU) in response to the sensed movement; activating at least a first magnetic-field-sensing sensor of a plurality of magnetic-field-sensing sensors arranged substantially along an inside of the magazine; receiving a signal from the first magnetic-field-sensing sensor in response to a magnet being proximate the first magnetic-field-sensing sensor; determining a location of the magnet within the magazine based on a location of the first magnetic-field-sensing sensor; deactivating at least one second magnetic-field-sensing sensor of the plurality of magnetic-field-sensing sensors; and using the MCU to compute a round count from the location of the first magnetic-field-sensing sensor.

Google Patents

https://patents.google.com/patent/US12535283

USPTO PDF

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/12535283