On July 30, 2026, Novosense released the NSM350x series — China’s first Hall-effect-based dual-track vernier magnetic encoder IC. The launch sent a clear signal through the robotics joint module and encoder engineering community: there is now a domestic alternative to iC-Haus’s iC-MU platform, and it uses the same Nonius/Vernier encoding principle, the same pole-pitch options, and the same off-axis mechanical architecture.

This article breaks down the NSM350x from four angles: sensing architecture, performance specifications, calibration strategy, and magnetic ring requirements — with a practical assessment of how the chip fits into real-world robot joint designs.

1. Sensing Architecture: Differential Hall + Dual-Track Vernier

The NSM350x uses a differential Hall sensing front-end coupled with a dual-track vernier algorithm. An integrated Hall array senses the perpendicular magnetic field from a dual-track encoder ring. The ring carries two concentric magnetic tracks — a Master track and a Nonius track — with pole-pair counts that differ by one (e.g., 32/31 or 64/63). The phase difference between the two tracks encodes a unique absolute angular position over one full revolution.

This is precisely the same Nonius/Vernier principle used in the iC-Haus iC-MU family. The chip reads both tracks simultaneously, computes the phase offset, and synthesizes the absolute mechanical angle — no batteries, no homing routine, no incremental counter to lose on power-down.

The differential architecture provides common-mode rejection of external stray magnetic fields. In a robot joint packed with motor windings, this matters. Differential sensing cancels interference that a single-ended Hall chain would pass through to the interpolator. No external magnetic shielding is required under normal operating conditions.

Signal Chain

Hall Array → Analog Front-End (amplify, filter) → ADC → DSP (offset calibration, gain matching, temperature compensation, vernier synthesis) → Output Interface

Model Variants & Magnetic Ring Compatibility

All three variants share identical pole-width specifications with the iC-Haus iC-MU family. The magnetic ring geometry is mechanically interchangeable between the two platforms — swap the PCB, keep the ring.

2. Performance Specifications

Two differences that matter for system design: (1) iC-Haus has BiSS-C and SSI — the industrial servo protocol standard. If your drive requires BiSS-C, iC-MU is the only option today. (2) NSM350x carries AEC-Q100 and supports 3V operation — relevant for battery-powered mobile robots and automotive applications.

3. Four-Tier Calibration Architecture

The standout feature of the NSM350x is its four-layer progressive calibration system. Calibration parameters are stored in on-chip EEPROM and loaded automatically at power-up. Calibration status is readable via PWM output or the SPI CAL_STATE register.

4. Off-Axis Installation: Mechanical Design Notes

The NSM350x is designed for off-axis mounting — the sensor IC sits beside the magnetic ring, not above the shaft center. The ring’s entire center bore remains clear for cable routing — exactly what hollow-shaft robot joints need.

• Chip-to-ring gap: NSM3502 is specified for a 2.0 mm pole width. The air gap must remain stable across the full rotation; gap variation directly degrades INL.
• Concentricity: Keep the ring’s center-to-axis eccentricity below 0.05 mm. Eccentricity causes periodic field amplitude modulation that confuses the vernier algorithm.
• External field tolerance: <0.5 mT — no effect. 0.5–1 mT — possible accuracy loss. >1 mT — potential functional failure.
• Ring orientation: The dual-track side faces the chip. Installing the ring upside-down means the chip sees the wrong magnetic pattern.

5. Interchangeability with iC-Haus iC-MU

The NSM350x and iC-Haus iC-MU share identical pole-width specs (1.28/1.50/2.00 mm) and the same dual-track Nonius encoding principle. A single dual-track magnetic ring works with either chip platform — swap the readhead PCB, keep the mechanical design. iC-Haus brings BiSS-C/SSI industrial protocol maturity; Novosense brings AEC-Q100 and on-chip calibration. Different applications, different trade-offs, same ring.

OTV Sensing: Dual-Track Magnetic Ring Solutions for Both Platforms

Regardless of which chip you choose, the encoder system’s final accuracy is determined by the quality of the magnetic ring. Pole-width precision, field uniformity, and material thermal stability set the ceiling on what any calibration routine can achieve.

OTV Sensing provides dual-track encoder rings for both the Novosense NSM350x and iC-Haus iC-MU platforms:

References: Novosense NSM350x product documentation, iC-Haus iC-MU datasheet, Elecfans NSM3502 technical review. NSM350x series launched July 30, 2026. NSM3502 (2.0 mm pole width) samples available now.