KUdos Magnetic Encoder

Project Overview

This is a custom magnetic encoder board I designed for the KUdos VEX-U robot odometry system. The board uses an AS5047P magnetic rotary position sensor configured for quadrature output, providing high-resolution position feedback for the Pinpoint odometry computer.

Role: PCB designer

Tools: KiCad, JLCPCB

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Why Custom Encoders?

The goBILDA Pinpoint odometry computer expects standard quadrature encoder inputs. Rather than using off-the-shelf optical encoders, we designed a magnetic encoder that:

• Has no moving parts to wear out
• Is immune to dust and debris
• Provides 4096 counts per revolution (14-bit resolution)
• Works with any shaft that can hold a diametric magnet

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Schematic

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Design Details

AS5047P Configuration

The AS5047P-ATSM is a 14-bit magnetic rotary position sensor from AMS. It supports multiple output modes:

• SPI (digital)
• ABI (quadrature encoder)
• UVW (brushless motor commutation)
• PWM

For this design, we use ABI mode (quadrature output) by disabling SPI:

Pin	Connection	Purpose
CSn	Pulled high (10k to VIN)	Disable SPI mode
CLK, MISO, MOSI	Pulled low (10k to GND)	Disable SPI interface
TEST	GND	Normal operation
A, B	Output connector	Quadrature signals

With SPI disabled, the chip automatically outputs quadrature on the A/B pins.

Output Connector

4-pin connector (J1) with standard encoder pinout:

Pin	Signal
1	GND
2	VIN (3.3-5V)
3	A (quadrature channel)
4	B (quadrature channel)

This matches the Pinpoint's encoder input format.

Power

• VIN: 3.3V to 5V input
• C1: 100nF decoupling capacitor
• Current draw: ~10mA typical

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Resolution

The AS5047P provides:

• 14-bit absolute position (16,384 positions per revolution)
• Quadrature output: 4096 pulses per revolution (1024 CPR x4 quadrature)

With the small omni wheels on the odometry pods, this gives sub-millimeter position resolution.

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Assembly

The board is designed for easy assembly:

• Single-sided SMD components
• 0603 resistors (hand-solderable)
• AS5047P in TSSOP-14 package
• Diametric magnet mounted on shaft above the chip

The magnet must be centered over the chip with ~1mm air gap for optimal performance.

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Tech Stack

Area	Tools
Schematic & Layout	KiCad
Fabrication	JLCPCB
Sensor IC	AS5047P-ATSM