Magnetic (Hall Effect) Noise-free End Stops / Homing Sensors – Part 1

After reading some the Shapeoko community’s experience with mechanical end-stops, I decided to design my own hall-effect based sensor solution. I’m not saying I went about it the right way and there are probably better/cheaper/faster solutions, but it’s what I came up with. I should say, I was inspired by Kevin Patterson’s hall effect solution (love the red/green feedback LEDs.)  https://www.youtube.com/watch?v=vqU_5wZAX3s6

NOTE: This design has not been implemented yet. Still waiting for one more board from OshPark to arrive.

Features:
* 24V separate power supply for the hall effect circuit.
* Nominally high (active low) design.
* Opto-isolated sensors
* Higher sensor voltage (24V) in combination with some simple pull-ups an caps to help ride out any coupled transients.

I’ve built some acrylic holders for the sensor boards and a small enclosure for the main board. The concept is similar to Kevin’s in that I will have 6 sensors (2 for each axis) connected with inexpensive phone cord connected by RJ11’s to the main board. I’ll mount my main board to the side of my control box where the grblshield/arduino lives.

Enclosure made with the Shapeoko. Holds spindle power supply, Arduino, grill-shield, and speed controller.
Enclosure made with the Shapeoko. Holds spindle power supply, Arduino, grbl-shield, and speed controller.

The PCBs are available to purchase or download the gerber files (PCB build files needed by a board house to make printed circuit boards) from Oshpark.com.
Main Board: https://oshpark.com/shared_projects/RHwVNxOU1
Sensor Board: https://oshpark.com/shared_projects/B7TXAfxt2

FYI:
Schematics and PCB Layout software –> OrCad
Housing design: ViaCad + MeshCam

SCHEMATICS:

shapeoko_homing_circuit_sensor_board

shapeoko_homing_circuit_main_board

BOM: (Note: I recommend the DRV5023AJQDBZR for the Hall Sensor instead of what’s on the BOM. The one in the BOM is a latching version and shouldn’t be used.  Use Digikey PN: 296-38452-1-ND)

Digikey_Order_Shapeoko_homing_circuit

1 of 6 sensors inside an acrylic housing (unpopulated)
1 of 6 sensors inside an acrylic housing (unpopulated)
Main board housing and Sensor covers.
Main board housing and Sensor covers.
Original batch of PCBs from OshPark.
Original batch of PCBs from OshPark.
Testing the sensor circuit before the boards showed up.
Testing the sensor circuit before the boards showed up.
Getting some of the parts ready for the build including a little shield board to solder on the sensor inputs to the UNO.
Getting some of the parts ready for the build including a little shield board to solder on the sensor inputs to the Arduino Uno.

As I build and test this concept I’ll try to post my results. Hope this helps some of you.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>