I am trying to drive a 350 watt, 3 phase, BLDC motor (DGW07-20j model) with STM32 micro controller. But I have problem with Hall sensors because their outputs are not similar to the Hall sensors which I have seen on the internet.

hall sensor on oscob I connected the sensor supply to +5V DC (according to the sensor PCB guide). Then I connected two of Hall sensor outputs (2 of 3) to the oscilloscope channels which is shown in the following picture.

motor  pcb Unfortunately, I couldn't find the model number of Hall sensor or related data-sheet. But I connected the supply and outputs based on printed pinout guide on PCB. You can see these connections in this picture... The motor was working while I captured the hall sensor outputs but clearly not not in a good way because the switching phase timing should be adjusted using hall sensor outputs.

many thanks

other timming hall sensor on oscob


1 Answer 1


After three days hard working for this problem I found the answer! By adding an RC filter on each hall output I see the right signal.

https://i.stack.imgur.com/yXvEg.jpg enter image description here

  • \$\begingroup\$ I find this accepted answer highly misleading. First of all what's shown on the schematic aren't RC filters to the hall signals. And the root cause was most likely the hall sensors having open drain/collector outputs. So R29, R30 and R31 probably solved the problem by acting as pull-up resistors. \$\endgroup\$
    – feynman
    Nov 5, 2022 at 11:02

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