Actions
Forum Thread Details
  • Replies 3 replies
  • Subscribers 392 subscribers
  • Views 330 views
  • Users 0 members are here
Related

Reading state of a powered button.

Former Member

Hey guys, Having a bit of trouble figuring out the best way to read the state of my brake lever on my Electric Bike. The bike is 48V, and the high side of the button embedded in the lever has the full 48V running through it. It needs to remain connected to the main controller of the bike so that it can activate the electric assisted braking.  i would like to be able to read the state of this button with a 5V arduino, without disconnecting it from 48V (basically monitor it for changes at the same time as the original controller, neither it or the arduino being affected by the other (no load on the 48V as that would trigger the button state as far as the main controller (and my brake assist haha) ) ) . I have one idea, but i would like to hear what the community can come up with, as i feel my idea is highly inefficient.

 

 

edit: my original idea is to just cut the switch away from the main controller, read the state with arduino, and if high (or low can't remember which way the switch is at the moment), trigger a MOSFET on the LED and either another MOSFET or a relay across where the controller expects the switch

 

excuse my horrible explanations haha i'm really tired, it's been really busy around here

 

Edit: i actually just figured it out, i explained this horribly, sorry guys i'm tired and it's 5AM here. keep an eye on my other post, i'll explain in a few days with a video, as i just realized i'll have to go back to the start on this bike.

Other post: My new Electronics Blog

  • Hello Zakk

    If you only need to check the state of the button and no more...

     

    517edbabce395fd51d000000.png

     

    You only need to connect one circuit (48v) at 1P and other circuit (5V) to 2P

    I hope to have understood what you are asking.

  • Zakk,  The safest way to monitor your braking control so as not to compromise the braking or risk the Arduino getting fried is to use ab opto isolated input to the Arduino.  Presumably the voltage on the brake changes from 0 to 48 volts so if you monitor the voltage via a suitable resistor to drive the internal LED in the opto  isolator then you will achieve your goal.  Choose a suitable opto isolator that you either have or can get locally, check its specs and then use ohms law to calculate the required resistor.  For example if the internal led needs say 10 mA and has a forward volt drop of 1.8 v then you need to use a voltage of (48 - 1.8 volts) and a current of 10 mA.

    On the Arduino input you can use the internal pull up resistor to pull the input hi, then use the output of the opto isolator to pull the input low via a suitable current limiting resistor, something like 2.2 K should work.  You could use the input to trigger an interrupt if you so desired.

     

    A simple way to test if you are monitoring the brake voltage is just to rig up an ordinary LED to the brake and see if you can get it to turn on / off without the Arduino.  Method to work out current limiting resistor is the same.

     

    I hope that helps.  I haven't done all the work for you as I believe doing a little research helps the learing process immensely.

  • edited. Thanks, though, always appreciate quick responses image