How to control a hall effect joystick with a micro.

Thread Starter

Philledger

Joined Dec 29, 2016
6
We have a fine old (OLD) powered scooter we wish to transform into a awesome robot!
The wheelchair is factory controlled by a hall effect joystick. We want to bypass the joystick (hopefully with out disconnecting it) and control it with a micro. Understand a DAC is what we need. Saw this problem solved on line years ago but can't find the link!
Any help would be appreciated!
Thanks, Phil
 

Alec_t

Joined Sep 17, 2013
11,896
Welcome to AAC.
Do you have a link to the joystick specification/wiring? Without knowledge of the joystick's parameters and wheelchair wiring it may not be possible to do what you want without risk of damage.
 

Thread Starter

Philledger

Joined Dec 29, 2016
6
Perhaps ten years ago I started this project and posted this question.
One of your members sent me the parts and a PCB free of charge!
If i remember correctly, ya'll helped me track down the schematics to the scooter and we had a good idea of how this thing worked.
I don't suppose it's possible to find that old thread so we will, as time permits, get some numbers off the machine and get back to you later.
 

Thread Starter

Philledger

Joined Dec 29, 2016
6
The hall effect joystick on my scooter has 3 wires, a red 5 volt, a black ground, and a green control wire.
The control wire changes from +.8 volts = 0% throttle up to +3.8 volts = 100% throttle.
 

MaxHeadRoom

Joined Jul 18, 2013
22,379
Does that mean it increases on a linear fashion from .8 to 3.8?
If so any small micro system, Pic etc, have A to D inputs that can be used.
Max.
 

djsfantasi

Joined Apr 11, 2010
7,402
I've never done this before, but what comes to mind is that you need the opposite of the previously mentioned ADC. It's an DAC. Digital to Analog Converter.

Adafruit has one that connects to your microcontroller via I2C There are others.

This site also discusses R/2R ladder DAC circuits.

Guys? Can you add to this?
 

Alec_t

Joined Sep 17, 2013
11,896
You could use a PWM output of the micro, feeding a low-pass filter to get the required analogue voltage which the scooter is expecting.
 

Thread Starter

Philledger

Joined Dec 29, 2016
6
Here is the mentioned DAC....
MCP4725 Breakout Board - 12-Bit DAC w/I2C Interface
PRODUCT ID: 935
$4.95
You could use a PWM output of the micro, feeding a low-pass filter to get the required analogue voltage which the scooter is expecting.[/QUOTE]

Wonder if the micro will be overloaded using PWM?.
We could check the amperage going through the joystick.
Well thanks for all your input!
You've certainly given me some good ideas on how to proceed.:)
 
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