# Dash rheostat **URL:** \ **Category:** Feature requests\ **Created:** [September 15, 2019, 7:17pm UTC](https://forum.realdash.net/t/dash-rheostat/136 "2019-09-15T19:17:10Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![beplo](https://forum.realdash.net/user_avatar/forum.realdash.net/beplo/32/10_2.png) [@beplo](https://forum.realdash.net/u/beplo)\ **Post date:** [September 15, 2019, 7:17pm UTC](https://forum.realdash.net/t/dash-rheostat/136/1 "2019-09-15T19:17:10Z")
Hi, is it possible to add a rheostat to reduce the intensity of light at night? It would be nice if it can be set at this time of day. ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [September 16, 2019, 6:19am UTC](https://forum.realdash.net/t/dash-rheostat/136/2 "2019-09-16T06:19:01Z")
In theory yes. You could read the sensor and use actions to change the screen brightness accordingly. If you are running on phone or table, I think best is just use devices own automatic brightness setting. ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [November 20, 2020, 12:36pm UTC](https://forum.realdash.net/t/dash-rheostat/136/3 "2020-11-20T12:36:46Z")
Would it be possible to give an example or tutorial on how to make Realdash do this? My embedded SBC does not have an automatic dimmer, but I can send the value of the car’s brightness setting to Realdash via an attached arduino. ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [November 20, 2020, 12:53pm UTC](https://forum.realdash.net/t/dash-rheostat/136/4 "2020-11-20T12:53:00Z")
RealDash is probably unable to adjust the screen brightness when running on a SBC with external screen. In Android there is an API to adjust screen brightness, but I have not seen it work in anything but devices with built-in screen. ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [November 20, 2020, 2:37pm UTC](https://forum.realdash.net/t/dash-rheostat/136/5 "2020-11-20T14:37:23Z")
OK, I can understand that and why. Thanks! ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [November 20, 2020, 5:55pm UTC](https://forum.realdash.net/t/dash-rheostat/136/6 "2020-11-20T17:55:00Z")
If you use an external dimming device, you can force RealDash to control that device via the RDCan protocol! For example Arduino 😉 ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [November 20, 2020, 6:04pm UTC](https://forum.realdash.net/t/dash-rheostat/136/7 "2020-11-20T18:04:26Z")
Is this how you have yours setup? IIRC, you are using a VIM2. I am using a VIM3. Are you just controlling voltage to the LED inverter? ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [November 20, 2020, 10:58pm UTC](https://forum.realdash.net/t/dash-rheostat/136/8 "2020-11-20T22:58:07Z")
Well yes! ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [November 21, 2020, 12:29am UTC](https://forum.realdash.net/t/dash-rheostat/136/9 "2020-11-21T00:29:37Z")
Very awesome! Care to share any details? I have some ideas, but always better to ask someone who has already solved the problems. ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [November 21, 2020, 5:08am UTC](https://forum.realdash.net/t/dash-rheostat/136/10 "2020-11-21T05:08:03Z")
I think that for each case the solution will be purely individual! My board is assembled and functioning! And I, as its author, do not really want to share the iron component! But there is nothing difficult in this and you will quickly find a way out, as you are on the right track! I am using a stepper motor driver to turn the LED on and off smoothly ---
**Author:** ![Tarekastra](https://forum.realdash.net/letter_avatar_proxy/v4/letter/t/bb73d2/32.png) [@Tarekastra](https://forum.realdash.net/u/Tarekastra)\ **Post date:** [January 24, 2021, 7:40pm UTC](https://forum.realdash.net/t/dash-rheostat/136/11 "2021-01-24T19:40:26Z")
Jani, I set a trigger with an action to set the brightness, i use change value with range from 0 to 1 and step 1. When trigger happened the display dimmed and didn’t return back to normal brightness level. I need to know how to set the brightness and brightness range. ( I am using single board computer) Regards ---
**Author:** ![realdashdev](https://forum.realdash.net/user_avatar/forum.realdash.net/realdashdev/32/6_2.png) [@realdashdev](https://forum.realdash.net/u/realdashdev)\ **Post date:** [January 25, 2021, 6:46am UTC](https://forum.realdash.net/t/dash-rheostat/136/12 "2021-01-25T06:46:58Z")
Brightness is in range 0-100%. ---
**Author:** ![Tarekastra](https://forum.realdash.net/letter_avatar_proxy/v4/letter/t/bb73d2/32.png) [@Tarekastra](https://forum.realdash.net/u/Tarekastra)\ **Post date:** [January 26, 2021, 7:53pm UTC](https://forum.realdash.net/t/dash-rheostat/136/13 "2021-01-26T19:53:04Z")
It works for me, i made a trigger based on parking light and action will be set value= 0 (at night) when parking light is ON, and 100 when parking light is Off (at Day). Thanks ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [January 27, 2021, 5:58pm UTC](https://forum.realdash.net/t/dash-rheostat/136/14 "2021-01-27T17:58:30Z")
So I handled this in hardware for my application. The first thing is that most external LCD displays that you would use in this type of application will have an LED backlight, with a separate LED driver/inverter. On all of the ones I have here, there is an input pin on that driver for brightness, usually labeled ADJ. It will have a wire going to it, straight to ground (if you test it out). This gives maximum brightness. Bringing that pin to +3.3v will drive the LED backlight to the minimum brightness level it is setup for. I used an Arduino to read the original dash lighting potentiometer, which was setup for 0-5v via an analog input pin. At the same time, I setup a PWM pin to go from 0-100% duty cycle at 2kHz. Some math, a little code, and voila! It works great! I imagine you can use 2-Way CAN from RD to drive an external Arduino, and handle the PWM that way, too. ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [January 28, 2021, 6:34pm UTC](https://forum.realdash.net/t/dash-rheostat/136/15 "2021-01-28T18:34:25Z")
I think it’s real! ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [January 28, 2021, 6:37pm UTC](https://forum.realdash.net/t/dash-rheostat/136/16 "2021-01-28T18:37:05Z")
> [@](#): > > I used an Arduino to read the original dash lighting potentiometer, which was setup for 0-5v via an analog input pin. At the same time, I setup a PWM pin to go from 0-100% duty cycle at 2kHz. How did you physically connect ADJ and Arduino? Directly or through a transistor? ---
**Author:** ![nemiro](https://forum.realdash.net/letter_avatar_proxy/v4/letter/n/d2c977/32.png) [@nemiro](https://forum.realdash.net/u/nemiro)\ **Post date:** [January 28, 2021, 7:22pm UTC](https://forum.realdash.net/t/dash-rheostat/136/17 "2021-01-28T19:22:45Z")
I ran mine directly. It seems to work just fine. ---
**Author:** ![CoTECH](https://forum.realdash.net/user_avatar/forum.realdash.net/cotech/32/8_2.png) [@CoTECH](https://forum.realdash.net/u/CoTECH)\ **Post date:** [January 30, 2021, 5:18pm UTC](https://forum.realdash.net/t/dash-rheostat/136/18 "2021-01-30T17:18:57Z")
> [@](#): > > I ran mine directly. It seems to work just fine. this is great news! ---
**Author:** ![smwoodward](https://forum.realdash.net/letter_avatar_proxy/v4/letter/s/a587f6/32.png) [@smwoodward](https://forum.realdash.net/u/smwoodward)\ **Post date:** [October 18, 2022, 5:56pm UTC](https://forum.realdash.net/t/dash-rheostat/136/19 "2022-10-18T17:56:10Z")
> [@KGTM](#): > > In theory yes. You could read the sensor and use actions to change the screen brightness accordingly. If you are running on phone or table, I think best is just use devices own automatic brightness setting. The setup I am developing has the LCD directly attached to the SBC which gives me control of the brightness through Android. My question is what action would be used to adjust the brightness in android? ---
**Author:** ![smwoodward](https://forum.realdash.net/letter_avatar_proxy/v4/letter/s/a587f6/32.png) [@smwoodward](https://forum.realdash.net/u/smwoodward)\ **Post date:** [October 19, 2022, 12:02pm UTC](https://forum.realdash.net/t/dash-rheostat/136/20 "2022-10-19T12:02:48Z")
Does RealDash have the capability of requesting the android OS to adjust the screen brightness? [Next page](https://forum.realdash.net/t/dash-rheostat/136.md?page=2)