Add Brightness Slider or buttons

[makerplane-jnicol]

We will need to add in a brightness control for specific control of the GPIO PWM for the Pi. I know we have also discussed a global brightness control that will dim or brighten the whole panel. Right now we cannot control the brightness of the display from within pyEfis.

Code supplied by Steve to control this follows. Also suggest that it does not dim to 0 as that would be a black screen. Come up to 10 so that the screen can still be seen and not confused with an off screen:

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
GPIO.setup(18, GPIO.OUT)
pwm=GPIO.PWM(18, 100)
pwm.start(0)

for dc in range(0,110,10):
        print dc
        pwm.ChangeDutyCycle(100-dc)
        time.sleep(1)

pwm.stop()
GPIO.cleanup()

I think that there are two options potentially.

1. Add a function that can be called from main.yaml to add buttons that increase or decrease brightness similar in function to the BARO +, BARO -. It would be great if the brightness value could be superimposed onto the display in a corner so that the user knows the brightness of the display so that you don't press multiple times to figure out if you are at max brightness. That is annoying.
2. Create an instrument that is a slider object that can be placed onto a screen.

[e100]

The UI portion of this would be easy to setup with just configuration by using a vertical or horizontal bar gauge with an 'up' and 'down' transparent button on top of the gauge.

We would need a plugin in fix gateway that would set the screen brightness based on the value changed by the buttons.

[birkelbach]

There is a "dimmer" plugin for FiXGateway. It writes to a Linux device file that sets the screen brightness. The MakerPlane 5 in display may not play nice with the Linux driver and therefore needs the above code. I'm not sure. I'll try to find some time to play with it.

[e100]

I created an example dimmer control and submitted a pull request #189
To add this to a screen one would just need to include this control on their screen definition, this can be done like:

  - type: include,includes/vertical_dimmer_control.yaml
    row: 90
    column: 16
    span:
      rows: 20
      columns: 6

I did not merge the pull request because this also requires adding some new fixids to the fixgateway and without some mechanism to auto-update default configuration files this could be a breaking change for some users.
I created #190 to discuss how to deal with the config files