Difference between revisions of "Example brightness"
m (Added useful information and marked FinalDraft.) |
|||
| Line 1: | Line 1: | ||
| − | {{todo|InProgress(12.27.13-11:41->JG+)|Jgreene|project=oe 4,oe 5,jg,md, | + | {{todo|InProgress(12.27.13-11:41->JG+);(12.30.13-16:55->MD+)|Jgreene|project=oe 4,oe 5,jg,md,FinalDraft}} |
This is a guide to the <code>brightness</code> C example project included in the EMAC OE SDK. | This is a guide to the <code>brightness</code> C example project included in the EMAC OE SDK. | ||
| − | This is a simple backlight | + | This is a simple backlight brightness control. It's written for the EMAC PPC-E7 and SoM-9307 but it will probably run on anything with a backlight. It implements a slider application in GTK+ that directly controls the backlight through its sysfs interface. It has been tested under Xfbdev/Matchbox. |
The <code>brightness</code> project builds one executable: <code>brightness</code>. | The <code>brightness</code> project builds one executable: <code>brightness</code>. | ||
| Line 26: | Line 26: | ||
==Usage and Behavior== | ==Usage and Behavior== | ||
| − | The <code>brightness</code> C example project creates a GTK+ UI for controlling the backlight | + | The <code>brightness</code> C example project creates a GTK+ UI for controlling the backlight brightness. It gives us a slider, a spinner and a textfield. |
===Hardware Requirements=== | ===Hardware Requirements=== | ||
| Line 34: | Line 34: | ||
===Using <code>brightness</code>=== | ===Using <code>brightness</code>=== | ||
| − | From the terminal, first set the DISPLAY variable | + | From the terminal, first set the DISPLAY variable: |
export DISPLAY=:0.0 | export DISPLAY=:0.0 | ||
| − | Then run the <code>brightness</code> C executable | + | Then run the <code>brightness</code> C executable: |
./brightness | ./brightness | ||
| Line 47: | Line 47: | ||
Slide the slider, click the spinner arrows or enter a new brightness value (in range [0,255]) to change the LCD backlight value. | Slide the slider, click the spinner arrows or enter a new brightness value (in range [0,255]) to change the LCD backlight value. | ||
| + | |||
| + | ===Behind the Scenes=== | ||
| + | |||
| + | The <code>sysclass_get_level()</code> and <code>sysclass_set_level()</code> functions are responsible for retrieving and setting the backlight's brightness value, respectively. These functions demonstrate a method of interfacing with the <code>/sys</code> virtual filesystem to set and retrieve values to and from the backlight driver in the kernel. | ||
==Summary== | ==Summary== | ||
The <code>brightness</code> C example project creates a GTK+ UI for controlling the backlight-brightness on a EMAC PPC-E7, SoM-9307 or just about any other board with an LCD. | The <code>brightness</code> C example project creates a GTK+ UI for controlling the backlight-brightness on a EMAC PPC-E7, SoM-9307 or just about any other board with an LCD. | ||
Revision as of 16:54, 30 December 2013
This is a guide to the brightness C example project included in the EMAC OE SDK.
This is a simple backlight brightness control. It's written for the EMAC PPC-E7 and SoM-9307 but it will probably run on anything with a backlight. It implements a slider application in GTK+ that directly controls the backlight through its sysfs interface. It has been tested under Xfbdev/Matchbox.
The brightness project builds one executable: brightness.
Contents
Opening, Building and Uploading the Project Files
1. Open the C/C++ editing perspective.
stub
2. Open the project files.
stub
3. Build the project.
stub
4. Upload the executables to the target system.
stub
Usage and Behavior
The brightness C example project creates a GTK+ UI for controlling the backlight brightness. It gives us a slider, a spinner and a textfield.
Hardware Requirements
The brightness C example project is written for the EMAC PPC-E7 and SoM-9307 but it will probably run on anything with a backlight.
Using brightness
From the terminal, first set the DISPLAY variable:
export DISPLAY=:0.0
Then run the brightness C executable:
./brightness
A GTK+ UI appears on the LCD.
Slide the slider, click the spinner arrows or enter a new brightness value (in range [0,255]) to change the LCD backlight value.
Behind the Scenes
The sysclass_get_level() and sysclass_set_level() functions are responsible for retrieving and setting the backlight's brightness value, respectively. These functions demonstrate a method of interfacing with the /sys virtual filesystem to set and retrieve values to and from the backlight driver in the kernel.
Summary
The brightness C example project creates a GTK+ UI for controlling the backlight-brightness on a EMAC PPC-E7, SoM-9307 or just about any other board with an LCD.
