comfilepi:controlling_the_lcd_backlight:index
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comfilepi:controlling_the_lcd_backlight:index [2023/09/14 12:57] COMFILE Technology [Compile] |
comfilepi:controlling_the_lcd_backlight:index [2023/12/06 10:00] (current) COMFILE Technology [Controlling the LCD Backlight] |
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| ====== Controlling the LCD Backlight ====== | ====== Controlling the LCD Backlight ====== | ||
| - | The ComfilePi's LCD backlight is connected to GPIO 34. The backlight can be turned on or off via the command line or via a programming language. | + | The ComfilePi's LCD backlight is connected to one of the panel PC's internal GPIO pins. The backlight can be turned on or off via the command line or via a programming language. |
| Line 257: | Line 257: | ||
| g++ backlight_service.cpp -lX11 -lXext -lpigpiod_if2 -o backlight_service | g++ backlight_service.cpp -lX11 -lXext -lpigpiod_if2 -o backlight_service | ||
| </code> | </code> | ||
| - | |||
| - | Run ''journalctl -t backlight_service -r'' to view the log entries. | ||
| ==== Bash Script Implementation ==== | ==== Bash Script Implementation ==== | ||
| Line 266: | Line 264: | ||
| #!/bin/bash | #!/bin/bash | ||
| - | export DISPLAY=":0.0" | + | PWM_PIN=31 |
| - | + | PIN=34 | |
| - | PIN=34 # CPi-A/B/F/S | + | |
| - | #PIN=44 # CPi-C | + | |
| + | # Set pins as output | ||
| + | raspi-gpio set $PWM_PIN op | ||
| raspi-gpio set $PIN op | raspi-gpio set $PIN op | ||
| + | |||
| + | # Start with both pins HIGH. If either of the | ||
| + | # pins go LOW, the backlight will turn off. | ||
| + | raspi-gpio set $PWM_PIN dh | ||
| + | raspi-gpio set $PIN dh | ||
| + | |||
| + | # Get the current state | ||
| + | CURRENT_STATUS=$(xset q | grep "Monitor is" | awk '{print $3}') | ||
| + | LAST_STATUS=$CURRENT_STATUS | ||
| + | |||
| + | logger -p info -t "backlight_service" -s "Monitor is $CURRENT_STATUS" | ||
| # Loop indefinitely updating backlight in sync with monitor status | # Loop indefinitely updating backlight in sync with monitor status | ||
| Line 277: | Line 286: | ||
| # Check the current monitor status | # Check the current monitor status | ||
| - | current_status=$(xset q | grep "Monitor is" | awk '{print $3}') | + | CURRENT_STATUS=$(xset q | grep "Monitor is" | awk '{print $3}') |
| - | # Control backlight pin according to the monitor status | + | # Only turn the backlight on/off if the Monitor state has changed |
| - | if [ "$current_status" = "On" ]; then | + | if [ "$CURRENT_STATUS" != "$LAST_STATUS" ]; then |
| - | raspi-gpio set $PIN dh | + | logger -p info -t "backlight_service" -s "Monitor is $CURRENT_STATUS" |
| - | else | + | |
| - | raspi-gpio set $PIN dl | + | # Control backlight pin according to the monitor status |
| + | if [ "$CURRENT_STATUS" = "On" ]; then | ||
| + | logger -p info -t "backlight_service" -s "Turning Backlight On" | ||
| + | raspi-gpio set $PIN dh | ||
| + | else | ||
| + | logger -p info -t "backlight_service" -s "Turning Backlight Off" | ||
| + | raspi-gpio set $PIN dl | ||
| + | fi | ||
| + | LAST_STATUS=$CURRENT_STATUS | ||
| fi | fi | ||
| Line 297: | Line 314: | ||
| Add the line ''@xset dpms 0 0 {timeout_in_seconds}'' to the //autostart// file to set the timeout each time the desktop loads. | Add the line ''@xset dpms 0 0 {timeout_in_seconds}'' to the //autostart// file to set the timeout each time the desktop loads. | ||
| + | |||
| + | Run ''journalctl -t backlight_service -r'' to view the log entries. | ||
comfilepi/controlling_the_lcd_backlight/index.1694663820.txt.gz · Last modified: 2023/09/14 12:57 by COMFILE Technology