make the brightness setting logarithmic, which looks linear to the eye

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16161 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 7 insertions, 4 deletions

diff --git a/firmware/export/config-gigabeat.h b/firmware/export/config-gigabeat.h
index 62e7e26713..70664262d8 100644
--- a/firmware/export/config-gigabeat.h
+++ b/firmware/export/config-gigabeat.h
@@ -56,9 +56,9 @@
 #define HAVE_BUTTONLIGHT_BRIGHTNESS
 
 /* Main LCD backlight brightness range and defaults */
-#define MIN_BRIGHTNESS_SETTING          0   /* 0.5 mA */
-#define MAX_BRIGHTNESS_SETTING          63  /* 32 mA */
-#define DEFAULT_BRIGHTNESS_SETTING      39  /* 20 mA */
+#define MIN_BRIGHTNESS_SETTING          1   /* 0.5 mA */
+#define MAX_BRIGHTNESS_SETTING          12  /* 32 mA */
+#define DEFAULT_BRIGHTNESS_SETTING      10  /* 16 mA */
 
 /* Define this if you have a software controlled poweroff */
 #define HAVE_SW_POWEROFF
diff --git a/firmware/target/arm/s3c2440/gigabeat-fx/backlight-meg-fx.c b/firmware/target/arm/s3c2440/gigabeat-fx/backlight-meg-fx.c
index 645f3c1e09..913deab371 100644
--- a/firmware/target/arm/s3c2440/gigabeat-fx/backlight-meg-fx.c
+++ b/firmware/target/arm/s3c2440/gigabeat-fx/backlight-meg-fx.c
@@ -30,6 +30,7 @@
 
 #ifndef BOOTLOADER
 static void led_control_service(void);
+const int log_brightness[12] = {0,1,2,3,5,7,10,15,22,31,44,63};
 
 static enum sc606_states
 {
@@ -70,9 +71,11 @@ static unsigned short buttonlight_trigger_now;
 /* Assumes that the backlight has been initialized */
 void _backlight_set_brightness(int brightness)
 {
+    /* clamp the brightness value */
+    brightness = MAX(1, MIN(12, brightness));
     /* stop the interrupt from messing us up */
     backlight_control = BACKLIGHT_CONTROL_IDLE;
-    backlight_brightness = brightness;
+    backlight_brightness = log_brightness[brightness - 1];
     backlight_control = BACKLIGHT_CONTROL_SET;
 }