1 files changed, 61 insertions, 0 deletions
diff --git a/bin/level_calc.py b/bin/level_calc.py
new file mode 100755
index 0000000..c792bba
--- /dev/null
+++ b/bin/level_calc.py
@@ -0,0 +1,61 @@
+#!/usr/bin/env python
+
+import math
+
+def main(args):
+    """Calculates PWM levels for visually-linear steps.
+    """
+    # Get parameters from the user
+    v = dict()
+    questions = [
+            (int, 'pwm_min', 6, 'Lowest visible PWM level, for moon mode:'),
+            (float, 'lm_min', 0.25, 'How bright is moon mode, in lumens?'),
+            (int, 'pwm_max', 255, 'Highest PWM level:'),
+            (float, 'lm_max', 1000, 'How bright is the highest level, in lumens?'),
+            (int, 'num_levels', 4, 'How many total levels do you want?'),
+            ]
+    for typ, name, default, text in questions:
+        value = get_value(text, default, args)
+        if not value:
+            value = default
+        else:
+            value = typ(value)
+        v[name] = value
+
+    # change these values for each device:
+    #pwm_min = 0     # lowest visible PWM level, for moon mode
+    #lm_min = 10.0   # how bright is moon mode, in lumens?
+    #pwm_max = 255   # highest PWM level
+    #lm_max = 1300   # how bright is the highest level, in lumens?
+    #num_levels = 4  # how many total levels do you want?
+
+    # The rest should work fine without changes
+    visual_min = math.pow(v['lm_min'], 1.0/3)
+    visual_max = math.pow(v['lm_max'], 1.0/3)
+    step_size = (visual_max - visual_min) / (v['num_levels']-1)
+    modes = []
+    goal = visual_min
+    for i in range(v['num_levels']):
+        pwm_float = (((goal**3) / v['lm_max']) * (256-v['pwm_min'])) + v['pwm_min'] - 1
+        pwm = int(round(pwm_float))
+        pwm = max(min(pwm,v['pwm_max']),v['pwm_min'])
+        modes.append(pwm)
+        print '%i: visually %.2f (%.2f lm): %.2f/255' % (i+1, goal, goal ** 3, pwm_float)
+        goal += step_size
+
+    print 'PWM values:', ','.join([str(i) for i in modes])
+
+def get_value(text, default, args):
+    if args:
+        result = args[0]
+        del args[0]
+    else:
+        print text, '(%s)' % (default),
+        result = raw_input()
+    result = result.strip()
+    return result
+
+if __name__ == "__main__":
+    import sys
+    main(sys.argv[1:])
+