1 files changed, 119 insertions, 0 deletions
diff --git a/source/arduino/map.rst b/source/arduino/map.rst
new file mode 100644
index 0000000..65647fa
--- /dev/null
+++ b/source/arduino/map.rst
@@ -0,0 +1,119 @@
+.. _arduino-map:
+
+map(value, fromLow, fromHigh, toLow, toHigh)
+============================================
+
+Description
+-----------
+
+Re-maps a number from one range to another. That is, a **value** of
+**fromLow** would get mapped to **toLow**, a value of **fromHigh**
+to **toHigh**, values in-between to values in-between, etc.
+
+
+
+Does not constrain values to within the range, because out-of-range
+values are sometimes intended and useful. The constrain() function
+may be used either before or after this function, if limits to the
+ranges are desired.
+
+
+
+Note that the "lower bounds" of either range may be larger or
+smaller than the "upper bounds" so the map() function may be used
+to reverse a range of numbers, for example
+
+
+
+``y = map(x, 1, 50, 50, 1);``
+
+
+
+The function also handles negative numbers well, so that this
+example
+
+
+
+``y = map(x, 1, 50, 50, -100);``
+
+
+
+is also valid and works well.
+
+
+
+The map() function uses integer math so will not generate
+fractions, when the math might indicate that it should do so.
+Fractional remainders are truncated, and are not rounded or
+averaged.
+
+
+
+Parameters
+----------
+
+value: the number to map
+
+
+
+fromLow: the lower bound of the value's current range
+
+
+
+fromHigh: the upper bound of the value's current range
+
+
+
+toLow: the lower bound of the value's target range
+
+
+
+toHigh: the upper bound of the value's target range
+
+
+
+Returns
+-------
+
+The mapped value.
+
+
+
+Example
+-------
+
+::
+
+    /* Map an analog value to 8 bits (0 to 255) */
+    void setup() {}
+    
+    void loop()
+    {
+      int val = analogRead(0);
+      val = map(val, 0, 1023, 0, 255);
+      analogWrite(9, val);
+    }
+
+
+
+Appendix
+~~~~~~~~
+
+For the mathematically inclined, here's the whole function
+
+
+
+::
+
+    long map(long x, long in_min, long in_max, long out_min, long out_max)
+    {
+      return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+    }
+
+
+
+See Also
+--------
+
+
+-  `constrain <http://arduino.cc/en/Reference/Constrain>`_\ ()