Diff: CD40147.h

Revision:

0:41932be18e2f

Child:

1:84213005a5d8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CD40147.h	Tue Mar 21 22:04:08 2017 +0000
@@ -0,0 +1,35 @@
+#ifndef CD40147_H
+#define CD40147_H
+
+/**
+ * Handles the CD40147 chip and clones.  These are 10-4 line BCD Priority Encoders.
+ * This simple interface lets you know which of the 10 pins, if any, is
+ * connected to ground.  As per spec, the result can only tell you about the
+ * highest valued pin which is grounded.  Note that pull-up resistors should
+ * be connected to each pin so they are not left floating, which will lead to
+ * unpredictable results.
+ */
+class CD40147 {
+public:
+    /**
+     * Create an instance
+     *
+     * @param a   Data input line for least significat bit (bit 0)
+     * @param b   Data input line for bit 1
+     * @param c   Data input line for bit 2
+     * @param d   Data input line for most significat bit (bit 3)
+     */
+    inline CD40147(PinName a, PinName b, PinName c, PinName d) :  _in(a,b,c,d) {}
+
+    /**
+     * Provides the highest valued input that was set, as this is a priority
+     * encoder chip.  The value 0x0f means no pin is connected to ground.
+     * Otherwise a value of 0-9 refers to pins 0-9 being grounded.
+     */
+    inline uint8_t read() {return (~_in.read()) & 0x0f;}
+
+protected:
+    BusIn _in;
+};
+
+#endif