Diff: SerialDigitalInput.h

Revision:

0:6cb2eaf8b133

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SerialDigitalInput.h	Sun Aug 19 05:21:20 2018 +0000
@@ -0,0 +1,84 @@
+/*
+ * SerialDigitalInput.h
+ *
+ *  Created on: 2018Äê2ÔÂ10ÈÕ
+ *      Author: caoyuan9642
+ */
+
+#ifndef TELESCOPE_SERIALDIGITALINPUT_H_
+#define TELESCOPE_SERIALDIGITALINPUT_H_
+
+#include "mbed.h"
+
+/**
+ * A serial interfaced digital input
+ * Example application is to read a parallel input (8~32 bits) using cascaded 74xx165.
+ */
+template<uint8_t N>
+class SerialDigitalInput
+{
+public:
+	SerialDigitalInput(PinName c, PinName l, PinName d) :
+			clk(DigitalOut(c)), load(DigitalOut(l)), data(DigitalIn(d))
+	{
+		if (clk == NC || load == NC || data == NC)
+		{
+			fprintf(stderr, "ERROR in SerialDigitalInput: PIN(s) undefined");
+			return;
+		}
+
+		/*Prepare for next reading*/
+		clk = 0;
+		load = 1;
+	}
+	virtual ~SerialDigitalInput()
+	{
+	}
+
+	uint8_t getBits() const
+	{
+		return N;
+	}
+
+	uint32_t read()
+	{
+		uint32_t value = 0;
+		/*Load the shift register*/
+		clk = 0;
+		load = 0;
+
+		delay();
+
+		/*Lock the shift register*/
+		load = 1;
+		for (int i = 0; i < N; i++)
+		{
+			/*Read value*/
+			value = (value << 1) + (data != 0);
+			/*Clock. Now the next bit will be loaded*/
+			clk = 1;
+			/*Delay*/
+			delay();
+			/*Reset clock*/
+			clk = 0;
+			/*Delay*/
+			delay();
+		}
+		return value;
+	}
+
+
+private:
+	DigitalOut clk;
+	DigitalOut load;
+	DigitalIn data;
+
+	void delay(){
+		uint16_t i=100;
+		while(i--);
+	}
+};
+
+#endif /* TELESCOPE_SERIALDIGITALINPUT_H_ */
+
+