Diff: RS485.h

Revision:

0:dccd2df6a07c

Child:

1:f7cead04d73e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RS485.h	Mon Feb 27 21:53:25 2017 +0000
@@ -0,0 +1,125 @@
+
+/**
+ * @file    RS485.h
+ * @brief   RS485 protocol - using half duplex method
+ * @author  Aaron Allar
+ * @version 1.0
+ * @see
+ *
+ * based on this method https://www.gammon.com.au/forum/?id=11428
+ * 
+ * Can send from 1 to 255 bytes from one node to another with:
+ *
+ * Packet start indicator (STX)
+ * Each data byte is doubled and inverted to check validity
+ * Packet end indicator (ETX)
+ * Packet CRC (checksum)
+ */
+
+
+
+#ifndef RS485_H
+#define RS485_H
+#include <BufferedSerial.h>
+#include "mbed.h"
+
+/** A serial port (UART) is used for RS485
+ *  
+ *
+ * Example:
+ * @code
+ *  #include "mbed.h" 
+ *  #include <RS485.h>
+ *  Serial pc(USBTX, USBRX); 
+ *  RS485 RS485(PC_10,PC_11,PB_3); // Tx, Rx , enable pin(future use)
+ * 
+ *  DigitalOut ho(PB_3);
+ *  typedef uint8_t byte;
+ * 
+ *  byte regvalue[9];
+ *  byte data[9] = {0x01,0x04,0x00,0x48,0x00,0x02,0xf1,0xdd};//your data
+ *  int main()
+ *  {
+ *    pc.printf("main\n");
+ *    while(1) {
+ *       pc.printf("Starting\n");
+ *       ho = 1;                  // 3.3V output from digital out pin
+ *       RS485.sendMsg(data,sizeof(data));
+ *       wait_ms(600);            // Must wait for all the data to be sent   
+ *       ho = 0;                  // 0V output from digital out pin
+ *       pc.printf("Getting data\n");
+ *       if(RS485.readable() >0){
+ *           memset(regvalue,0,sizeof(regvalue));
+ *           wait_ms(200);
+ *           RS485.recvMsg(regvalue,sizeof(data),500);
+ *           wait_ms(200);
+ *           for (int count = 0; count < 9; count++) {
+ *               pc.printf("%X - ", regvalue[count]);
+ *           }
+ *       }else printf("No Data\n");
+ *       printf("Done\n");
+ *       wait_ms(1000);
+ *    }
+ *  } 
+ * @endcode
+ */
+
+
+/**
+ *  @class RS485
+ *  @communicating using MAX485 modules
+ */
+
+class RS485 : public BufferedSerial
+{
+private:
+    typedef unsigned int word;
+    typedef uint8_t byte;
+    typedef uint8_t boolean;
+    typedef void (*voidFuncPtr)(void);
+    
+public:
+    /** Create a BufferedSerial port, connected to the specified transmit and receive pins
+     *  @param tx Transmit pin
+     *  @param rx Receive pin
+     *  @param dere Enable pin (currently not implemented)
+     *  @note uses BufferedSerial
+     */
+    RS485(PinName tx, PinName rx, PinName dere);
+
+    /** calculate 8-bit CRC
+    *  cyclic redundancy check
+    *  @addr byte pointer of information to use (typical an char array)
+    *  @len length of byte of information were converting
+    *  @return the CRC byte
+    */
+    static byte crc8 (const byte *addr, byte len);
+    
+    /** sendComplemented byte
+    *  send a byte complemented, repeated
+    *       only values sent would be (in hex):
+    *       0F, 1E, 2D, 3C, 4B, 5A, 69, 78, 87, 96, A5, B4, C3, D2, E1, F0
+    *  @what the byte to complement
+    */
+    void sendComplemented (const byte what);
+    
+    /** send message
+    *  cyclic redundancy check
+    *  @data the data to be sent through RS485
+    *  @length length of the data 
+    *  @note puts STX at start, ETX at end, and add CRC
+    */   
+    void sendMsg (const byte * data, const byte length);
+    
+    /** receive message
+    *  reads serial port and populates data
+    *  @data buffer to receive into
+    *  @length length of the data 
+    *  @timeout clock_mseconds before timing out
+    *  
+    */
+    byte recvMsg (byte * data, const byte length, unsigned long timeout);
+      
+
+};
+#endif
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