Diff: USB_receive_6.cpp

Revision:

14:5767d651d624

diff -r d60c746c097c -r 5767d651d624 USB_receive_6.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/USB_receive_6.cpp	Thu Aug 14 20:18:15 2014 +0000
@@ -0,0 +1,198 @@
+// L. van der Kolk, ELVEDEKA, Holland //
+// File:  USB_receive_6.cpp     
+
+#include "mbed.h"
+#include "MODSERIAL.h" 
+
+extern MODSERIAL USB;
+extern int FSdata_received_flag;
+
+//------- debug only ---------------------
+//extern MODSERIAL SERIAL_DEBUG;
+//----------------------------------------
+   
+void decode_string(int nummer_of_chars);
+void read_datafields(int command_number);
+
+#define max_string_length 100 // : max length of received string starting with $ and ending with CR/LF
+#define min_string_length 10 // : min length of received string starting with $ and ending with CR/LF
+char string_received[max_string_length + 3]; // : holds received string starting with $ and ending with CR/LF
+
+#define message_header "$PCDU"  // : common message header in all messages
+#define max_commas 10  // : max. nr of possible field separating commas in a valid message string to CDU
+int comma[max_commas];      // : array with positions of all found commas in string_receved[]
+
+#define max_nr_of_commands 13   // : max nr of possible FS-to-CDU commands
+// Define array of pointers to possible FS-to-CDU commands with 3 characters:
+const char *command[max_nr_of_commands] = {
+   "123",    // : no valid CDU command nr. 0 , used for debugging only
+   "MSG",    // : command nr. 1
+   "EXC",    // : command nr. 2
+   "BLT",    // : command nr. 3
+   "SBY",    // : command nr. 4
+   "CLS",    // : command nr. 5
+   "SBC",    // : command nr. 6
+   "WTX",    // : command nr. 7
+   "ETX",    // : command nr. 8
+   "KTX",    // : command nr. 9
+   "FAI",    // : command nr.10
+   "DPY",    // : command nr.11
+   "OFS",    // : command nr.12
+};
+
+void collect_FSdata()  {
+     // Function reads characters from FS written in receive buffer.
+     // Wiil be called after each RX receive interrupt, so characters will allways be stored.
+     // When analyze_busy is false, function will start reading characters from defined buffer and 
+     // collects strings starting with $ and ending with CR/LF. 
+     // Strings shorter than min_string_length or longer than max_string_length will be ignored,
+     // others will be analyzed further.
+     // After analyzing, flag analyze_busy will be set to false again.
+    static int $_detected = false;      // : no valid begin of string detected (init only on first call)
+    static int string_pntr = 0;         // : pointer at begin of string (init only on first call)
+    static int nr_of_received_char = 0; // : counter of received characters (init only on first call)
+           char rx_char;                // : character which is analyzed 
+             
+ if ( FSdata_received_flag == false ) {  // : process received chars only if no decoding busy now
+   while ( !USB.rxBufferEmpty() )  // : do as long as USB receive buffer is not empty
+   {    rx_char = USB.getc(); // : get a char from Rx buffer
+       
+        // ----------- Debug only ! ---------------------------------------------
+        //SERIAL_DEBUG.putc(rx_char);    // : unprotected immediate echo of char 
+        // ----------------------------------------------------------------------
+     
+        // Check for string starting with $ char:
+        if ( rx_char == '$' && $_detected == false ){
+            $_detected = true;  // : begin of string is detected 
+            string_pntr = 0;    // : set pointer to begin of string_received[] buffer
+        }    
+        string_received[string_pntr] = rx_char;
+        string_pntr++;     
+        if (string_pntr >= max_string_length) {
+            // command string looks too long, so start all over again:
+            string_pntr = 0;  // : set pointer back to begin of string_received[] again
+            nr_of_received_char = 0;   // : reset number of received chars
+            $_detected = false;
+            FSdata_received_flag = false;
+        }    
+        if ( rx_char == '\r' && $_detected == true ) {             
+            if ( string_pntr > min_string_length ) { // : check minimum string length 
+                // Received string can be interesting now because
+                // it starts with '$' AND it ends on New-Line  AND
+                // it has a minimum length AND it is not too long:
+                string_received[string_pntr] = '\0'; // : mark end of string
+                
+                FSdata_received_flag = true;
+                 
+                // ----------- Debug only ! -------------------------------------------
+                // SERIAL_DEBUG.printf("string_received from USB: %s",string_received );  
+                // --------------------------------------------------------------------
+               
+                nr_of_received_char = string_pntr;
+                //Call decoder to analyse this string:
+                 decode_string(nr_of_received_char);
+                // Get ready for receiving new commands:
+                $_detected = false;
+                string_pntr = 0;  // : set pointer back to begin of string_received[] again
+                nr_of_received_char = 0;   // : reset number of received chars
+            }
+            else {
+                $_detected = false;  
+                string_pntr = 0; // : set pointer back to begin of string_received[] again
+                nr_of_received_char = 0;   // : reset number of received chars
+                FSdata_received_flag = false;
+            }
+        }    
+   } 
+    
+ } 
+}
+    
+void decode_string(int nummer_of_chars)
+{   // -- This function decodes a received $.....CR/LF string written in string_received[] --
+    // First it checks for a valid checksum and reads the positions of commas in the string.
+    // If checksum is OK, it will continue to look for valid 3 char FS-to-CDU commands.
+    // When a valid command is found, data fields will be analyzed further using the found positions
+    // of commas in the string.
+    int  i,c, equal;
+    char byte_read, exor_byte;
+    char command_string[6], received_checksum[4], calc_checksum[4];
+   // Get checksum and position of commas in string_received[] :
+    exor_byte = 0;
+    i = 1;  // : i points to first char after $
+    c = 1;  // : position of first comma
+      do {
+          byte_read = string_received[i];
+          if (byte_read == ',' && c < max_commas) {
+              comma[c] = i;
+              c++;
+          }
+          if (byte_read == '*') break;
+          exor_byte = exor_byte ^ byte_read;
+          i++;
+      } while ( i < nummer_of_chars );
+      
+
+    // ----------- Debug only ------------------------------------------- 
+    //SERIAL_DEBUG.printf("commas found : %d\n",c-1 );  // : show commas 
+    // ------------------------------------------------------------------
+
+    i++;   // : i points to first checksum char after char *
+    strncpy(received_checksum,&string_received[i],2);   // : copy 2 char checksum after * 
+    // Get calculated checksum by transforming exor_byte in 2 hex chars (with upper case A-F) :
+    sprintf(calc_checksum,"%02X",exor_byte); // : + extra NULL char added by sprintf 
+    equal = strncmp(received_checksum,calc_checksum,2);
+    
+    // ******************************************************************************************
+    // -- Force checksum to allways OK : < -- debug only !!
+    equal = 0;
+    // ******************************************************************************************
+    
+    if (equal != 0) {
+       // ----------- Debug only ------------------------------------------------------- 
+       //SERIAL_DEBUG.printf("checksum is NOT OK ! \n" );  // : show message for debugging
+       // ------------------------------------------------------------------------------
+       FSdata_received_flag = false;
+    }
+    else { // checksum is OK, go on:
+        // Check for 5 char "$PCDU" header:
+        equal = strncmp(string_received,message_header,strlen(message_header));
+          if (equal != 0) {
+
+            // ----------- Debug only ---------------------------------------------------
+            //SERIAL_DEBUG.printf("no $PCDU header in message !\n" );  // : show message 
+            // --------------------------------------------------------------------------
+
+            FSdata_received_flag = false;
+          }
+          else {
+               // Read 3 char command after message_header:
+               strncpy(command_string,&string_received[strlen(message_header)],3);
+
+               // ----------- Debug only ---------------------------------------------------------------------
+               //SERIAL_DEBUG.printf("\ncommand found : %3s\n",command_string ); // : show command for debugging 
+               //SERIAL_DEBUG.printf("commas found : %d\n",c-1 );               // : show commas for debugging
+               // --------------------------------------------------------------------------------------------
+ 
+               // Compare found string with known 3 char command list:
+               i = 0; 
+               do {
+                  equal = strncmp(&command_string[0],command[i],3);
+                  if( equal == 0) break;
+                  i++;
+               } while ( i < max_nr_of_commands);
+              
+                // ----------- Debug only ---------------------------------------------------------------
+                //SERIAL_DEBUG.printf("command number is : %d\n",i );  // : show command nr for debugging 
+                // --------------------------------------------------------------------------------------
+                
+               if (equal == 0) {
+                 // Command is known now, so now read all data fields:
+                 read_datafields(i);
+               }
+               else FSdata_received_flag = false;
+         } 
+    } 
+    
+ }
+