Diff: gsmqueue.cpp

Revision:

29:bc5f53f2922a

Parent:

27:fe1c7eaf5b88

Child:

32:424896b5adbe

--- a/gsmqueue.cpp	Thu Apr 23 02:06:55 2015 +0000
+++ b/gsmqueue.cpp	Sat Apr 25 15:39:00 2015 +0000
@@ -8,11 +8,18 @@
  
 #define LAST_UNPRINTABLE_CHAR 31
 
-extern Serial pc;
-extern Serial gsm;
+//External variables
+extern Serial pc;   //Print data to serial connection with computer
+extern Serial gsm;  //UART connection with GSM
 
-char buffer[BUFFER_LENGTH];
-char* queueHead;
+//Internal variables for a queue (wrap-around implementation)
+//Note that the DMA (direct memory access) stores data in this queue. Therefore, QUEUETAIL is incremented
+//by the DMA and we only read its value. Our queue's purpose is to read data communicated to us 
+//by the GSM without having to consume processor cycles. Unfortunately when we write data to the Serial
+//port, the DMA will still write it to the buffer. For this reason, the sendCommand() function counts
+//the number of characters we send over UART so we can ignore those characters in the queue.
+char buffer[BUFFER_LENGTH];  //Stores the characters in the queue
+char* queueHead;    //Queue head - marks where to read from next
 char* queueHeadExp; //Expected location of queueHead after gsm.puts() finishes executing
 
 
@@ -220,10 +227,4 @@
 {
     queueHead = QUEUETAIL;   
 }
-    
-//Reset the GSM DMA idle bit to 0
-void resetGSMIdleBit()
-{
-    UART_S1_REG(UART3) &= ~UART_S1_IDLE_MASK;
-}