Diff: main.cpp

Revision:

0:0db8165396ae

Child:

1:0e3453d2d0cc

diff -r 000000000000 -r 0db8165396ae main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Nov 05 12:27:11 2012 +0000
@@ -0,0 +1,50 @@
+/*
+ * SOURCE FILE : main.cpp
+ *
+ * Test program to see if a 485 communications link is working.
+ * This is designed to run on the LPC11U24 which only has a single
+ * serial port which uses pin 9 for TX and pin 10 for RX. Note that
+ * this is the same serial port that transmits over the USB cable to the PC.
+ *
+ */
+ 
+#include "mbed.h"
+
+/****************/
+/* MAIN PROGRAM */
+/****************/
+int main() {
+    // Digital output connected to on-board LED1.
+    DigitalOut myled(LED1);
+    // Digital output used to enable the 485 transmitter
+    // and simultaneously disable the received.
+    DigitalOut txEnable( p11 );
+    txEnable = 0;
+    // Serial port to PC and also to pins 9 and 10.
+    Serial pc( USBTX, USBRX );
+    // Set baud rate and protocol.
+    pc.baud( 38400 );
+    pc.format( 8, Serial::None, 1 );
+    // Message to send.
+    char message[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ\r\n";
+    // Do following until power goes off.
+    while( true ) {
+        // Toggle state of LED.
+        myled = ( myled ? 0 : 1 );
+        // Turn on the transmitter and disable receiver.
+        txEnable = 1;
+        // Transmit a message.
+        char *ptr = message;
+        while( *ptr != 0 ) {
+            if( pc.writeable() ) {
+                pc.putc( *ptr++ );
+            }
+        }
+        // Wait 300 micro seconds to let last byte transmit.
+        wait_us( 300 );
+        // Turn off the transmitter and enable the receiver.
+        txEnable = 0;
+        // Wait 1 second.
+        wait_us( 1000000 );
+    }
+}