Diff: serialIO.cpp

Revision:

6:d772ad205bc7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/serialIO.cpp	Tue Feb 11 05:24:56 2014 +0000
@@ -0,0 +1,101 @@
+#include "mbed.h"
+#include "pinout.h"
+#include "serialIO.h"
+
+// buffer for TX and RX
+char tx_buffer[buffer_size];
+char rx_buffer[buffer_size];
+// buffer for sscanf and sprintf
+char tx_line[80];
+char rx_line[80];
+
+// index marking the begin/end of rx_buffer and tx_buffer
+volatile int tx_out = 0;
+volatile int tx_in = 0;
+volatile int rx_out = 0;
+volatile int rx_in = 0;
+
+// Copy tx line buffer to large tx buffer for tx interrupt routine
+void send_line() {
+    int i;
+    char temp_char;
+    bool empty;
+    i = 0;
+// Start Critical Section - don't interrupt while changing global buffer variables
+    NVIC_DisableIRQ(USB_IRQn);
+    empty = (tx_in == tx_out);
+    while ((i==0) || (tx_line[i-1] != '\n')) {
+// Wait if buffer full
+        if (((tx_in + 1) % buffer_size) == tx_out) {
+// End Critical Section - need to let interrupt routine empty buffer by sending
+            NVIC_EnableIRQ(USB_IRQn);
+            while (((tx_in + 1) % buffer_size) == tx_out) {
+            }
+// Start Critical Section - don't interrupt while changing global buffer variables
+            NVIC_DisableIRQ(USB_IRQn);
+        }
+        tx_buffer[tx_in] = tx_line[i];
+        i++;
+        tx_in = (tx_in + 1) % buffer_size;
+    }
+    if (pc.writeable() && (empty)) {
+        temp_char = tx_buffer[tx_out];
+        tx_out = (tx_out + 1) % buffer_size;
+// Send first character to start tx interrupts, if stopped
+        pc.putc(temp_char);
+    }
+// End Critical Section
+    NVIC_EnableIRQ(USB_IRQn);
+    return;
+}
+
+// Interupt Routine to write out data to serial port
+void Tx_interrupt() {
+// Loop to fill more than one character in UART's transmit FIFO buffer
+// Stop if buffer empty
+    while ((pc.writeable()) && (tx_in != tx_out)) {
+        pc.putc(tx_buffer[tx_out]);
+        tx_out = (tx_out + 1) % buffer_size;
+    }
+    return;
+}
+
+// Read a line from the large rx buffer from rx interrupt routine
+void read_line() {
+    int i;
+    i = 0;
+// Start Critical Section - don't interrupt while changing global buffer variables
+    NVIC_DisableIRQ(USB_IRQn);
+// Loop reading rx buffer characters until end of line character
+    while ((i==0) || (rx_line[i-1] != '\r')) {
+// Wait if buffer empty
+        if (rx_in == rx_out) {
+// End Critical Section - need to allow rx interrupt to get new characters for buffer
+            NVIC_EnableIRQ(USB_IRQn);
+            while (rx_in == rx_out) {
+            }
+// Start Critical Section - don't interrupt while changing global buffer variables
+            NVIC_DisableIRQ(USB_IRQn);
+        }
+        rx_line[i] = rx_buffer[rx_out];
+        i++;
+        rx_out = (rx_out + 1) % buffer_size;
+    }
+// End Critical Section
+    NVIC_EnableIRQ(USB_IRQn);
+    rx_line[i-1] = 0;
+    return;
+}
+
+// Interupt Routine to read in data from serial port
+void Rx_interrupt() {
+// Loop just in case more than one character is in UART's receive FIFO buffer
+// Stop if buffer full
+    while ((pc.readable()) && (((rx_in + 1) % buffer_size) != rx_out)) {
+        rx_buffer[rx_in] = pc.getc();
+// Uncomment to Echo to USB serial to watch data flow
+//        monitor_device.putc(rx_buffer[rx_in]);
+        rx_in = (rx_in + 1) % buffer_size;
+    }
+    return;
+}