Diff: usb-serial.cpp

Revision:

0:c6ee363ac724

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/usb-serial.cpp	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,65 @@
+#include "mbed.h"
+#include "usb-serial.h"
+
+volatile unsigned wp, rp;
+static const int outbuf_size = 128;
+static const unsigned pointer_mask = 0x007fU;
+char usb_outbuf[outbuf_size];
+static bool overflow;
+DigitalOut mydiag(p22);;
+
+extern "C" static void txReadyISR() __irq {
+
+    mydiag = 1;
+    // If the output buffer has data, copy the head to the UART
+    if (rp != wp) {
+        LPC_UART0->THR = usb_outbuf[rp];
+        rp = (rp+1) & pointer_mask;
+    }
+    
+    // If the output buffer is empty, disable the transmit buffer empty 
+    // interrupt
+    if (rp == wp)
+       LPC_UART0->IER = 0;
+
+
+    mydiag = 0;
+}
+
+void usb_serial_init(void) {
+    
+    // init the output FIFO
+    wp = 0; rp = 0;
+    overflow = false;
+
+    // init the serial port
+    Serial usb_serial(USBTX, USBRX);    
+    usb_serial.baud(/*115200*/230400);
+    usb_serial.format(8, Serial::None, 1);
+    LPC_UART0->FCR = 7UL;
+    NVIC_SetVector(UART0_IRQn, (uint32_t)txReadyISR);
+    NVIC_EnableIRQ(UART0_IRQn);
+    LPC_UART0->THR = 0; // this is required to start the interrupts, don't understand why
+}
+
+bool usb_serial_putc(char c) {
+
+    if (overflow == false) {
+        usb_outbuf[wp] = c;      
+        LPC_UART0->IER = 0; // ---- critical
+        wp = (wp+1) & pointer_mask;
+
+        if (wp == rp)
+            overflow = true;
+        else
+            overflow = false;
+
+        LPC_UART0->IER = 2UL;  // ---- \critical
+    } else {
+        // reinit the output FIFO
+        wp = 0; rp = 0;
+        overflow = false;
+    }
+    
+    return overflow;
+}
\ No newline at end of file