Sam Grove / BufferedSerial

Inherit from Serial and use software buffers for TX and RX. This allows the UART peripherals to operate in a IRQ driven mode. Overrides most (but not all) stdio functions as Serial did

Dependencies:   Buffer

Dependents:   buffered_serial_test BLE_Police_HRM evena_BLE_Police_HRM df-2014-workshop-rfid-case-generator-k64f ... more

Example

 #include "mbed.h"
 #include "BufferedSerial.h"

 BufferedSerial pc(USBTX, USBRX);

 int main()
 {
     pc.baud(115200);
   
     while(1)
     {
         Timer s;
       
         s.start();
         pc.printf("Hello World - buff\n");
         int buffered_time = s.read_us();
         wait(0.1f); // give time for the buffer to empty
       
         s.reset();
         printf("Hello World - poll\n");
         int polled_time = s.read_us();
         s.stop();
         wait(0.1f); // give time for the buffer to empty
       
         pc.printf("printf buffered took %d us\n", buffered_time);
         pc.printf("printf polled took %d us\n", polled_time);
         wait(0.5f);
     }
 }

Diff: BufferedSerial.cpp

Revision:
0:a977d0a3d81e
Child:
1:57a11fb5d529
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BufferedSerial.cpp	Thu May 23 19:31:30 2013 +0000
@@ -0,0 +1,122 @@
+/**
+ * @file    BufferedSerial.cpp
+ * @brief   Software Buffer - Extends mbed Serial functionallity adding irq driven TX and RX
+ * @author  sam grove
+ * @version 1.0
+ * @see     
+ *
+ * Copyright (c) 2013
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BufferedSerial.h"
+#include "LogUtil.h"
+#include <stdarg.h>
+
+BufferedSerial::BufferedSerial(PinName tx, PinName rx, const char* name)
+    : Serial(tx, rx, name)
+{
+    Serial::attach(this, &BufferedSerial::rxIrq, Serial::RxIrq);
+    Serial::attach(this, &BufferedSerial::txIrq, Serial::TxIrq);
+    
+    return;
+}
+
+BufferedSerial::~BufferedSerial(void)
+{
+    Serial::attach(NULL, Serial::RxIrq);
+    Serial::attach(NULL, Serial::TxIrq);
+    
+    return;
+}
+
+int BufferedSerial::readable(void)
+{
+    return _rxbuf.available();  // note: look if things are in the buffer
+}
+
+int BufferedSerial::writeable(void)
+{
+    return 1;   // buffer allows overwriting by design, always true
+}
+
+int BufferedSerial::getc(void)
+{
+    return _rxbuf;   // note: pulling from the buffer
+}
+
+int BufferedSerial::putc(int c)
+{
+    _txbuf = (char)c;
+    BufferedSerial::txIrq();    // prime the txirq to stoke transmit
+    
+    return c;
+}
+
+int BufferedSerial::puts(const char *s)
+{
+    const char *size = s;
+    
+    while(*(s) != 0)
+    {
+        _txbuf = *(s++);
+    }
+    BufferedSerial::txIrq();    // prime the txirq to stoke transmit
+    
+    return s - size;
+}
+
+int BufferedSerial::printf(const char* format, ...)
+{
+    char buf[256] = {0};
+    int r = 0;
+    
+    va_list arg;
+    va_start(arg, format);
+    r = vsprintf(buf, format, arg);
+    // this may not hit the heap but should alert the user anyways
+    if(r > sizeof(buf))
+    {
+        ERROR("Buffer Overwrite Occured!\n");
+    }
+    r = BufferedSerial::puts(buf);
+    va_end(arg);
+    
+    return r;
+}
+
+void BufferedSerial::rxIrq(void)
+{
+    // read from the peripheral and see if things are available
+    while(serial_readable(&_serial))
+    {
+        _rxbuf = serial_getc(&_serial); // if so load them into a buffer
+    }
+    
+    return;
+}
+
+void BufferedSerial::txIrq(void)
+{
+    // see if there is room in the hardware buffer and something is in the software buffer
+    while(serial_writable(&_serial) && _txbuf.available())
+    {
+        serial_putc(&_serial, (int)_txbuf.get());
+    }
+    
+    return;
+}
+
+
+