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);
     }
 }

Files at this revision

API Documentation at this revision

Comitter:
sam_grove
Date:
Mon Dec 30 18:16:39 2013 +0000
Parent:
3:6b76fcf27545
Child:
5:4d6a311fc8bf
Commit message:
Disable TX IRQ when nothing is left in the buffer (FRDM support). Tested example program with KL46Z, KL25Z and LPC11U24. LPC1768 doesn't work. Need to investigate.

Changed in this revision

Buffer.lib Show annotated file Show diff for this revision Revisions of this file
BufferedSerial.cpp Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Buffer.lib	Mon Dec 30 18:16:39 2013 +0000
@@ -0,0 +1,1 @@
+https://mbed.org/users/sam_grove/code/Buffer/#cd0a1f4c623f
--- a/BufferedSerial.cpp	Wed Jun 12 20:40:15 2013 +0000
+++ b/BufferedSerial.cpp	Mon Dec 30 18:16:39 2013 +0000
@@ -3,7 +3,7 @@
  * @brief   Software Buffer - Extends mbed Serial functionallity adding irq driven TX and RX
  * @author  sam grove
  * @version 1.0
- * @see     
+ * @see
  *
  * Copyright (c) 2013
  *
@@ -21,15 +21,13 @@
  */
 
 #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;
 }
 
@@ -37,7 +35,7 @@
 {
     Serial::attach(NULL, Serial::RxIrq);
     Serial::attach(NULL, Serial::TxIrq);
-    
+
     return;
 }
 
@@ -60,21 +58,20 @@
 {
     _txbuf = (char)c;
     BufferedSerial::prime();
-    
+
     return c;
 }
 
 int BufferedSerial::puts(const char *s)
 {
     const char* ptr = s;
-    
-    while(*(ptr) != 0)
-    {
+
+    while(*(ptr) != 0) {
         _txbuf = *(ptr++);
     }
     _txbuf = '\n';  // done per puts definition
     BufferedSerial::prime();
-    
+
     return (ptr - s) + 1;
 }
 
@@ -82,18 +79,17 @@
 {
     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 Overflow on the Stack Occured!\n");
+    if(r > sizeof(buf)) {
+        error("%s %d buffer overwrite!\n", __FILE__, __LINE__);
     }
+    va_end(arg);
     r = BufferedSerial::write(buf, r);
-    va_end(arg);
-    
+
     return r;
 }
 
@@ -101,49 +97,51 @@
 {
     const char* ptr = (const char*)s;
     const char* end = ptr + length;
-    
-    while (ptr != end)
-    {
+
+    while (ptr != end) {
         _txbuf = *(ptr++);
     }
     BufferedSerial::prime();
-    
-    return ptr - (const char*)s;  
+
+    return ptr - (const char*)s;
 }
 
 
 void BufferedSerial::rxIrq(void)
 {
     // read from the peripheral and make sure something is available
-    if(serial_readable(&_serial))
-    {
+    if(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 fifo and if something is in the software fifo
-    while(serial_writable(&_serial) && _txbuf.available())
-    {
-        serial_putc(&_serial, (int)_txbuf.get());
+    while(serial_writable(&_serial)) {
+        if(_txbuf.available()) {
+            serial_putc(&_serial, (int)_txbuf.get());
+        } else {
+            // disable the TX interrupt when there is nothing left to send
+            Serial::attach(NULL, Serial::TxIrq);
+            break;
+        }
     }
-    
+
     return;
 }
 
 void BufferedSerial::prime(void)
 {
     // if already busy then the irq will pick this up
-    if(serial_writable(&_serial))
-    {
-        Serial::attach(NULL, Serial::TxIrq);    // make sure not to cause contention in the irq 
+    if(serial_writable(&_serial)) {
+        Serial::attach(NULL, Serial::TxIrq);    // make sure not to cause contention in the irq
         BufferedSerial::txIrq();                // only write to hardware in one place
         Serial::attach(this, &BufferedSerial::txIrq, Serial::TxIrq);
     }
-    
+
     return;
 }