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);
     }
 }

Files at this revision

API Documentation at this revision

Revision 3:6b76fcf27545, committed 2013-06-12

Comitter:
sam_grove
Date:
Wed Jun 12 20:40:15 2013 +0000
Parent:
2:7e8a450a9101
Child:
4:2ba4d2e1f05d
Commit message:
Updates to block only tx irq when fifo needs a kick. Updated comments and documentation

Changed in this revision

BufferedSerial.cpp Show annotated file Show diff for this revision Revisions of this file
BufferedSerial.h Show annotated file Show diff for this revision Revisions of this file 
--- a/BufferedSerial.cpp	Fri May 24 22:00:26 2013 +0000
+++ b/BufferedSerial.cpp	Wed Jun 12 20:40:15 2013 +0000
@@ -53,7 +53,7 @@
 
 int BufferedSerial::getc(void)
 {
-    return _rxbuf;   // note: pulling from the buffer
+    return _rxbuf;
 }
 
 int BufferedSerial::putc(int c)
@@ -114,7 +114,7 @@
 
 void BufferedSerial::rxIrq(void)
 {
-    // read from the peripheral and see if things are available
+    // read from the peripheral and make sure something is available
     if(serial_readable(&_serial))
     {
         _rxbuf = serial_getc(&_serial); // if so load them into a buffer
@@ -125,8 +125,8 @@
 
 void BufferedSerial::txIrq(void)
 {
-    // see if there is room in the hardware buffer and something is in the software buffer
-    if(serial_writable(&_serial) && _txbuf.available())
+    // 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());
     }
@@ -139,9 +139,9 @@
     // if already busy then the irq will pick this up
     if(serial_writable(&_serial))
     {
-        __disable_irq();    // make sure not to cause contention in the irq 
-        BufferedSerial::txIrq();    // prime the txirq - only write to hardware in one place
-        __enable_irq();
+        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;

--- a/BufferedSerial.h	Fri May 24 22:00:26 2013 +0000
+++ b/BufferedSerial.h	Wed Jun 12 20:40:15 2013 +0000
@@ -73,8 +73,8 @@
 class BufferedSerial : public Serial 
 {
 private:
-    Buffer <char>   _rxbuf;
-    Buffer <char>   _txbuf;
+    Buffer <char> _rxbuf;
+    Buffer <char> _txbuf;
  
     void rxIrq(void);
     void txIrq(void);