SoftSerial_rx.cpp

00001 #include "SoftSerial.h"
00002 
00003 uint32_t overhead_us = 200 * 1000000 / SystemCoreClock;         //Random estimation of the overhead of mbed libs, makes slow devices like LPC812 @ 12MHz perform better
00004 
00005 int SoftSerial::_getc( void ) {
00006     while(!readable());
00007     out_valid = false;
00008     return out_buffer;
00009 }
00010 
00011 int SoftSerial::readable(void) {
00012     return out_valid;
00013 }
00014 
00015 //Start receiving byte
00016 void SoftSerial::rx_gpio_irq_handler(void) {
00017     rxticker.prime();
00018     rxticker.setNext(bit_period + (bit_period >> 1) - overhead_us);
00019     rx->fall(NULL);
00020     rx_bit = 0;
00021     rx_error = false;
00022 };    
00023 
00024 void SoftSerial::rx_handler(void) {
00025     //Receive data
00026     int val = rx->read();
00027  
00028     rxticker.setNext(bit_period);
00029     rx_bit++;
00030     
00031     
00032     if (rx_bit <= _bits) {
00033         read_buffer |= val << (rx_bit - 1);
00034         return;
00035     }
00036     
00037     //Receive parity
00038     bool parity_count;
00039     if (rx_bit == _bits + 1) {
00040         switch (_parity) {
00041             case Forced1:
00042                 if (val == 0)
00043                     rx_error = true;
00044                 return;
00045             case Forced0:
00046                 if (val == 1)
00047                     rx_error = true;
00048                 return;
00049             case Even:
00050             case Odd:
00051                 parity_count = val;
00052                 for (int i = 0; i<_bits; i++) {
00053                     if (((read_buffer >> i) & 0x01) == 1)
00054                         parity_count = !parity_count;
00055                 }
00056                 if ((parity_count) && (_parity == Even))
00057                     rx_error = true;
00058                 if ((!parity_count) && (_parity == Odd))
00059                     rx_error = true;
00060                 return;
00061         }
00062     }
00063     
00064     //Receive stop
00065     if (rx_bit < _bits + (bool)_parity + _stop_bits) {
00066         if (!val)
00067             rx_error = true;
00068         return;
00069     }    
00070     
00071     //The last stop bit
00072     if (!val)
00073         rx_error = true;
00074     
00075     if (!rx_error) {
00076         out_valid = true;
00077         out_buffer = read_buffer;
00078         fpointer[RxIrq].call();
00079     }
00080     read_buffer = 0;
00081     rxticker.detach(); 
00082     rx->fall(this, &SoftSerial::rx_gpio_irq_handler);
00083 }
00084