Ross Squires / SoftSerial

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Fork of SoftSerial by Erik -

SoftSerial_rx.cpp@10:236fce2e5b8c, 2014-07-05 (annotated)

Committer:
Sissors
Date:
Sat Jul 05 13:22:43 2014 +0000
Revision:
10:236fce2e5b8c
Parent:
6:517082212c00 
Little bit faster initial read

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Sissors 0:8edaa7abe724 1 #include "SoftSerial.h"
Sissors 0:8edaa7abe724 2
Sissors 10:236fce2e5b8c 3 uint32_t overhead_us = 200 * 1000000 / SystemCoreClock; //Random estimation of the overhead of mbed libs, makes slow devices like LPC812 @ 12MHz perform better
Sissors 10:236fce2e5b8c 4
Sissors 0:8edaa7abe724 5 int SoftSerial::_getc( void ) {
Sissors 1:f8b4b764ace7 6 while(!readable());
Sissors 1:f8b4b764ace7 7 out_valid = false;
Sissors 1:f8b4b764ace7 8 return out_buffer;
Sissors 1:f8b4b764ace7 9 }
Sissors 0:8edaa7abe724 10
Sissors 1:f8b4b764ace7 11 int SoftSerial::readable(void) {
Sissors 1:f8b4b764ace7 12 return out_valid;
Sissors 1:f8b4b764ace7 13 }
Sissors 1:f8b4b764ace7 14
Sissors 1:f8b4b764ace7 15 //Start receiving byte
Sissors 0:8edaa7abe724 16 void SoftSerial::rx_gpio_irq_handler(void) {
Sissors 6:517082212c00 17 rxticker.prime();
Sissors 10:236fce2e5b8c 18 rxticker.setNext(bit_period + (bit_period >> 1) - overhead_us);
Sissors 1:f8b4b764ace7 19 rx->fall(NULL);
Sissors 1:f8b4b764ace7 20 rx_bit = 0;
Sissors 1:f8b4b764ace7 21 rx_error = false;
Sissors 0:8edaa7abe724 22 };
Sissors 1:f8b4b764ace7 23
Sissors 1:f8b4b764ace7 24 void SoftSerial::rx_handler(void) {
Sissors 10:236fce2e5b8c 25 //Receive data
Sissors 10:236fce2e5b8c 26 int val = rx->read();
Sissors 10:236fce2e5b8c 27
Sissors 6:517082212c00 28 rxticker.setNext(bit_period);
Sissors 1:f8b4b764ace7 29 rx_bit++;
Sissors 1:f8b4b764ace7 30
Sissors 10:236fce2e5b8c 31
Sissors 1:f8b4b764ace7 32 if (rx_bit <= _bits) {
Sissors 1:f8b4b764ace7 33 read_buffer |= val << (rx_bit - 1);
Sissors 1:f8b4b764ace7 34 return;
Sissors 1:f8b4b764ace7 35 }
Sissors 1:f8b4b764ace7 36
Sissors 1:f8b4b764ace7 37 //Receive parity
Sissors 1:f8b4b764ace7 38 bool parity_count;
Sissors 1:f8b4b764ace7 39 if (rx_bit == _bits + 1) {
Sissors 1:f8b4b764ace7 40 switch (_parity) {
Sissors 1:f8b4b764ace7 41 case Forced1:
Sissors 1:f8b4b764ace7 42 if (val == 0)
Sissors 1:f8b4b764ace7 43 rx_error = true;
Sissors 1:f8b4b764ace7 44 return;
Sissors 1:f8b4b764ace7 45 case Forced0:
Sissors 1:f8b4b764ace7 46 if (val == 1)
Sissors 1:f8b4b764ace7 47 rx_error = true;
Sissors 1:f8b4b764ace7 48 return;
Sissors 1:f8b4b764ace7 49 case Even:
Sissors 1:f8b4b764ace7 50 case Odd:
Sissors 1:f8b4b764ace7 51 parity_count = val;
Sissors 1:f8b4b764ace7 52 for (int i = 0; i<_bits; i++) {
Sissors 1:f8b4b764ace7 53 if (((read_buffer >> i) & 0x01) == 1)
Sissors 1:f8b4b764ace7 54 parity_count = !parity_count;
Sissors 1:f8b4b764ace7 55 }
Sissors 1:f8b4b764ace7 56 if ((parity_count) && (_parity == Even))
Sissors 1:f8b4b764ace7 57 rx_error = true;
Sissors 1:f8b4b764ace7 58 if ((!parity_count) && (_parity == Odd))
Sissors 1:f8b4b764ace7 59 rx_error = true;
Sissors 1:f8b4b764ace7 60 return;
Sissors 1:f8b4b764ace7 61 }
Sissors 1:f8b4b764ace7 62 }
Sissors 1:f8b4b764ace7 63
Sissors 1:f8b4b764ace7 64 //Receive stop
Sissors 1:f8b4b764ace7 65 if (rx_bit < _bits + (bool)_parity + _stop_bits) {
Sissors 1:f8b4b764ace7 66 if (!val)
Sissors 1:f8b4b764ace7 67 rx_error = true;
Sissors 1:f8b4b764ace7 68 return;
Sissors 1:f8b4b764ace7 69 }
Sissors 1:f8b4b764ace7 70
Sissors 1:f8b4b764ace7 71 //The last stop bit
Sissors 1:f8b4b764ace7 72 if (!val)
Sissors 1:f8b4b764ace7 73 rx_error = true;
Sissors 1:f8b4b764ace7 74
Sissors 1:f8b4b764ace7 75 if (!rx_error) {
Sissors 1:f8b4b764ace7 76 out_valid = true;
Sissors 1:f8b4b764ace7 77 out_buffer = read_buffer;
Sissors 4:c010265ed202 78 fpointer[RxIrq].call();
Sissors 1:f8b4b764ace7 79 }
Sissors 1:f8b4b764ace7 80 read_buffer = 0;
Sissors 3:7238e9bb74d2 81 rxticker.detach();
Sissors 1:f8b4b764ace7 82 rx->fall(this, &SoftSerial::rx_gpio_irq_handler);
Sissors 1:f8b4b764ace7 83 }
Sissors 1:f8b4b764ace7 84