Erik - / SoftSerial

Software serial, for when you are out of serial pins

Dependents:   BufferedSoftSerial neurGAI_Seeed_BLUETOOTH LPC-SD-35 ESP-WROOM-02_test ... more

SoftSerial_tx.cpp@8:332b66de89d3, 2014-04-27 (annotated)

Committer:
Sissors
Date:
Sun Apr 27 19:48:40 2014 +0000
Revision:
8:332b66de89d3
Parent:
7:7de3e1019e23 
And to be sure it calculates correctly

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Sissors 0:8edaa7abe724 1 #include "SoftSerial.h"
Sissors 0:8edaa7abe724 2
Sissors 2:9e01a38606b4 3 int SoftSerial::_putc(int c)
Sissors 2:9e01a38606b4 4 {
Sissors 0:8edaa7abe724 5 while(!writeable());
Sissors 2:9e01a38606b4 6 prepare_tx(c);
Sissors 0:8edaa7abe724 7 tx_bit = 0;
Sissors 6:517082212c00 8 txticker.prime();
Sissors 0:8edaa7abe724 9 tx_handler();
Sissors 0:8edaa7abe724 10 return 0;
Sissors 2:9e01a38606b4 11 }
Sissors 0:8edaa7abe724 12
Sissors 7:7de3e1019e23 13 void SoftSerial::send_break(void) {
Sissors 7:7de3e1019e23 14 while(!writeable());
Sissors 7:7de3e1019e23 15 tx_bit = 0; //Just to make sure it appears as non-writable to other threads/IRQs
Sissors 7:7de3e1019e23 16 tx->write(0);
Sissors 8:332b66de89d3 17 wait_us((bit_period * _total_bits * 3) / 2);
Sissors 7:7de3e1019e23 18 tx->write(1);
Sissors 7:7de3e1019e23 19 tx_bit = -1;
Sissors 7:7de3e1019e23 20 }
Sissors 7:7de3e1019e23 21
Sissors 2:9e01a38606b4 22 int SoftSerial::writeable(void)
Sissors 2:9e01a38606b4 23 {
Sissors 0:8edaa7abe724 24 if (!tx_en)
Sissors 0:8edaa7abe724 25 return false;
Sissors 0:8edaa7abe724 26 if (tx_bit == -1)
Sissors 0:8edaa7abe724 27 return true;
Sissors 0:8edaa7abe724 28 return false;
Sissors 0:8edaa7abe724 29 }
Sissors 0:8edaa7abe724 30
Sissors 2:9e01a38606b4 31 void SoftSerial::tx_handler(void)
Sissors 2:9e01a38606b4 32 {
Sissors 2:9e01a38606b4 33 if (tx_bit == _total_bits) {
Sissors 0:8edaa7abe724 34 tx_bit = -1;
Sissors 4:c010265ed202 35 fpointer[TxIrq].call();
Sissors 0:8edaa7abe724 36 return;
Sissors 0:8edaa7abe724 37 }
Sissors 2:9e01a38606b4 38
Sissors 0:8edaa7abe724 39 //Flip output
Sissors 0:8edaa7abe724 40 int cur_out = tx->read();
Sissors 0:8edaa7abe724 41 tx->write(!cur_out);
Sissors 2:9e01a38606b4 42
Sissors 0:8edaa7abe724 43 //Calculate when to do it again
Sissors 0:8edaa7abe724 44 int count = bit_period;
Sissors 0:8edaa7abe724 45 tx_bit++;
Sissors 2:9e01a38606b4 46 while(((_char >> tx_bit) & 0x01) == !cur_out) {
Sissors 0:8edaa7abe724 47 count+=bit_period;
Sissors 0:8edaa7abe724 48 tx_bit++;
Sissors 0:8edaa7abe724 49 }
Sissors 2:9e01a38606b4 50
Sissors 6:517082212c00 51 txticker.setNext(count);
Sissors 0:8edaa7abe724 52 }
Sissors 0:8edaa7abe724 53
Sissors 2:9e01a38606b4 54 void SoftSerial::prepare_tx(int c)
Sissors 2:9e01a38606b4 55 {
Sissors 2:9e01a38606b4 56 _char = c << 1;
Sissors 2:9e01a38606b4 57
Sissors 2:9e01a38606b4 58 bool parity;
Sissors 2:9e01a38606b4 59 switch (_parity) {
Sissors 2:9e01a38606b4 60 case Forced1:
Sissors 2:9e01a38606b4 61 _char |= 1 << (_bits + 1);
Sissors 2:9e01a38606b4 62 case Even:
Sissors 2:9e01a38606b4 63 parity = false;
Sissors 2:9e01a38606b4 64 for (int i = 0; i<_bits; i++) {
Sissors 2:9e01a38606b4 65 if (((_char >> i) & 0x01) == 1)
Sissors 2:9e01a38606b4 66 parity = !parity;
Sissors 2:9e01a38606b4 67 }
Sissors 2:9e01a38606b4 68 _char |= parity << (_bits + 1);
Sissors 2:9e01a38606b4 69 case Odd:
Sissors 2:9e01a38606b4 70 parity = true;
Sissors 2:9e01a38606b4 71 for (int i = 0; i<_bits; i++) {
Sissors 2:9e01a38606b4 72 if (((_char >> i) & 0x01) == 1)
Sissors 2:9e01a38606b4 73 parity = !parity;
Sissors 2:9e01a38606b4 74 }
Sissors 2:9e01a38606b4 75 _char |= parity << (_bits + 1);
Sissors 0:8edaa7abe724 76 }
Sissors 0:8edaa7abe724 77
Sissors 2:9e01a38606b4 78 _char |= 0xFFFF << (1 + _bits + (bool)_parity);
Sissors 2:9e01a38606b4 79 _char &= ~(1<<_total_bits);
Sissors 2:9e01a38606b4 80 }