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/* |
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Copyright 2012 Jun WAKO <[email protected]> |
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This software is licensed with a Modified BSD License. |
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All of this is supposed to be Free Software, Open Source, DFSG-free, |
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GPL-compatible, and OK to use in both free and proprietary applications. |
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Additions and corrections to this file are welcome. |
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Redistribution and use in source and binary forms, with or without |
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modification, are permitted provided that the following conditions are met: |
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* Redistributions of source code must retain the above copyright |
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notice, this list of conditions and the following disclaimer. |
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* Redistributions in binary form must reproduce the above copyright |
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notice, this list of conditions and the following disclaimer in |
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the documentation and/or other materials provided with the |
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distribution. |
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* Neither the name of the copyright holders nor the names of |
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contributors may be used to endorse or promote products derived |
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from this software without specific prior written permission. |
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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#include <stdbool.h> |
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#include <avr/io.h> |
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#include <avr/interrupt.h> |
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#include <util/delay.h> |
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#include "serial.h" |
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/* |
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* Stupid Inefficient Busy-wait Software Serial |
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* is still useful for negative logic signal like Sun protocol not supported by hardware USART. |
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*/ |
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#define WAIT_US (1000000/SERIAL_BAUD) |
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void serial_init(void) |
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{ |
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SERIAL_RXD_INIT(); |
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} |
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// RX ring buffer |
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#define RBUF_SIZE 8 |
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static uint8_t rbuf[RBUF_SIZE]; |
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static uint8_t rbuf_head = 0; |
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static uint8_t rbuf_tail = 0; |
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uint8_t serial_recv(void) |
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{ |
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uint8_t data = 0; |
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if (rbuf_head == rbuf_tail) { |
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return 0; |
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} |
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data = rbuf[rbuf_tail]; |
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rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE; |
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return data; |
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} |
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//ISR(INT2_vect) |
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ISR(SERIAL_RXD_VECT) |
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{ |
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SERIAL_RXD_INT_ENTER() |
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uint8_t data = 0; |
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#ifdef SERIAL_BIT_ORDER_MSB |
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uint8_t pos = 0x80; |
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#else |
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uint8_t pos = 0x01; |
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#endif |
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// to center of start bit |
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_delay_us(WAIT_US/2); |
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do { |
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// to center of next bit |
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_delay_us(WAIT_US); |
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if (SERIAL_RXD_PIN&(1<<SERIAL_RXD_BIT)) { |
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data |= pos; |
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} |
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#ifdef SERIAL_BIT_ORDER_MSB |
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pos >>= 1; |
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#else |
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pos <<= 1; |
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#endif |
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} while (pos); |
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// to center of stop bit |
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_delay_us(WAIT_US); |
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#ifdef SERIAL_NEGATIVE_LOGIC |
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data = ~data; |
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#endif |
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uint8_t next = (rbuf_head + 1) % RBUF_SIZE; |
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if (next != rbuf_tail) { |
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rbuf[rbuf_head] = data; |
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rbuf_head = next; |
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} |
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SERIAL_RXD_INT_EXIT(); |
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} |