mirror of
https://github.com/stargieg/bacnet-stack
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fork from http://sourceforge.net/projects/bacnet/
This commit is contained in:
Patrick Grimm
301
ports/atmega8/rs485.c
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301
ports/atmega8/rs485.c
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/**************************************************************************
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*
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* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*********************************************************************/
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/* The module handles sending data out the RS-485 port */
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/* and handles receiving data from the RS-485 port. */
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/* Customize this file for your specific hardware */
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#include <stddef.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <stdio.h>
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/*#include "mstp.h" */
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/* This file has been customized for use with ATMEGA168 */
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#if defined(__AVR_ATmega168__)
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/* USART defines for RS-485 port */
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#define UCSRB UCSR0B
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#define TXEN TXEN0
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#define RXEN RXEN0
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#define UCSRC UCSR0C
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#define UCSZ1 UCSZ01
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#define UCSZ0 UCSZ00
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#define UCSRA UCSR0A
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#define U2X U2X0
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#define UBRRL UBRR0
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#define UCSRA UCSR0A
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#define UDRE UDRE0
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#define UDR UDR0
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#define TXC TXC0
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#define FE FE0
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#define DOR DOR0
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#define UPE UPE0
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#define DOR DOR0
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#define RXC RXC0
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#endif
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#include "hardware.h"
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#include "timer.h"
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/* baud rate */
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static uint32_t RS485_Baud;
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/* The minimum time after the end of the stop bit of the final octet of a */
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/* received frame before a node may enable its EIA-485 driver: 40 bit times. */
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/* At 9600 baud, 40 bit times would be about 4.166 milliseconds */
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/* At 19200 baud, 40 bit times would be about 2.083 milliseconds */
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/* At 38400 baud, 40 bit times would be about 1.041 milliseconds */
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/* At 57600 baud, 40 bit times would be about 0.694 milliseconds */
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/* At 76800 baud, 40 bit times would be about 0.520 milliseconds */
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/* At 115200 baud, 40 bit times would be about 0.347 milliseconds */
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/* 40 bits is 4 octets including a start and stop bit with each octet */
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#define Tturnaround (40UL)
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/* turnaround_time_milliseconds = (Tturnaround*1000UL)/RS485_Baud; */
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/****************************************************************************
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* DESCRIPTION: Initializes the RS485 hardware and variables, and starts in
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* receive mode.
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* RETURN: none
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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void RS485_Initialize(
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void)
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{
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/* enable Transmit and Receive */
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UCSRB = _BV(TXEN) | _BV(RXEN);
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/* Set USART Control and Status Register n C */
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/* Asynchronous USART 8-bit data, No parity, 1 stop */
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/* Set USART Mode Select: UMSELn1 UMSELn0 = 00 for Asynchronous USART */
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/* Set Parity Mode: UPMn1 UPMn0 = 00 for Parity Disabled */
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/* Set Stop Bit Select: USBSn = 0 for 1 stop bit */
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/* Set Character Size: UCSZn2 UCSZn1 UCSZn0 = 011 for 8-bit */
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/* Clock Polarity: UCPOLn = 0 when asynchronous mode is used. */
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UCSRC = _BV(UCSZ1) | _BV(UCSZ0);
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#if defined(__AVR_ATmega168__)
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/* Clear Power Reduction USART0 */
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BIT_CLEAR(PRR, PRUSART0);
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#endif
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/* Use port PD2 for RTS - enable and disable of Transceiver Tx/Rx */
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/* Set port bit as Output - initially receiving */
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BIT_CLEAR(PORTD, PD2);
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BIT_SET(DDRD, DDD2);
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return;
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}
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/****************************************************************************
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* DESCRIPTION: Returns the baud rate that we are currently running at
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* RETURN: none
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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uint32_t RS485_Get_Baud_Rate(
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void)
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{
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return RS485_Baud;
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}
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/****************************************************************************
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* DESCRIPTION: Sets the baud rate for the chip USART
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* RETURN: true if valid baud rate
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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bool RS485_Set_Baud_Rate(
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uint32_t baud)
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{
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bool valid = true;
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switch (baud) {
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case 9600:
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case 19200:
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case 38400:
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case 57600:
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case 76800:
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case 115200:
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RS485_Baud = baud;
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/* 2x speed mode */
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BIT_SET(UCSRA, U2X);
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/* configure baud rate */
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UBRRL = (F_CPU / (8UL * RS485_Baud)) - 1;
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/* FIXME: store the baud rate */
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break;
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default:
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valid = false;
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break;
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}
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return valid;
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}
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/****************************************************************************
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* DESCRIPTION: Waits on the SilenceTimer for 40 bits.
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* RETURN: none
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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void RS485_Turnaround_Delay(
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void)
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{
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uint8_t nbytes = 4;
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RS485_Transmitter_Enable(false);
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while (nbytes) {
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while (!BIT_CHECK(UCSR0A, UDRE0)) {
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/* do nothing - wait until Tx buffer is empty */
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}
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/* Send the data byte */
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UDR0 = 0xff;
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nbytes--;
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}
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/* was the frame sent? */
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while (!BIT_CHECK(UCSR0A, TXC0)) {
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/* do nothing - wait until the entire frame in the
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Transmit Shift Register has been shifted out */
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}
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/* Clear the Transmit Complete flag by writing a one to it. */
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BIT_SET(UCSR0A, TXC0);
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}
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/****************************************************************************
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* DESCRIPTION: Enable or disable the transmitter
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* RETURN: none
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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void RS485_Transmitter_Enable(
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bool enable)
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{
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if (enable) {
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BIT_SET(PORTD, PD2);
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} else {
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BIT_CLEAR(PORTD, PD2);
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}
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}
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/****************************************************************************
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* DESCRIPTION: Send some data and wait until it is sent
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* RETURN: none
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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void RS485_Send_Data(
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uint8_t * buffer, /* data to send */
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uint16_t nbytes)
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{ /* number of bytes of data */
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while (nbytes) {
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while (!BIT_CHECK(UCSRA, UDRE)) {
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/* do nothing - wait until Tx buffer is empty */
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}
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/* Send the data byte */
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UDR = *buffer;
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buffer++;
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nbytes--;
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}
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/* was the frame sent? */
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while (!BIT_CHECK(UCSRA, TXC)) {
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/* do nothing - wait until the entire frame in the
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Transmit Shift Register has been shifted out */
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}
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/* Clear the Transmit Complete flag by writing a one to it. */
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BIT_SET(UCSRA, TXC);
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/* per MSTP spec, sort of */
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timer_silence_reset();
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}
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/****************************************************************************
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* DESCRIPTION: Return true if a framing or overrun error is present
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* RETURN: true if error
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* ALGORITHM: autobaud - if there are a lot of errors, switch baud rate
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* NOTES: Clears any error flags.
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*****************************************************************************/
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bool RS485_ReceiveError(
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void)
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{
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bool ReceiveError = false;
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uint8_t dummy_data;
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/* check for framing error */
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#if 0
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if (BIT_CHECK(UCSRA, FE0)) {
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/* FIXME: how do I clear the error flags? */
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BITMASK_CLEAR(UCSRA, (_BV(FE) | _BV(DOR) | _BV(UPE)));
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ReceiveError = true;
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}
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#endif
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/* check for overrun error */
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if (BIT_CHECK(UCSRA, DOR)) {
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/* flush the receive buffer */
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do {
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dummy_data = UDR;
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} while (BIT_CHECK(UCSRA, RXC));
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ReceiveError = true;
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}
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return ReceiveError;
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}
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/****************************************************************************
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* DESCRIPTION: Return true if data is available
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* RETURN: true if data is available, with the data in the parameter set
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* ALGORITHM: none
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* NOTES: none
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*****************************************************************************/
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bool RS485_DataAvailable(
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uint8_t * data)
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{
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bool DataAvailable = false;
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/* check for data */
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if (BIT_CHECK(UCSRA, RXC)) {
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*data = UDR;
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DataAvailable = true;
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}
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return DataAvailable;
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}
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#ifdef TEST_RS485
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int main(
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void)
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{
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unsigned i = 0;
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uint8_t DataRegister;
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RS485_Set_Baud_Rate(38400);
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RS485_Initialize();
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/* receive task */
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for (;;) {
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if (RS485_ReceiveError()) {
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fprintf(stderr, "ERROR ");
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} else if (RS485_DataAvailable(&DataRegister)) {
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fprintf(stderr, "%02X ", DataRegister);
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}
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}
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}
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#endif /* TEST_RS485 */
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