mirror of
https://github.com/stargieg/bacnet-stack
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242 lines
7.5 KiB
C
242 lines
7.5 KiB
C
/**************************************************************************
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*
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* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
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* RS-485 initialization on AT91SAM7S inspired by Keil Eletronik serial.c
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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 "timer.h"
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/* This file has been customized for use with DOS */
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#include <dos.h>
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#include "serial.h"
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/* UART */
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static char RS485_Port = '2';
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/* baud rate */
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static int RS485_Baud = 38400;
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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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/* baud rate */
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OpenComPort(RS485_Port);
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/* FIXME: change to numeric parameters */
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InitComPort("38400", '8', 'N', '1');
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return;
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}
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void RS485_Cleanup(
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void)
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{
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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: none
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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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/* 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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uint16_t turnaround_time;
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/* delay after reception before trasmitting - per MS/TP spec */
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/* wait a minimum 40 bit times since reception */
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/* at least 1 ms for errors: rounding, clock tick */
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turnaround_time = 1 + ((Tturnaround * 1000UL) / RS485_Baud);
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while (Timer_Silence() < turnaround_time) {
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/* do nothing - wait for timer to increment */
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};
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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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(void) enable;
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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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/* send all the bytes */
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ComSendData(buffer, nbytes);
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while (!(RS485_Interface->US_CSR & AT91C_US_TXRDY)) {
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/* do nothing - wait until Tx buffer is empty */
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}
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/* per MSTP spec */
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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: none
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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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/* LED on send */
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volatile AT91PS_PIO pPIO = AT91C_BASE_PIOA;
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/* check for data or error */
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if (RS485_Interface->US_CSR & (AT91C_US_OVRE | AT91C_US_FRAME)) {
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/* clear the error flag */
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RS485_Interface->US_CR = AT91C_US_RSTSTA;
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ReceiveError = true;
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/* LED ON */
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pPIO->PIO_CODR = LED2;
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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 * DataRegister)
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{
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bool DataAvailable = false;
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/* LED on send */
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volatile AT91PS_PIO pPIO = AT91C_BASE_PIOA;
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if (RS485_Interface->US_CSR & AT91C_US_RXRDY) {
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/* data is available */
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*DataRegister = RS485_Interface->US_RHR;
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DataAvailable = true;
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/* LED ON */
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pPIO->PIO_CODR = LED2;
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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
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