mirror of
https://github.com/stargieg/bacnet-stack
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354 lines
10 KiB
C
354 lines
10 KiB
C
/**************************************************************************
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*
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* Copyright (C) 2005 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 <string.h>
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#include "hardware.h"
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#include "mstp.h"
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#include "rs485.h"
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#include "fifo.h"
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/* public port info */
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extern volatile struct mstp_port_struct_t MSTP_Port;
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/* the baud rate is adjustable */
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uint32_t RS485_Baud_Rate = 38400;
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/* the FIFO structures for sending and receiving */
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FIFO_BUFFER FIFO_Rx;
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FIFO_BUFFER FIFO_Tx;
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#pragma udata MSTPPortData
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/* the buffer for receiving data (size must be a power of 2) */
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volatile uint8_t RS485_Rx_Buffer[128];
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/* the buffer for sending data (size must be a power of 2) */
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volatile uint8_t RS485_Tx_Buffer[128];
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#pragma udata
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/****************************************************************************
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* DESCRIPTION: Transmits a frame using the UART
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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_Frame(
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volatile struct mstp_port_struct_t *mstp_port, /* port specific data */
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uint8_t * buffer, /* frame to send (up to 501 bytes of data) */
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uint16_t nbytes)
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{ /* number of bytes of data (up to 501) */
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uint16_t i = 0; /* loop counter */
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uint8_t turnaround_time;
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if (!buffer)
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return;
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while (!FIFO_Empty(&FIFO_Tx)) {
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/* buffer is not empty. Wait for ISR to transmit. */
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};
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/* wait 40 bit times since reception */
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if (RS485_Baud_Rate == 9600)
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turnaround_time = 4;
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else if (RS485_Baud_Rate == 19200)
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turnaround_time = 2;
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else
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turnaround_time = 2;
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while (mstp_port->SilenceTimer < turnaround_time) {
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/* The line has not been silent long enough, so wait. */
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};
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if (FIFO_Add(&FIFO_Tx, buffer, nbytes)) {
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/* disable the receiver */
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PIE3bits.RC2IE = 0;
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RCSTA2bits.CREN = 0;
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/* enable the transceiver */
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RS485_TX_ENABLE = 1;
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RS485_RX_DISABLE = 1;
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/* enable the transmitter */
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TXSTA2bits.TXEN = 1;
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PIE3bits.TX2IE = 1;
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/* reset the silence timer per MSTP spec, sort of */
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mstp_port->SilenceTimer = 0;
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}
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return;
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}
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/****************************************************************************
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* DESCRIPTION: Checks for data on the receive UART, and handles errors
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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_Check_UART_Data(
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volatile struct mstp_port_struct_t * mstp_port)
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{
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/* check for data */
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if (!FIFO_Empty(&FIFO_Rx)) {
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mstp_port->DataRegister = FIFO_Get(&FIFO_Rx);
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mstp_port->DataAvailable = TRUE;
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}
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return (!FIFO_Empty(&FIFO_Rx));
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}
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/* *************************************************************************
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DESCRIPTION: Receives RS485 data stream
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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_Interrupt_Rx(
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void)
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{
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uint8_t data_byte;
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if ((RCSTA2bits.FERR) || (RCSTA2bits.OERR)) {
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/* Clear the error */
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RCSTA2bits.CREN = 0;
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RCSTA2bits.CREN = 1;
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/* FIXME: flag the MS/TP state machine on buffer overrun */
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data_byte = RCREG2;
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} else {
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data_byte = RCREG2;
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FIFO_Put(&FIFO_Rx, data_byte);
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}
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}
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/* *************************************************************************
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DESCRIPTION: Transmits a byte using the UART out the RS485 port
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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_Interrupt_Tx(
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void)
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{
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if (!FIFO_Empty(&FIFO_Tx)) {
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TXREG2 = FIFO_Get(&FIFO_Tx);
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} else {
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/* wait for the USART to be empty */
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while (!TXSTA2bits.TRMT);
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/* disable this interrupt */
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PIE3bits.TX2IE = 0;
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/* enable the receiver */
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RS485_TX_ENABLE = 0;
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RS485_RX_DISABLE = 0;
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/* enable the this interrupt */
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PIE3bits.RC2IE = 1;
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RCSTA2bits.CREN = 1;
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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_Rate;
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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_Rate = baud;
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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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if (valid) {
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/* FIXME: store the baud rate */
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/* I2C_Write_Block(
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EEPROM_DEVICE_ADDRESS,
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(char *)&RS485_Baud_Rate,
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sizeof(RS485_Baud_Rate),
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EEPROM_MSTP_BAUD_RATE_ADDR); */
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}
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return valid;
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}
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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_Port(
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void)
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{
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/* Reset USART registers to POR state */
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TXSTA2 = 0;
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RCSTA2 = 0;
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/* configure USART for receiving */
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/* since the TX will handle setting up for transmit */
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RCSTA2bits.CREN = 1;
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/* Interrupt on receipt */
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PIE3bits.RC2IE = 1;
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/* enable the transmitter, disable its interrupt */
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TXSTA2bits.TXEN = 1;
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PIE3bits.TX2IE = 0;
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/* setup USART Baud Rate Generator */
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/* see BAUD RATES FOR ASYNCHRONOUS MODE in Data Book */
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/* Fosc=20MHz
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BRGH=1 BRGH=0
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Rate SPBRG Rate SPBRG
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------- ----- ------- -----
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9615 129 9469 32
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19230 64 19530 15
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37878 32 78130 3
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56818 21 104200 2
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113630 10 312500 0
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250000 4
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625000 1
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1250000 0
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*/
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switch (RS485_Baud_Rate) {
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case 19200:
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SPBRG2 = 64;
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TXSTA2bits.BRGH = 1;
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break;
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case 38400:
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SPBRG2 = 32;
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TXSTA2bits.BRGH = 1;
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break;
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case 57600:
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SPBRG2 = 21;
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TXSTA2bits.BRGH = 1;
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break;
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case 76800:
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SPBRG2 = 3;
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TXSTA2bits.BRGH = 0;
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break;
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case 115200:
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SPBRG2 = 10;
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TXSTA2bits.BRGH = 1;
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break;
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case 9600:
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SPBRG2 = 129;
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TXSTA2bits.BRGH = 1;
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break;
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default:
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SPBRG2 = 129;
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TXSTA2bits.BRGH = 1;
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RS485_Set_Baud_Rate(9600);
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break;
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}
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/* select async mode */
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TXSTA2bits.SYNC = 0;
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/* enable transmitter */
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TXSTA2bits.TXEN = 1;
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/* serial port enable */
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RCSTA2bits.SPEN = 1;
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/* since we are using RS485,
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we need to explicitly say
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transmit enable or not */
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RS485_RX_DISABLE = 0;
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RS485_TX_ENABLE = 0;
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}
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/****************************************************************************
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* DESCRIPTION: Disables the RS485 hardware
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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_Disable_Port(
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void)
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{
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RCSTA2 &= 0x4F; /* Disable the receiver */
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TXSTA2bits.TXEN = 0; /* and transmitter */
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PIE3 &= 0xCF; /* Disable both interrupts */
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}
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/****************************************************************************
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* DESCRIPTION: Reinitializes the port
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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_Reinit(
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void)
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{
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RS485_Set_Baud_Rate(38400);
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}
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/****************************************************************************
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* DESCRIPTION: Initializes the data and the port
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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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/* Init the Rs485 buffers */
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FIFO_Init(&FIFO_Rx, RS485_Rx_Buffer, sizeof(RS485_Rx_Buffer));
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FIFO_Init(&FIFO_Tx, RS485_Tx_Buffer, sizeof(RS485_Tx_Buffer));
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/* FIXME: read the stored baud rate */
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/* I2C_Read_Block(
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EEPROM_DEVICE_ADDRESS,
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(char *)&RS485_Baud_Rate,
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sizeof(RS485_Baud_Rate),
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EEPROM_MSTP_BAUD_RATE_ADDR); */
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RS485_Initialize_Port();
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}
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