skarg
396 lines
11 KiB
C
396 lines
11 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 "hardware.h"
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#include "mstp.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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static uint32_t RS485_Baud_Rate = 9600;
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// UART transmission buffer and index
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static volatile uint8_t RS485_Tx_Buffer[MAX_MPDU];
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static volatile uint8_t RS485_Tx_Index = 0;
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static volatile uint8_t RS485_Tx_Length = 0;
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static volatile char RS485_Tx_Postdrive_Delay = 0;
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static struct
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{
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unsigned TransmitStart:1; // TRUE if we are requested to transmit
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unsigned TransmitComplete:1; // TRUE if we are finished transmitting frame
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} RS485_Flags;
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// Duplicate of the RCSTA reg used due to the double buffering of the
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// fifo. Reading the RCREG reg will cause the second RCSTA reg to be
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// loaded if there is one. */
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struct _rcstabits
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{
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unsigned char RX9D:1;
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unsigned char OERR:1;
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unsigned char FERR:1;
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unsigned char ADDEN:1;
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unsigned char CREN:1;
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unsigned char SREN:1;
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unsigned char RX9:1;
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unsigned char SPEN:1;
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};
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volatile static enum
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{
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RS485_STATE_IDLE = 0,
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RS485_STATE_RX_DATA = 1,
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RS485_STATE_RX_CHECKSUM = 2,
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RS485_STATE_RX_PROCESS = 3,
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RS485_STATE_TX_DATA = 4,
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RS485_STATE_WAIT_FOR_ACK = 5,
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RS485_STATE_WAIT_COMPLETE = 6,
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RS485_STATE_TX_GLOBAL_ACK = 7,
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RS485_STATE_TX_POSTDRIVE_DELAY = 8,
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RS485_STATE_ERROR = 9,
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RS485_STATE_RX_TEST = 10,
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RS485_STATE_RX_TEST_EEPROM = 11,
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RS485_STATE_RX_TEST_DELAY = 12,
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RS485_STATE_TX_TEST_WAIT = 13,
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RS485_STATE_TX_TEST = 14
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} RS485_State;
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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) // number of bytes of data (up to 501)
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{
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// do we check for tx buffer in-use?
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// Or do we just stop the in-progress transmission?
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// Drop any transmission in progress, but don't worry about
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// cleaning up the hardware - the start routine will handle that
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// Disable the interrupt since it depends on the global transmit buffer.
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USART_TX_INT_DISABLE();
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switch (RS485_State)
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{
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case RS485_STATE_TX_DATA:
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case RS485_STATE_WAIT_FOR_ACK:
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case RS485_STATE_WAIT_COMPLETE:
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case RS485_STATE_TX_GLOBAL_ACK:
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RS485_State = RS485_STATE_IDLE;
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break;
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}
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// load the frame
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RS485_Tx_Length = 0;
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while (buffer && nbytes)
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{
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RS485_Tx_Buffer[RS485_Tx_Length] = *buffer;
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buffer++;
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nbytes--;
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RS485_Tx_Length++;
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// check bounds - should this error be indicated somehow?
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// perhaps not send the message?
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if (RS485_Tx_Length >= MAX_MPDU)
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break;
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}
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// signal the task to start sending when it is ready
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RS485_Flags.TransmitStart = TRUE;
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return;
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}
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/****************************************************************************
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* DESCRIPTION: Processes the next RS485 byte for transmit
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* RETURN: none
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* ALGORITHM: none
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* NOTES: Called by interrupt service routine (ISR)
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*****************************************************************************/
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void RS485_Transmit_Interrupt(void)
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{
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uint8_t data; // data byte to send
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switch (RS485_State)
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{
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case RS485_STATE_TX_DATA:
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RS485_Tx_Index++;
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if (RS485_Tx_Index < RS485_Tx_Length)
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{
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data = RS485_Tx_Buffer[RS485_Tx_Index];
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USART_TRANSMIT(data);
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MSTP_Port.SilenceTimer = 0;
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}
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else
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{
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// wait until the last bit is sent
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while (!USART_TX_EMPTY());
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RS485_TRANSMIT_DISABLE();
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// wait 2 characters after sending (min=15 bit times)
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RS485_Tx_Postdrive_Delay = 2;
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RS485_State = RS485_STATE_TX_POSTDRIVE_DELAY;
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USART_TRANSMIT(0);
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}
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break;
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case RS485_STATE_TX_POSTDRIVE_DELAY:
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// after the message is sent, we wait a certain
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// number of character times to get a delay
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if (RS485_Tx_Postdrive_Delay)
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{
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RS485_Tx_Postdrive_Delay--;
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if (RS485_Tx_Postdrive_Delay == 0)
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RS485_State = RS485_STATE_WAIT_COMPLETE;
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USART_TRANSMIT(0);
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}
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else
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RS485_State = RS485_STATE_WAIT_COMPLETE;
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break;
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case RS485_STATE_WAIT_COMPLETE:
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// wait until the last delay bit is shifted
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while (!USART_TX_EMPTY());
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USART_TX_INT_DISABLE();
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RS485_Flags.TransmitComplete = TRUE;
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RS485_State = RS485_STATE_IDLE;
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USART_RX_SETUP();
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break;
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default:
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break;
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}
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return;
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}
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/****************************************************************************
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* DESCRIPTION: Processes the RS485 message to be 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_Process_Tx_Message(void)
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{
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if (RS485_Flags.TransmitComplete)
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RS485_Flags.TransmitComplete = FALSE;
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// start a new transmisstion if we are ready
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if (RS485_Flags.TransmitStart && (RS485_State == RS485_STATE_IDLE))
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{
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// Disable the receiver
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USART_RX_INT_DISABLE();
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USART_CONTINUOUS_RX_DISABLE();
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// Enable the transmit line driver and interrupts
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RS485_TRANSMIT_ENABLE();
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RS485_State = RS485_STATE_TX_DATA;
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// Configure the ISR handler for an outgoing message
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RS485_Tx_Index = 0;
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// update the flags for beginning a send
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RS485_Flags.TransmitComplete = FALSE;
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RS485_Flags.TransmitStart = FALSE;
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// send the first byte
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USART_TRANSMIT(RS485_Tx_Buffer[0]);
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USART_TX_SETUP();
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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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void RS485_Check_UART_Data(volatile struct mstp_port_struct_t *mstp_port)
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{
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struct _rcstabits rcstabits; // reading it more than once gets wrong data
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// check for data
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if (USART_RX_COMPLETE())
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{
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// Read the data and the Rx status reg
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rcstabits = USART_RX_STATUS();
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mstp_port->DataRegister = USART_RECEIVE();
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// Check for buffer overrun error
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if (rcstabits.OERR)
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{
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// clear the error
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USART_CONTINUOUS_RX_DISABLE();
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USART_CONTINUOUS_RX_ENABLE();
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// let the state machine know
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mstp_port->ReceiveError = TRUE;
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}
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// Check for framing errors
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else if (USART_RX_FRAME_ERROR())
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{
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// let the state machine know
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mstp_port->FramingError = TRUE;
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mstp_port->ReceiveError = TRUE;
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}
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// We read a good byte
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else
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{
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// state machine will clear this
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mstp_port->DataAvailable = TRUE;
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}
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}
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return;
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}
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/****************************************************************************
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* DESCRIPTION: Receives a data byte from the 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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void RS485_Receive_Interrupt(void)
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{
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// get as many bytes as we can get
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for (;;)
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{
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RS485_Check_UART_Data(&MSTP_Port);
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if (MSTP_Port.ReceiveError || MSTP_Port.DataAvailable)
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MSTP_Receive_Frame_FSM(&MSTP_Port);
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else
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break;
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}
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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(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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void RS485_Set_Baud_Rate(uint32_t baud)
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{
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if (baud < 19200)
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RS485_Baud_Rate = 9600;
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else if (baud < 38400)
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RS485_Baud_Rate = 19200;
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else if (baud < 57600)
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RS485_Baud_Rate = 38400;
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else if (baud < 57600)
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RS485_Baud_Rate = 57600;
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else if (baud < 115200)
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RS485_Baud_Rate = 76800;
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else
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RS485_Baud_Rate = 115200;
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}
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void RS485_Initialize_Baud(void)
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{
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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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{
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case 19200:
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SPBRG = 64;
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TXSTAbits.BRGH=1;
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break;
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case 38400:
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SPBRG = 32;
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TXSTAbits.BRGH=1;
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break;
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case 57600:
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SPBRG = 21;
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TXSTAbits.BRGH=1;
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break;
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case 76800:
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SPBRG = 3;
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TXSTAbits.BRGH=0;
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break;
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case 115200:
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SPBRG = 10;
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TXSTAbits.BRGH=1;
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break;
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case 9600:
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default:
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SPBRG = 129;
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TXSTAbits.BRGH=1;
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break;
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}
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/* select async mode */
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TXSTAbits.SYNC=0;
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/* serial port enable */
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RCSTAbits.SPEN=1;
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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(void)
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{
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RS485_Initialize_Baud();
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/* configure interrupts */
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USART_TX_INT_DISABLE();
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USART_RX_INT_ENABLE();
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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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USART_CONTINUOUS_RX_ENABLE();
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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_TRANSMIT_DISABLE();
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}
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