Rewrote MS/TP to minimize memory usage. Compiles, but untested.

bacnet-stack/ports/atmega168/Makefile

@@ -20,7 +20,6 @@ CSRC = main.c \
 	../../npdu.c \
 	../../bacint.c \
 	../../bacaddr.c \
-	../../mstp.c \
 	../../crc.c
 
 DEMOSRC = h_rp.c \

bacnet-stack/ports/atmega168/main.c

@@ -117,7 +117,7 @@ int main(void)
         task_milliseconds();
         /* other tasks */
         /* BACnet handling */
-        pdu_len = datalink_receive(&src, &PDUBuffer[0], MAX_MPDU, 0);
+        pdu_len = datalink_receive(&src, &PDUBuffer[0], sizeof(PDUBuffer), 0);
         if (pdu_len) {
             //npdu_handler(&src, &PDUBuffer[0], pdu_len);
         }

bacnet-stack/ports/atmega168/rs485.c

@@ -35,10 +35,23 @@
 
 /* This file has been customized for use with ATMEGA168 */
 #include "hardware.h"
+#include "timer.h"
 
 /* baud rate */
 static uint32_t RS485_Baud = 38400;
 
+/* The minimum time after the end of the stop bit of the final octet of a */
+/* received frame before a node may enable its EIA-485 driver: 40 bit times. */
+/* At 9600 baud, 40 bit times would be about 4.166 milliseconds */
+/* At 19200 baud, 40 bit times would be about 2.083 milliseconds */
+/* At 38400 baud, 40 bit times would be about 1.041 milliseconds */
+/* At 57600 baud, 40 bit times would be about 0.694 milliseconds */
+/* At 76800 baud, 40 bit times would be about 0.520 milliseconds */
+/* At 115200 baud, 40 bit times would be about 0.347 milliseconds */
+/* 40 bits is 4 octets including a start and stop bit with each octet */
+#define Tturnaround  (40UL)
+/* turnaround_time_milliseconds = (Tturnaround*1000UL)/RS485_Baud; */
+
 /****************************************************************************
 * DESCRIPTION: Initializes the RS485 hardware and variables, and starts in
 *              receive mode.
@@ -61,15 +74,13 @@ void RS485_Initialize(void)
     UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
     /* Clear Power Reduction USART0 */
     BIT_CLEAR(PRR,PRUSART0);
+    /* Use port PD2 for RTS - enable and disable of Transceiver Tx/Rx */
+    /* Set port bit as Output */
+    BIT_SET(DDRD,DDD2);
 
     return;
 }
 
-void RS485_Cleanup(void)
-{
-
-}
-
 /****************************************************************************
 * DESCRIPTION: Returns the baud rate that we are currently running at
 * RETURN:      none
@@ -83,7 +94,7 @@ uint32_t RS485_Get_Baud_Rate(void)
 
 /****************************************************************************
 * DESCRIPTION: Sets the baud rate for the chip USART
-* RETURN:      none
+* RETURN:      true if valid baud rate
 * ALGORITHM:   none
 * NOTES:       none
 *****************************************************************************/
@@ -113,23 +124,50 @@ bool RS485_Set_Baud_Rate(uint32_t baud)
     return valid;
 }
 
-/* Transmits a Frame on the wire */
+/****************************************************************************
-void RS485_Send_Frame(
+* DESCRIPTION: Waits on the SilenceTimer for 40 bits.
-    volatile struct mstp_port_struct_t *mstp_port, /* port specific data */
+* RETURN:      none
-    uint8_t * buffer,  /* frame to send (up to 501 bytes of data) */
+* ALGORITHM:   none
-    uint16_t nbytes)   /* number of bytes of data (up to 501) */
+* NOTES:       none
+*****************************************************************************/
+void RS485_Turnaround_Delay(void)
 {
-    uint8_t turnaround_time;
+    uint16_t turnaround_time;
+    
+    /* delay after reception before trasmitting - per MS/TP spec */
+    /* wait a minimum  40 bit times since reception */
+    /* at least 1 ms for errors: rounding, clock tick */
+    turnaround_time = 1 + ((Tturnaround*1000UL)/RS485_Baud);
+    while (Timer_Silence() < turnaround_time) {
+        /* do nothing - wait for timer to increment */
+    };
+}
 
-    /* delay after reception - per MS/TP spec */
+/****************************************************************************
-    if (mstp_port) {
+* DESCRIPTION: Enable or disable the transmitter
-        /* wait a minimum  40 bit times since reception */
+* RETURN:      none
-        /* at least 1 ms for errors: rounding, clock tick */
+* ALGORITHM:   none
-        turnaround_time = 1 + ((Tturnaround*1000UL)/RS485_Baud);
+* NOTES:       none
-        while (mstp_port->SilenceTimer() < turnaround_time) {
+*****************************************************************************/
-            /* do nothing - wait for timer to increment */
+void RS485_Transmitter_Enable(bool enable)
-        };
+{
+    if (enable) {
+        BIT_SET(PORTD,PD2);
+    } else {        
+        BIT_CLEAR(PORTD,PD2);
     }
+}
+
+/****************************************************************************
+* DESCRIPTION: Send some data and wait until it is sent
+* RETURN:      none
+* ALGORITHM:   none
+* NOTES:       none
+*****************************************************************************/
+void RS485_Send_Data(
+    uint8_t * buffer,       /* data to send */
+    uint8_t nbytes)       /* number of bytes of data */
+{
     while (nbytes) {
         while (!BIT_CHECK(UCSR0A,UDRE0)) {
             /* do nothing - wait until Tx buffer is empty */
@@ -142,34 +180,53 @@ void RS485_Send_Frame(
         /* do nothing - wait until the entire frame in the 
            Transmit Shift Register has been shifted out */
     }
-    /* per MSTP spec */
-    if (mstp_port) {
-        mstp_port->SilenceTimerReset();
-    }
-
-    return;
 }
 
-/* called by timer, interrupt(?) or other thread */
+
-void RS485_Check_UART_Data(struct mstp_port_struct_t *mstp_port)
+/****************************************************************************
+* DESCRIPTION: Return true if a framing or overrun error is present
+* RETURN:      true if error
+* ALGORITHM:   none
+* NOTES:       Clears any error flags.
+*****************************************************************************/
+bool RS485_ReceiveError(void)
 {
-    if (mstp_port->ReceiveError == true) {
+    bool uart_error = false;
-        /* wait for state machine to clear this */
+    uint8_t dummy_data;
-    }
-    /* wait for state machine to read from the DataRegister */
-    else if (mstp_port->DataAvailable == false) {
-        /* check for error */
-        if (BIT_CHECK(UCSR0A,FE0)) {
-            mstp_port->ReceiveError = true;
-        }
 
-        if (BIT_CHECK(UCSR0A,DOR0)) {
+    /* check for framing error */
-            mstp_port->ReceiveError = true;
+    if (BIT_CHECK(UCSR0A,FE0)) {
-        }
+        uart_error = true;
-        /* check for data */
+    }
-        if (BIT_CHECK(UCSR0A,RXC0)) {
+    /* check for overrun error */
-            mstp_port->DataRegister = UDR0;
+    if (BIT_CHECK(UCSR0A,DOR0)) {
-            mstp_port->DataAvailable = true;
+        uart_error = true;
+    }
+    /* flush the receive buffer */
+    if (uart_error) {
+        while (BIT_CHECK(UCSR0A,RXC0)) {
+            dummy_data = UDR0;
         }
     }
+    
+    return uart_error;
+}
+
+/****************************************************************************
+* DESCRIPTION: Return true if data is available 
+* RETURN:      true if data is available, with the data in the parameter set
+* ALGORITHM:   none
+* NOTES:       none
+*****************************************************************************/
+bool RS485_DataAvailable(uint8_t *data)
+{
+    bool uart_data = false;
+    
+    /* check for data */
+    if (BIT_CHECK(UCSR0A,RXC0)) {
+        *data = UDR0;
+        uart_data = true;
+    }
+    
+    return uart_data;
 }

bacnet-stack/ports/atmega168/rs485.h

@@ -1,33 +1,42 @@
-/**************************************************************************
+/*####COPYRIGHTBEGIN####
-*
+ -------------------------------------------
-* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
+ Copyright (C) 2004 Steve Karg
-*
+
-* Permission is hereby granted, free of charge, to any person obtaining
+ This program is free software; you can redistribute it and/or
-* a copy of this software and associated documentation files (the
+ modify it under the terms of the GNU General Public License
-* "Software"), to deal in the Software without restriction, including
+ as published by the Free Software Foundation; either version 2
-* without limitation the rights to use, copy, modify, merge, publish,
+ of the License, or (at your option) any later version.
-* distribute, sublicense, and/or sell copies of the Software, and to
+
-* permit persons to whom the Software is furnished to do so, subject to
+ This program is distributed in the hope that it will be useful,
-* the following conditions:
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
-*
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-* The above copyright notice and this permission notice shall be included
+ GNU General Public License for more details.
-* in all copies or substantial portions of the Software.
+
-*
+ You should have received a copy of the GNU General Public License
-* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ along with this program; if not, write to:
-* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ The Free Software Foundation, Inc.
-* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ 59 Temple Place - Suite 330
-* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ Boston, MA  02111-1307
-* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ USA.
-* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+
-* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ As a special exception, if other files instantiate templates or
-*
+ use macros or inline functions from this file, or you compile
-*********************************************************************/
+ this file and link it with other works to produce a work based
+ on this file, this file does not by itself cause the resulting
+ work to be covered by the GNU General Public License. However
+ the source code for this file must still be made available in
+ accordance with section (3) of the GNU General Public License.
+
+ This exception does not invalidate any other reasons why a work
+ based on this file might be covered by the GNU General Public
+ License.
+ -------------------------------------------
+####COPYRIGHTEND####*/
 
 #ifndef RS485_H
 #define RS485_H
 
 #include <stdint.h>
-#include "mstp.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -35,14 +44,17 @@ extern "C" {
 
     void RS485_Initialize(void);
 
-    void RS485_Send_Frame(
+    void RS485_Transmitter_Enable(bool enable);
-        volatile struct mstp_port_struct_t *mstp_port, /* port specific data */
-        uint8_t * buffer,  /* frame to send (up to 501 bytes of data) */
-        uint16_t nbytes);  /* number of bytes of data (up to 501) */
 
-    uint8_t RS485_Check_UART_Data(
+    /* NOTE: Only able to send up to 255 bytes at a time */
-        volatile struct mstp_port_struct_t *mstp_port); /* port specific data */
+    void RS485_Send_Data(
+        uint8_t * buffer,       /* data to send */
+        uint8_t nbytes);       /* number of bytes of data */
 
+    bool RS485_ReceiveError(void);
+    bool RS485_DataAvailable(uint8_t *data);
+
+    void RS485_Turnaround_Delay(void);
     uint32_t RS485_Get_Baud_Rate(void);
     bool RS485_Set_Baud_Rate(uint32_t baud);