bacnet-stack/ports/atmega168/dlmstp.c

@@ -185,13 +185,13 @@ static uint8_t TransmitPacketDest;
 /* that a node must wait for a station to begin replying to a */
 /* confirmed request: 255 milliseconds. (Implementations may use */
 /* larger values for this timeout, not to exceed 300 milliseconds.) */
-#define Treply_timeout 260
+#define Treply_timeout 295
 
 /* The minimum time without a DataAvailable or ReceiveError event that a */
 /* node must wait for a remote node to begin using a token or replying to */
 /* a Poll For Master frame: 20 milliseconds. (Implementations may use */
 /* larger values for this timeout, not to exceed 100 milliseconds.) */
-#define Tusage_timeout 25
+#define Tusage_timeout 95
 
 /* The number of tokens received or used before a Poll For Master cycle */
 /* is executed: 50. */

bacnet-stack/ports/atmega168/main.c

@@ -80,7 +80,6 @@ void init(void)
 
     /* Configure USART */
     RS485_Initialize();
-    RS485_Set_Baud_Rate(38400);
 
     /* Configure Timer0 for millisecond timer */
     Timer_Initialize();
@@ -163,7 +162,7 @@ int main(void)
     
     init();
 #if defined(BACDL_MSTP)
-    RS485_Set_Baud_Rate(38400);
+    //RS485_Set_Baud_Rate(38400);
     dlmstp_set_max_master(127);
     dlmstp_set_max_info_frames(1);
 #endif

bacnet-stack/ports/atmega168/rs485.c

@@ -31,7 +31,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include "mstp.h"
+//#include "mstp.h"
 
 /* This file has been customized for use with ATMEGA168 */
 #include "hardware.h"
@@ -42,7 +42,19 @@ static uint8_t LED1_Off_Timer;
 static uint8_t LED3_Off_Timer;
 
 /* baud rate */
-static uint32_t RS485_Baud = 38400;
+static uint32_t RS485_Baud = 9600;
+/* autobaud - switch baud on errors if autobaud is true */
+static bool RS485_Autobaud = true;
+/* we saw some data, so we are on an active wire */
+static uint8_t RS485_Data_Count;
+/* count of errors before autobaud switching */
+static uint8_t RS485_Error_Count;
+/* time limit */
+#define RS485_ERROR_TIMEOUT 1000
+/* millisecond timer to limit error window */
+static uint16_t RS485_Error_Timer = RS485_ERROR_TIMEOUT;
+/* number of errors in 1000ms before autobaud switching */
+#define RS485_ERROR_LIMIT 30
 
 /* 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. */
@@ -141,6 +153,34 @@ bool RS485_Set_Baud_Rate(uint32_t baud)
     return valid;
 }
 
+void RS485_Next_Baud_Rate(void)
+{
+    uint32_t baud;
+
+    switch (RS485_Baud) {
+        case 9600:
+            baud = 19200;
+            break;
+        case 19200:
+            baud = 38400;
+            break;
+        case 38400:
+            baud = 57600;
+            break;
+        case 57600:
+            baud = 76800;
+            break;
+        case 76800:
+            baud = 115200;
+            break;
+        case 115200:
+        default:
+            baud = 9600;
+            break;
+    }
+    RS485_Set_Baud_Rate(baud);
+}
+
 /****************************************************************************
 * DESCRIPTION: Waits on the SilenceTimer for 40 bits.
 * RETURN:      none
@@ -201,6 +241,9 @@ void RS485_LED_Timers(void)
             BIT_SET(PORTD,PD7);
         }
     }
+    if (RS485_Error_Timer) {
+        RS485_Error_Timer--;
+    }
 }
 
 /****************************************************************************
@@ -263,7 +306,7 @@ void RS485_Send_Data(
 /****************************************************************************
 * DESCRIPTION: Return true if a framing or overrun error is present
 * RETURN:      true if error
-* ALGORITHM:   none
+* ALGORITHM:   autobaud - if there are a lot of errors, switch baud rate
 * NOTES:       Clears any error flags.
 *****************************************************************************/
 bool RS485_ReceiveError(void)
@@ -285,6 +328,34 @@ bool RS485_ReceiveError(void)
         do {
             dummy_data = UDR0;
         } while (BIT_CHECK(UCSR0A,RXC0));
+        /* count errors during autobaud */
+        if (RS485_Error_Count < RS485_ERROR_LIMIT) {
+            RS485_Error_Count++;
+        } else {
+            if (RS485_Autobaud && RS485_Error_Timer) {
+                /* We are in autobaud mode, and there were excessive 
+                   errors while the timer was counting down */
+                RS485_Next_Baud_Rate();
+                RS485_Error_Timer = RS485_ERROR_TIMEOUT;
+                RS485_Error_Count = 0;
+            } else if (RS485_Autobaud) {
+                /* autobaud, but timer expired */
+                RS485_Autobaud = false;
+            }
+        }
+    } else {
+       if (RS485_Autobaud) {
+           if ((RS485_Error_Timer == 0) && (RS485_Error_Count == 0)) {
+               if (RS485_Data_Count > 8) {
+                   /* no errors, timer expired, and we saw data */
+                   RS485_Autobaud = false;
+               } else {
+                   /* no errors, timer expired, and no data*/
+                   RS485_Error_Timer = RS485_ERROR_TIMEOUT;
+               }
+           }
+       }
+
     }
     
     return ReceiveError;
@@ -305,6 +376,8 @@ bool RS485_DataAvailable(uint8_t *data)
         *data = UDR0;
         DataAvailable = true;
         RS485_LED1_On();
+        if (RS485_Data_Count < 0xFF)
+            RS485_Data_Count++;
     }
 
     return DataAvailable;