Tuned the ATmega168 port demo project that runs a Device Object and 9 Analog Inputs, and uses ReadProperty service. Uses 16158 bytes of flash, 624 bytes of RAM with an APDU of 128.

bacnet-stack/ports/atmega168/Makefile

@@ -91,7 +91,7 @@ OPTIMIZATION = -Os -mcall-prologues
 
 ## Compile options common for all C compilation units.
 BFLAGS = -DBACDL_MSTP
-BFLAGS += -DMAX_APDU=50
+BFLAGS += -DMAX_APDU=128
 BFLAGS += -DBIG_ENDIAN=0
 BFLAGS += -DMAX_TSM_TRANSACTIONS=0
 #BFLAGS += -DCRC_USE_TABLE

bacnet-stack/ports/atmega168/ai.c

@@ -34,12 +34,12 @@
 #include "config.h"
 
 /* Analog Input = Photocell */
-#define MAX_ANALOG_INPUTS 2
+#define MAX_ANALOG_INPUTS 9
 #if (MAX_ANALOG_INPUTS > 9)
     #error Modify the Analog_Input_Name to handle multiple digits 
 #endif
 
-static uint8_t Present_Value[MAX_ANALOG_INPUTS];
+static float Present_Value[MAX_ANALOG_INPUTS];
 
 /* we simply have 0-n object instances.  Yours might be */
 /* more complex, and then you need validate that the */
@@ -76,16 +76,6 @@ char *Analog_Input_Name(uint32_t object_instance)
     return NULL;
 }
 
-static float Analog_Input_Present_Value(uint32_t object_instance)
-{
-  float value = 0.0;
-  
-  if (object_instance < MAX_ANALOG_INPUTS)
-    value = Present_Value[object_instance];
-    
-  return value;
-}
-
 /* return apdu length, or -1 on error */
 /* assumption - object has already exists */
 int Analog_Input_Encode_Property_APDU(uint8_t * apdu,
@@ -105,7 +95,8 @@ int Analog_Input_Encode_Property_APDU(uint8_t * apdu,
             object_instance);
         break;
     /* note: Name and Description don't have to be the same.
-       You could make Description writable and different */
+       You could make Description writable and different.
+       Note that Object-Name must be unique in this device */
     case PROP_OBJECT_NAME:
     case PROP_DESCRIPTION:
         characterstring_init_ansi(&char_string,
@@ -118,7 +109,7 @@ int Analog_Input_Encode_Property_APDU(uint8_t * apdu,
         break;
     case PROP_PRESENT_VALUE:
         apdu_len = encode_application_real(&apdu[0], 
-            Analog_Input_Present_Value(object_instance));
+            Present_Value[object_instance]);
         break;
     case PROP_STATUS_FLAGS:
         bitstring_init(&bit_string);

bacnet-stack/ports/atmega168/device.c

@@ -49,8 +49,8 @@
    properties that are writable or that may change.
    The properties that are constant can be hard coded
    into the read-property encoding. */
-static uint32_t Object_Instance_Number = 12345;
+static uint32_t Object_Instance_Number = 260001;
-static char Object_Name[32] = "ATmega Device";
+static char Object_Name[32] = "ATmega168 Device";
 static BACNET_DEVICE_STATUS System_Status = STATUS_OPERATIONAL;
 
 void Device_Init(void)
@@ -203,8 +203,6 @@ int Device_Encode_Property_APDU(uint8_t * apdu,
     int object_type = 0;
     uint32_t instance = 0;
     unsigned count = 0;
-    BACNET_TIME local_time;
-    BACNET_DATE local_date;
 
     /* FIXME: change the hardcoded names to suit your application */
     switch (property) {
@@ -213,16 +211,13 @@ int Device_Encode_Property_APDU(uint8_t * apdu,
             Object_Instance_Number);
         break;
     case PROP_OBJECT_NAME:
+    case PROP_DESCRIPTION:
         characterstring_init_ansi(&char_string, Object_Name);
         apdu_len = encode_application_character_string(&apdu[0], &char_string);
         break;
     case PROP_OBJECT_TYPE:
         apdu_len = encode_application_enumerated(&apdu[0], OBJECT_DEVICE);
         break;
-    case PROP_DESCRIPTION:
-        characterstring_init_ansi(&char_string, "BACnet Demo");
-        apdu_len = encode_application_character_string(&apdu[0], &char_string);
-        break;
     case PROP_SYSTEM_STATUS:
         apdu_len =
             encode_application_enumerated(&apdu[0], System_Status);
@@ -247,21 +242,11 @@ int Device_Encode_Property_APDU(uint8_t * apdu,
         characterstring_init_ansi(&char_string, "1.0");
         apdu_len = encode_application_character_string(&apdu[0], &char_string);
         break;
-    case PROP_LOCATION:
-        characterstring_init_ansi(&char_string, "USA");
-        apdu_len = encode_application_character_string(&apdu[0], &char_string);
-        break;
     case PROP_PROTOCOL_VERSION:
-        apdu_len =
+        apdu_len = encode_application_unsigned(&apdu[0], 1);
-            encode_application_unsigned(&apdu[0], 1);
         break;
     case PROP_PROTOCOL_REVISION:
-        apdu_len =
+        apdu_len = encode_application_unsigned(&apdu[0], 5);
-            encode_application_unsigned(&apdu[0], 5);
-        break;
-        /* BACnet Legacy Support */
-    case PROP_PROTOCOL_CONFORMANCE_CLASS:
-        apdu_len = encode_application_unsigned(&apdu[0], 1);
         break;
     case PROP_PROTOCOL_SERVICES_SUPPORTED:
         /* Note: list of services that are executed, not initiated. */
@@ -277,11 +262,6 @@ int Device_Encode_Property_APDU(uint8_t * apdu,
         /* Note: this is the list of objects that can be in this device,
            not a list of objects that this device can access */
         bitstring_init(&bit_string);
-        for (i = 0; i < MAX_ASHRAE_OBJECT_TYPE; i++) {
-            /* FIXME: if ReadProperty used an array of Functions... */
-            /* initialize all the object types to not-supported */
-            bitstring_set_bit(&bit_string, (uint8_t) i, false);
-        }
         /* FIXME: indicate the objects that YOU support */
         bitstring_set_bit(&bit_string, OBJECT_DEVICE, true);
         bitstring_set_bit(&bit_string, OBJECT_ANALOG_INPUT, true);
@@ -367,30 +347,6 @@ int Device_Encode_Property_APDU(uint8_t * apdu,
     case PROP_MAX_MASTER:
         apdu_len = encode_application_unsigned(&apdu[0], dlmstp_max_master());
         break;
-    case PROP_LOCAL_TIME:
-        /* FIXME: if you support time */
-        local_time.hour = 0;
-        local_time.min = 0;
-        local_time.sec = 0;
-        local_time.hundredths = 0;
-        apdu_len = encode_application_time(&apdu[0], &local_time);
-        break;
-    case PROP_UTC_OFFSET:
-        /* Note: BACnet Time Zone is inverse of everybody else */
-        apdu_len = encode_application_signed(&apdu[0], 5 /* EST */ );
-        break;
-    case PROP_LOCAL_DATE:
-        /* FIXME: if you support date */
-        local_date.year = 2006; /* AD */
-        local_date.month = 4;   /* Jan=1..Dec=12 */
-        local_date.day = 11;    /* 1..31 */
-        local_date.wday = 0;    /* 1=Mon..7=Sun */
-        apdu_len = encode_application_date(&apdu[0], &local_date);
-        break;
-    case PROP_DAYLIGHT_SAVINGS_STATUS:
-        /* FIXME: if you support time/date */
-        apdu_len = encode_application_boolean(&apdu[0], false);
-        break;
     case 9600:
         apdu_len = encode_application_unsigned(&apdu[0], RS485_Get_Baud_Rate());
         break;
@@ -519,4 +475,4 @@ bool Device_Write_Property(BACNET_WRITE_PROPERTY_DATA * wp_data,
 
     return status;
 }
-#endif
+#endif

bacnet-stack/ports/atmega168/dlmstp.c

@@ -402,7 +402,8 @@ static void MSTP_Send_Frame(
 {                               /* number of bytes of data (up to 501) */
     uint8_t crc8 = 0xFF;        /* used to calculate the crc value */
     uint16_t crc16 = 0xFFFF;    /* used to calculate the crc value */
-    uint8_t buffer[8]; /* stores the header and data crc */
+    uint8_t buffer[8]; /* stores the header and crc */
+    uint8_t datacrc[2]; /* stores the data crc */
     uint16_t i = 0;         /* used to calculate CRC for data */
 
     /* create the MS/TP header */
@@ -419,10 +420,6 @@ static void MSTP_Send_Frame(
     buffer[6] = data_len % 256;
     crc8 = CRC_Calc_Header(buffer[6], crc8);
     buffer[7] = ~crc8;
-    RS485_Turnaround_Delay();
-    RS485_Transmitter_Enable(true);
-    RS485_Send_Data(buffer,8);
-    /* send any data */
     if (data_len) {
         /* calculate CRC for any data */
         for (i = 0; i < data_len; i++)
@@ -430,10 +427,17 @@ static void MSTP_Send_Frame(
             crc16 = CRC_Calc_Data(data[i], crc16);
         }
         crc16 = ~crc16;
-        buffer[0] = (crc16 & 0x00FF);
+        datacrc[0] = (crc16 & 0x00FF);
-        buffer[1] = ((crc16 & 0xFF00) >> 8);
+        datacrc[1] = ((crc16 & 0xFF00) >> 8);
+    }
+    /* now transmit the frame */
+    RS485_Turnaround_Delay();
+    RS485_Transmitter_Enable(true);
+    RS485_Send_Data(buffer,8);
+    /* send any data */
+    if (data_len) {
         RS485_Send_Data(data, data_len);
-        RS485_Send_Data(buffer, 2);
+        RS485_Send_Data(datacrc, 2);
     }
     RS485_Transmitter_Enable(false);
 }

bacnet-stack/ports/atmega168/h_whois.c

@@ -45,16 +45,18 @@ void handler_who_is(uint8_t * service_request,
     int len = 0;
     int32_t low_limit = 0;
     int32_t high_limit = 0;
+    int32_t target_device;
 
     (void) src;
     len = whois_decode_service_request(service_request,
         service_len, &low_limit, &high_limit);
-    if (len == 0)
+    if (len == 0) {
-        iam_send(&Handler_Transmit_Buffer[0]);
+        Send_I_Am = true;
-    else if (len != -1) {
+    } else if (len != -1) {
         /* is my device id within the limits? */
-        if (((Device_Object_Instance_Number() >= (uint32_t) low_limit) &&
+        target_device = Device_Object_Instance_Number();
-                (Device_Object_Instance_Number() <= (uint32_t) high_limit))
+        if (((target_device >= low_limit) &&
+                (target_device <=  high_limit))
             ||
             /* BACnet wildcard is the max instance number - everyone responds */
             ((BACNET_MAX_INSTANCE >= (uint32_t) low_limit) &&

bacnet-stack/ports/atmega168/main.c

@@ -152,23 +152,23 @@ 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
     datalink_init(NULL);
     for (;;) {
-        if (Send_I_Am)
+        if (Send_I_Am) {
+                Send_I_Am = false;
                 iam_send(&Handler_Transmit_Buffer[0]);
+        }
         input_switch_read();
         task_milliseconds();
         /* other tasks */
         /* BACnet handling */
         pdu_len = datalink_receive(&src, &PDUBuffer[0], sizeof(PDUBuffer), 0);
         if (pdu_len) {
-#if !defined(TEST_MSTP)
             npdu_handler(&src, &PDUBuffer[0], pdu_len);
-#endif
             NPDU_LED_On();
         }
     }