diff --git a/bacnet-stack/include/rp.h b/bacnet-stack/include/rp.h
index ea9f006b..2c583291 100644
--- a/bacnet-stack/include/rp.h
+++ b/bacnet-stack/include/rp.h
@@ -62,6 +62,16 @@ extern "C" {
         unsigned apdu_len,
         BACNET_READ_PROPERTY_DATA * rpdata);
 
+    /* method to encode the ack without extra buffer */
+    int rp_ack_encode_apdu_init(
+        uint8_t * apdu,
+        uint8_t invoke_id,
+        BACNET_READ_PROPERTY_DATA * rpdata);
+
+    int rp_ack_encode_apdu_object_property_end(
+        uint8_t * apdu);
+    
+    /* method to encode the ack using extra buffer */
     int rp_ack_encode_apdu(
         uint8_t * apdu,
         uint8_t invoke_id,
diff --git a/bacnet-stack/ports/atmega168/h_rp.c b/bacnet-stack/ports/atmega168/h_rp.c
index e9dc533c..d9910b1b 100644
--- a/bacnet-stack/ports/atmega168/h_rp.c
+++ b/bacnet-stack/ports/atmega168/h_rp.c
@@ -45,8 +45,6 @@
 #include "bv.h"
 #endif
 
-static uint8_t Temp_Buf[MAX_APDU] = { 0 };
-
 /* Encodes the property APDU and returns the length,
    or sets the error, and returns -1 */
 int Encode_Property_APDU(
@@ -97,6 +95,7 @@ void handler_read_property(
 {
     BACNET_READ_PROPERTY_DATA data;
     int len = 0;
+    int ack_len = 0;
     int pdu_len = 0;
     BACNET_NPDU_DATA npdu_data;
     bool error = false;
@@ -126,18 +125,19 @@ void handler_read_property(
     } else {
         /* most cases will be error */
         error = true;
-        len =
-            Encode_Property_APDU(&Temp_Buf[0], data.object_type,
+        ack_len = rp_ack_encode_apdu_init(
+            &Handler_Transmit_Buffer[pdu_len],
+            service_data->invoke_id, &data);
+        /* FIXME: add buffer len as passed into function or use smart buffer */
+        len = Encode_Property_APDU(
+            &Handler_Transmit_Buffer[pdu_len + ack_len], data.object_type,
             data.object_instance, data.object_property, data.array_index,
             &error_class, &error_code);
         if (len >= 0) {
-            /* encode the APDU portion of the packet */
-            data.application_data = &Temp_Buf[0];
-            data.application_data_len = len;
-            /* FIXME: probably need a length limitation sent with encode */
-            len =
-                rp_ack_encode_apdu(&Handler_Transmit_Buffer[pdu_len],
-                service_data->invoke_id, &data);
+            pdu_len = pdu_len + len + ack_len;
+            len = rp_ack_encode_apdu_object_property_end(
+                &Handler_Transmit_Buffer[pdu_len]);
+            pdu_len += len;
             error = false;
         }
     }
diff --git a/bacnet-stack/src/rp.c b/bacnet-stack/src/rp.c
index 8e0a8ce9..6aa36ecf 100644
--- a/bacnet-stack/src/rp.c
+++ b/bacnet-stack/src/rp.c
@@ -118,6 +118,52 @@ int rp_decode_service_request(
     return (int) len;
 }
 
+/* alternate method to encode the ack without extra buffer */
+int rp_ack_encode_apdu_init(
+    uint8_t * apdu,
+    uint8_t invoke_id,
+    BACNET_READ_PROPERTY_DATA * rpdata)
+{
+    int len = 0;        /* length of each encoding */
+    int apdu_len = 0;   /* total length of the apdu, return value */
+
+    if (apdu) {
+        apdu[0] = PDU_TYPE_COMPLEX_ACK; /* complex ACK service */
+        apdu[1] = invoke_id;    /* original invoke id from request */
+        apdu[2] = SERVICE_CONFIRMED_READ_PROPERTY;      /* service choice */
+        apdu_len = 3;
+        /* service ack follows */
+        apdu_len +=
+            encode_context_object_id(&apdu[apdu_len], 0, 
+            rpdata->object_type, rpdata->object_instance);
+        apdu_len +=
+            encode_context_enumerated(&apdu[apdu_len], 1,
+            rpdata->object_property);
+        /* context 2 array index is optional */
+        if (rpdata->array_index != BACNET_ARRAY_ALL) {
+            apdu_len +=
+                encode_context_unsigned(&apdu[apdu_len], 2,
+                rpdata->array_index);
+        }
+        apdu_len += encode_opening_tag(&apdu[apdu_len], 3);
+    }
+
+    return apdu_len;
+}
+
+/* note: encode the application tagged data yourself */
+int rp_ack_encode_apdu_object_property_end(
+    uint8_t * apdu)
+{
+    int apdu_len = 0;   /* total length of the apdu, return value */
+
+    if (apdu) {
+        apdu_len = encode_closing_tag(&apdu[0], 3);
+    }
+
+    return apdu_len;
+}
+
 int rp_ack_encode_apdu(
     uint8_t * apdu,
     uint8_t invoke_id,