diff --git a/avr/com.asm b/avr/com.asm
index 7d913fb..0ef2fd9 100644
--- a/avr/com.asm
+++ b/avr/com.asm
@@ -43,6 +43,10 @@
 .equ COM_CMD_I2CBUSMEMBER         = 4
 .equ COM_CMD_DEBUG                = 5
 
+.equ COM_ERR_NOTFORME             = 1
+.equ COM_ERR_CHECKSUM             = 2
+.equ COM_ERR_IO                   = 3
+
 
 ; ***************************************************************************
 ; data
@@ -89,21 +93,25 @@ comIsrPcint0:
     push r1
       push r16
         push r17
-          push r20
-            push r21
-              push r22
-                push xh
-                 push xl
-                   push yh
-                     push yl
-                       rcall comReceivePacketHandleBuffer ; (R1, R16, R17, R20, R21, R22, X, Y)
-                     pop yl
-                   pop yh
-                 pop xl
-                pop xh
-              pop r22
-            pop r21
-          pop r20
+          push r18
+            push r19
+              push r20
+                push r21
+                  push r22
+                    push xh
+                     push xl
+                       push yh
+                         push yl
+                           rcall comReceivePacketHandleBuffer ; (R1, R16, R17, R18, R19, R20, R21, R22, X, Y
+                         pop yl
+                       pop yh
+                     pop xl
+                    pop xh
+                  pop r22
+                pop r21
+              pop r20
+            pop r19
+          pop r18
         pop r17
       pop r16
     pop r1
@@ -130,7 +138,7 @@ Com_Init:
   ldi r17, (comDataEnd-comDataBegin)
   rcall Utils_FillSram
 
-  ldi r16, 2          ; debug: set fixed address "2"
+  ldi r16, 1          ; debug: set fixed address "1"
   sts comAddress, r16
 
   ; setup pins and interrupts
@@ -732,7 +740,7 @@ comSendPacketFromSram_error:
 ; - nothing
 ; OUT:
 ; - CFLAG: set if okay, cleared otherwise
-; MODIFIED REGISTERS: R16, R17, X, Y (R1, R20, R21, R22)
+; MODIFIED REGISTERS: R16, R17, X, Y (R1, R18, R19, R20, R21, R22)
 
 comReceivePacketHandleBuffer:
   rcall COM_BufferAlloc
@@ -744,20 +752,32 @@ comReceivePacketHandleBuffer:
   clr r17
   add xl, r16
   adc xh, r17
-  rcall comReceivePacketToSram        ; (r1, r16, r17, R20, R21, R22, X)
+  rcall comReceivePacketToSram               ; (r1, r16, r17, R20, R21, R22, X)
   brcc comReceivePacketHandleBuffer_dealloc
   ; handle buffer flags
   ldi r16, COM_BUFFER_FLAGS_RECEIVED
   std y+COM_BUFFER_OFFS_FLAGS, r16
+  ldi xl, LOW(comStatsPacketsIn)
+  ldi xh, HIGH(comStatsPacketsIn)
+  rcall Utils_IncrementCounter16              ; (r18, r19, 22)
   sec
   ret
 
 comReceivePacketHandleBuffer_dealloc:
-  rcall COM_BufferDeallocBack                ; (r16, r17, r21)
+  push r16
+    rcall COM_BufferDeallocBack                 ; (r16, r17, r21)
+  pop r16
+  cpi r16, COM_ERR_NOTFORME                     ; packet just not for me?
+  breq comReceivePacketHandleBuffer_notforme    ; correct, don't count as error
+  ldi xl, LOW(comStatsRecvErrs)
+  ldi xh, HIGH(comStatsRecvErrs)
+  rcall Utils_IncrementCounter16                ; (r18, r19, 22)
 comReceivePacketHandleBuffer_error:
   clc
   ret
-
+comReceivePacketHandleBuffer_notforme:          ; TODO: may count packets not for me?
+  clc
+  ret
 
 
 ; ---------------------------------------------------------------------------
@@ -782,6 +802,7 @@ comReceivePacketToSram:
   lds r17, comAddress
   cp r16, r17
   breq comReceivePacketToSram_acceptAddr
+  ldi r16, COM_ERR_NOTFORME
   clc                                          ; not for me
   ret
 comReceivePacketToSram_acceptAddr:
@@ -813,8 +834,13 @@ comReceivePacketToSram_readXOR:
   brne comReceivePacketToSram_error
   sec
   ret
+comReceivePacketToSram_crcError:
+  ldi r16, COM_ERR_CHECKSUM
+  clc
+  ret
 
 comReceivePacketToSram_error:
+  ldi r16, COM_ERR_IO
   clc
   ret