From 81b008af0c87340d8eb8bd25729f40529cc202fa Mon Sep 17 00:00:00 2001
From: Martin Preuss <martin@aquamaniac.de>
Date: Sun, 6 Jul 2025 17:19:59 +0200
Subject: [PATCH] r05, comOnUart0 and comOnUart1 work!

---
 avr/devices/r05/main/main.asm       |  21 +-
 avr/devices/r05/test/main.asm       |  35 ++-
 avr/modules/uart_hw2/comonuart0.asm | 390 +++++++++------------------
 avr/modules/uart_hw2/comonuart1.asm | 404 +++++++++-------------------
 avr/modules/uart_hw2/defs.asm       |  18 +-
 5 files changed, 302 insertions(+), 566 deletions(-)

diff --git a/avr/devices/r05/main/main.asm b/avr/devices/r05/main/main.asm
index 14ccb80..dc6d041 100644
--- a/avr/devices/r05/main/main.asm
+++ b/avr/devices/r05/main/main.asm
@@ -129,12 +129,12 @@
         reti                          ; 21: SPI               SPI Serial Transfer Complete
         reti                          ; 22: USART0_RXS        USART0 Rx Start
         rjmp ComOnUart0_RxCharIsr     ; 23: USART0_RXC        USART0 Rx Complete
-        rjmp ComOnUart0_TxUdreIsr     ; 24: USART0_DRE        USART0 Data Register Empty
-        rjmp ComOnUart0_TxCharIsr     ; 25: USART0_TXC        USART0 Tx Complete
+        reti                          ; 24: USART0_DRE        USART0 Data Register Empty
+        reti                          ; 25: USART0_TXC        USART0 Tx Complete
         reti                          ; 26: USART1_RXS        USART1 Rx Start
         rjmp ComOnUart1_RxCharIsr     ; 27: USART1_RXC        USART1 Rx Complete
-        rjmp ComOnUart1_TxUdreIsr     ; 28: USART1_DRE        USART1 Data Register Empty
-        rjmp ComOnUart1_TxCharIsr     ; 29: USART1_TXC        USART1 Tx Complete
+        reti                          ; 28: USART1_DRE        USART1 Data Register Empty
+        reti                          ; 29: USART1_TXC        USART1 Tx Complete
         reti                          ; 30: TWI               Two-Wire-Interface
         reti                          ; 31: RESERVED          reserved
 
@@ -162,6 +162,13 @@ firmwareStart:
 ; @routine onSystemStart
 
 onSystemStart:
+  ; set interface number for UART0
+  ldi r16, COMONUART0_IFACENUM
+  sts comOnUart0_iface+NET_IFACE_OFFS_IFACENUM, r16
+  ; set interface number for UART1
+  ldi r16, COMONUART1_IFACENUM
+  sts comOnUart1_iface+NET_IFACE_OFFS_IFACENUM, r16
+
   ret
 ; @end
 
@@ -230,7 +237,7 @@ checkRecvdMsg:
 
     ; forward to other interface
     ld r17, X
-    andi r17, (NET_IFACE_BUFFER_IFACENUM1_BIT | NET_IFACE_BUFFER_IFACENUM0_BIT)
+    andi r17, (1<<NET_IFACE_BUFFER_IFACENUM1_BIT) | (1<<NET_IFACE_BUFFER_IFACENUM0_BIT)
     rcall reverseInterfaceNum                 ; (R16, R17)
 ;    ldi r17, COMONUART0_IFACENUM ; DEBUG: send everything to uart0 to test that code first
     rcall addMsgToInterface
@@ -288,6 +295,7 @@ letSysHandleMsg_end:
 reverseInterfaceNum:
   ldi r16, (1<<NET_IFACE_BUFFER_IFACENUM1_BIT) | (1<<NET_IFACE_BUFFER_IFACENUM0_BIT)
   eor r17, r16
+  and r17, r16
   ret
 ; @end
 
@@ -319,6 +327,9 @@ addMsgToInterface_end:
 sendPacketsIface2In:
   ldi yl, LOW(netInterfaceData)
   ldi yh, HIGH(netInterfaceData)
+;  ldi yl, LOW(comOnUart1_iface)
+;  ldi yh, HIGH(comOnUart1_iface)
+
   ldi r17, AQHOME_VALUEID_STATS_PACKETS_IN2
   lds r18, comOnUart1_iface+NET_IFACE_OFFS_PACKETSIN_LOW
   lds r19, comOnUart1_iface+NET_IFACE_OFFS_PACKETSIN_HIGH
diff --git a/avr/devices/r05/test/main.asm b/avr/devices/r05/test/main.asm
index 4874b8c..fe106ee 100644
--- a/avr/devices/r05/test/main.asm
+++ b/avr/devices/r05/test/main.asm
@@ -75,8 +75,8 @@
 ;#define MODULES_MOTION
 #define MODULES_NETWORK
 ;#define MODULES_TTYONUART1
-;#define MODULES_COMONUART0
-#define MODULES_COMONUART1
+#define MODULES_COMONUART0
+;#define MODULES_COMONUART1
 
 #define APPS_STATS
 #define APPS_NETWORK
@@ -113,9 +113,10 @@
 
         rjmp BOOTLOADER_ADDR          ;  1: RESET             Reset vector  use this for flashed system
 	reti                          ;  2: INT0              External Interrupt Request 0
-;        rjmp ComOnUart0_AttnChangeIsr ;  3: PCINT0            Pin Change Interrupt 0
-	reti                          ;  3: PCINT0            Pin Change Interrupt 0
-	rjmp ComOnUart1_AttnChangeIsr ;  4: PCINT1            Pin Change Interrupt 1
+        rjmp ComOnUart0_AttnChangeIsr ;  3: PCINT0            Pin Change Interrupt 0
+;	reti                          ;  3: PCINT0            Pin Change Interrupt 0
+;	rjmp ComOnUart1_AttnChangeIsr ;  4: PCINT1            Pin Change Interrupt 1
+	reti                          ;  4: PCINT1            Pin Change Interrupt 1
 	reti                          ;  5: WDT               Watchdog Time-out
 	reti                          ;  6: TIM1_CAPT         Timer/Counter1 Capture Event
 	reti                          ;  7: TIM1_COMPA (OC1A) Timer/Counter1 Compare Match A
@@ -134,19 +135,17 @@
         reti                          ; 20: TIM2_OVF (OVF2)   Timer/Counter2 Overflow
         reti                          ; 21: SPI               SPI Serial Transfer Complete
         reti                          ; 22: USART0_RXS        USART0 Rx Start
-;        rjmp ComOnUart0_RxCharIsr     ; 23: USART0_RXC        USART0 Rx Complete
-        reti                          ; 23: USART0_RXC        USART0 Rx Complete
+        rjmp ComOnUart0_RxCharIsr     ; 23: USART0_RXC        USART0 Rx Complete
+;        reti                          ; 23: USART0_RXC        USART0 Rx Complete
 ;        rjmp ComOnUart0_TxUdreIsr     ; 24: USART0_DRE        USART0 Data Register Empty
         reti                          ; 24: USART0_DRE        USART0 Data Register Empty
 ;        rjmp ComOnUart0_TxCharIsr     ; 25: USART0_TXC        USART0 Tx Complete
         reti                          ; 25: USART0_TXC        USART0 Tx Complete
         reti                          ; 26: USART1_RXS        USART1 Rx Start
-        rjmp ComOnUart1_RxCharIsr     ; 27: USART1_RXC        USART1 Rx Complete
-;        reti                          ; 27: USART1_RXC        USART1 Rx Complete
-        rjmp ComOnUart1_TxUdreIsr     ; 28: USART1_DRE        USART1 Data Register Empty
-;        reti                          ; 28: USART1_DRE        USART1 Data Register Empty
-        rjmp ComOnUart1_TxCharIsr     ; 29: USART1_TXC        USART1 Tx Complete
-;        reti                          ; 29: USART1_TXC        USART1 Tx Complete
+;        rjmp ComOnUart1_RxCharIsr     ; 27: USART1_RXC        USART1 Rx Complete
+        reti                          ; 27: USART1_RXC        USART1 Rx Complete
+        reti                          ; 28: USART1_DRE        USART1 Data Register Empty
+        reti                          ; 29: USART1_TXC        USART1 Tx Complete
         reti                          ; 30: TWI               Two-Wire-Interface
         reti                          ; 31: RESERVED          reserved
 
@@ -175,11 +174,11 @@ firmwareStart:
 
 onSystemStart:
   ; set interface number for UART0
-;  ldi r16, COMONUART0_IFACENUM
-;  sts comOnUart0_iface+NET_IFACE_OFFS_IFACENUM, r16
+  ldi r16, COMONUART0_IFACENUM
+  sts comOnUart0_iface+NET_IFACE_OFFS_IFACENUM, r16
   ; set interface number for UART1
-  ldi r16, COMONUART1_IFACENUM
-  sts comOnUart1_iface+NET_IFACE_OFFS_IFACENUM, r16
+;  ldi r16, COMONUART1_IFACENUM
+;  sts comOnUart1_iface+NET_IFACE_OFFS_IFACENUM, r16
 
   ret
 ; @end
@@ -236,7 +235,7 @@ onMessageReceived:
 ; ---------------------------------------------------------------------------
 ; defines for network interface
 
-.equ netInterfaceData = comOnUart1_iface
+.equ netInterfaceData = comOnUart0_iface
 ;.equ netInterfaceData2 = comOnUart1_iface
 
 
diff --git a/avr/modules/uart_hw2/comonuart0.asm b/avr/modules/uart_hw2/comonuart0.asm
index 2766b59..10244b4 100644
--- a/avr/modules/uart_hw2/comonuart0.asm
+++ b/avr/modules/uart_hw2/comonuart0.asm
@@ -33,15 +33,16 @@ ComOnUart0_Init:
   ldi yl, LOW(comOnUart0_iface)
   ldi yh, HIGH(comOnUart0_iface)
   rcall NET_Interface_Init                  ; (R16, R17, X)
-  ldi r16, 0xff
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
   ldi r16, UART_HW2_MODE_IDLE
   std Y+UART_HW2_IFACE_OFFS_MODE, r16
   clr r16
   std Y+NET_IFACE_OFFS_IFACENUM, r16
   rcall comOnUart0SetAttnInput
 
-  sbi COM_IRQ_ADDR_ATTN0, COM_IRQ_BIT_ATTN0 ; enable pin change irq for ATTN line
+  inr r16, COM_IRQ_ADDR_ATTN0
+  sbr r16, (1<<COM_IRQ_BIT_ATTN0)           ; enable pin change irq for ATTN line
+  outr COM_IRQ_ADDR_ATTN0, r16
+
   inr r16, GIMSK                            ; enable pin change irq PCIE0 or PCIE1
   sbr r16, (1<<COM_IRQ_GIMSK_ATTN0)
   outr GIMSK, r16
@@ -143,70 +144,6 @@ comOnUart0StartReading:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart0StartWriting
-;
-; @param Y pointer to interface data in SRAM
-; @param R16 buffer number
-; @return CFLAG set if writing started, cleared otherwise
-; @clobbers R16, R17, X, Z (R22, R24, R25)
-
-comOnUart0StartWriting:
-  push r15
-    inr r15, SREG
-    cli
-    rcall comOnUart0StartWriting_noIrq
-    brcc comOnUart0StartWriting_clc
-    outr SREG, r15
-  pop r15
-  sec
-  ret
-comOnUart0StartWriting_clc:
-    outr SREG, r15
-  pop r15
-  clc
-  ret
-
-comOnUart0StartWriting_noIrq:
-  rcall comOnUart0AcquireAttn                ; (R22)
-  brcc comOnUart0StartWriting_ebusy
-  ; copy buffer
-  rcall NET_Buffer_Locate                    ; (R17)
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
-  adiw xh:xl, NETMSG_OFFS_MSGLEN+1
-  ld r17, X
-  sbiw xh:xl, NETMSG_OFFS_MSGLEN+1
-  subi r17, -3                               ; add dest addr, msglen, crc
-  ; TODO: check size!
-  std Y+UART_HW2_IFACE_OFFS_BUFUSED, r17
-  std Y+UART_HW2_IFACE_OFFS_BUFLEFT, r17
-  ; copy into IFACE buffer
-  mov zl, yl
-  mov zh, yh
-  adiw zh:zl, UART_HW2_IFACE_OFFS_BUFFER     ; dest
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW, zl
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH, zh
-  adiw xh:xl, 1                              ; src (skip buffer header)
-comOnUart0StartWriting_loop:
-    ld r16, X+
-    st Z+, r16
-    dec r17
-  brne comOnUart0StartWriting_loop
-  ldi r16, UART_HW2_MODE_WRITING
-  rcall comOnUart0SetMode                    ; (R17)
-  rcall comOnUart0StartTx                    ; should be the last call here (R16)
-  sec
-  rjmp comOnUart0StartWriting_end
-comOnUart0StartWriting_ebusy:
-  ldi r16, NET_IFACE_OFFS_ERR_BUSY_LOW
-  rcall NET_Interface_IncCounter16           ; (R24, R25)
-  clc
-comOnUart0StartWriting_end:
-  ret
-; @end
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine ComOnUart0_Run @global
 ;
@@ -251,10 +188,7 @@ comOnUart0ModeJumpTable:
   rjmp comOnUart0RunIdle
   rjmp comOnUart0RunReading
   rjmp comOnUart0RunSkipping
-  rjmp comOnUart0RunMsgReceived
   rjmp comOnUart0RunWriting
-  rjmp comOnUart0RunWaitBufferEmpty
-  rjmp comOnUart0RunMsgSent
 ; @end
 
 
@@ -263,15 +197,48 @@ comOnUart0ModeJumpTable:
 ; @routine comOnUart0RunIdle
 ;
 ; @param Y pointer to interface data in SRAM
-; @clobbers R16, R17, R24, R25, X, Z
+; @clobbers R16, R17, R22, R24, R25, X
 
 comOnUart0RunIdle:
-  ; look for outbound message
-  rcall NET_Interface_PeekNextOutgoingMsgNum ; r16=msgNum
-  brcc comOnUart0RunIdle_end                 ; no outmsg in queue
-  rcall comOnUart0StartWriting               ; (R16, R17, R22, R24, R25, X, Z)
+  push r15
+    inr r15, SREG
+    cli
+    ; look for outbound message
+    rcall NET_Interface_PeekNextOutgoingMsgNum ; r16=msgNum
+    brcs comOnUart0RunIdle_haveMsg
+    out SREG, r15
+  pop r15
+  rjmp comOnUart0RunIdle_end
+
+comOnUart0RunIdle_haveMsg:
+    mov r24, r16
+    ldi r16, UART_HW2_MODE_WRITING
+    rcall comOnUart0SetMode                    ; (R17)
+    mov r16, r24
+    out SREG, r15
+  pop r15
+
+  push r16
+    rcall NET_Buffer_Locate                    ; (R17)
+    adiw xh:xl, 1
+    rcall comOnUart0SendMsg                    ; (R16, R17, R22, R24, R25, X)
+    push r15
+      inr r15, SREG                            ; save SREG (no CLI, we want to save CFLAG only)
+      ldi r16, UART_HW2_MODE_IDLE
+      rcall comOnUart0SetMode                  ; (R17)
+      out SREG, r15                            ; restore SREG
+    pop r15
+  pop r16
   brcc comOnUart0RunIdle_end
-  rcall NET_Interface_GetNextOutgoingMsgNum  ; take current msg off the queue
+
+  push r15
+    inr r15, SREG
+    cli
+    rcall NET_Interface_GetNextOutgoingMsgNum  ; take current msg off the queue
+    rcall NET_Buffer_ReleaseByNum              ; (R16, X)
+    out SREG, r15
+  pop r15
+  sec
 comOnUart0RunIdle_end:
   ret
 ; @end
@@ -308,12 +275,12 @@ comOnUart0RunSkipping_end:
 
 
 ; ---------------------------------------------------------------------------
-; @routine comOnUart0RunMsgReceived
+; @routine comOnUart0HandleMsgReceived
 ;
 ; @param Y pointer to interface data in SRAM
 ; @clobbers R16, R17, R18, X, Z (R19, R20, R24, R25)
 
-comOnUart0RunMsgReceived:
+comOnUart0HandleMsgReceived:
   mov xl, yl
   mov xh, yh
   adiw xh:xl, UART_HW2_IFACE_OFFS_BUFFER
@@ -371,42 +338,6 @@ comOnUart0RunWriting:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart0RunWaitBufferEmpty
-;
-; @clobbers none
-
-comOnUart0RunWaitBufferEmpty:
-  ; TODO: check for timeout etc.
-  ret
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine comOnUart0RunWriting
-;
-; @param Y pointer to interface data in SRAM
-; @clobbers R16 (R17, R22, R24, R25, X)
-
-comOnUart0RunMsgSent:
-  ldd r16, Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM
-  rcall NET_Buffer_ReleaseByNum                 ; (R16, X)
-  ldi r16, 0xff
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
-  ldi r16, NET_IFACE_OFFS_PACKETSOUT_LOW
-  rcall NET_Interface_IncCounter16              ; (R24, R25)
-  ldi r16, UART_HW2_MODE_IDLE
-  rcall comOnUart0SetMode                       ; (R17)
-  rcall comOnUart0SetAttnInput                  ; release ATTN (none)
-  rcall Utils_WaitFor10MicroSecs                ; make sure ATTN is at least high for a short period (R22)
-  ret
-; @end
-
-
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine comOnUart0AcquireAttn
 ;
@@ -467,10 +398,11 @@ comOnUart0StopRx:
 
 comOnUart0StartTx:
   inr r16, UCSR0A
-  cbr r16, (1<<TXC0)                             ; clear TXCn interrupt
+  cbr r16, (1<<TXC0)                  ; clear TXCn interrupt
   outr UCSR0A, r16
   inr r16, UCSR0B
-  sbr r16, (1<<UDRIE0) | (1<<TXCIE0) | (1<<TXEN0)  ; enable TX UDRE and TXC0 interrupt, enable transceive
+  cbr r16, (1<<UDRIE0) | (1<<TXCIE0)  ; disable TX UDRE and TXC0 interrupt, enable transceive
+  sbr r16, (1<<TXEN0)                 ; enable TX UDRE and TXC0 interrupt, enable transceive
   outr UCSR0B, r16
   ret
 ; @end
@@ -484,7 +416,7 @@ comOnUart0StartTx:
 
 comOnUart0StopTx:
   inr r16, UCSR0B
-  cbr r16, (1<<UDRIE0) | (1<<TXCIE0) | (1<<TXEN0)  ; disable TX UDRE and TXC0 interrupt, enable transceive
+  cbr r16, (1<<UDRIE0) | (1<<TXCIE0) | (1<<TXEN0)  ; disable TX UDRE and TXC0 interrupt, disable transceive
   outr UCSR0B, r16
   ret
 ; @end
@@ -506,6 +438,13 @@ comOnUart0SetAttnInput:
 .else
   cbi COM_ATTN0_OUTPUT, COM_ATTN0_PIN        ; disable pullup on ATTN
 .endif
+
+  push r16
+    inr r16, COM_IRQ_ADDR_ATTN0
+    sbr r16, (1<<COM_IRQ_BIT_ATTN0)          ; enable pin change irq for ATTN line
+    outr COM_IRQ_ADDR_ATTN0, r16
+  pop r16
+
   ret
 ; @end
 
@@ -519,8 +458,13 @@ comOnUart0SetAttnInput:
 ; @clobbers none
 
 comOnUart0SetAttnLow:
-  sbi COM_ATTN0_DDR, COM_ATTN0_PIN            ; set ATTN as output
-  cbi COM_ATTN0_OUTPUT, COM_ATTN0_PIN         ; set ATTN low
+  push r16
+    inr r16, COM_IRQ_ADDR_ATTN0
+    cbr r16, (1<<COM_IRQ_BIT_ATTN0)           ; disable pin change irq for ATTN line
+    outr COM_IRQ_ADDR_ATTN0, r16
+  pop r16
+  sbi COM_ATTN0_DDR, COM_ATTN0_PIN          ; set ATTN as output
+  cbi COM_ATTN0_OUTPUT, COM_ATTN0_PIN       ; set ATTN low
   ret
 ; @end
 
@@ -552,21 +496,29 @@ ComOnUart0_RxCharIsr:
     push r16
       push r17
         push r18
-          push r24
-            push r25
-              push xl
-                push xh
-                  push yl
-                    push yh
-                      ldi yl, LOW(comOnUart0_iface)
-                      ldi yh, HIGH(comOnUart0_iface)
-                      rcall comOnUart0RxCharIsr ; (R16, R17, R18, R24, R25, X)
-                    pop yh
-                  pop yl
-                pop xh
-              pop xl
-            pop r25
-          pop r24
+          push r19
+            push r20
+              push r24
+                push r25
+                  push xl
+                    push xh
+                      push yl
+                        push yh
+                          push zl
+                            push zh
+                              ldi yl, LOW(comOnUart0_iface)
+                              ldi yh, HIGH(comOnUart0_iface)
+                              rcall comOnUart0RxCharIsr ; (R16, R17, R18, R19, R20, R24, R25, X, Z)
+                            pop zh
+                          pop zl
+                        pop yh
+                      pop yl
+                    pop xh
+                  pop xl
+                pop r25
+              pop r24
+            pop r20
+          pop r19
         pop r18
       pop r17
     pop r16
@@ -577,62 +529,6 @@ ComOnUart0_RxCharIsr:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine ComOnUart0_TxUdreIsr @global @isr
-;
-; @clobbers none
-
-ComOnUart0_TxUdreIsr:
-  push r15
-    in r15, SREG
-    push r16
-      push r17
-        push xl
-          push xh
-            push yl
-              push yh
-                ldi yl, LOW(comOnUart0_iface)
-                ldi yh, HIGH(comOnUart0_iface)
-                rcall comOnUart0TxUdreIsr  ; (R16, R17, X)
-              pop yh
-            pop yl
-          pop xh
-        pop xl
-      pop r17
-    pop r16
-    out SREG, r15
-  pop r15
-  reti
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine ComOnUart0_TxCharIsr @global @isr
-;
-; @clobbers none
-
-ComOnUart0_TxCharIsr:
-  push r15
-    in r15, SREG
-    push r16
-      push r17
-        push yl
-          push yh
-            ldi yl, LOW(comOnUart0_iface)
-            ldi yh, HIGH(comOnUart0_iface)
-            rcall comOnUart0TxCharIsr ; (R16, R17)
-          pop yh
-        pop yl
-      pop r17
-    pop r16
-    out SREG, r15
-  pop r15
-  reti
-; @end
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine ComOnUart0AttnChangeIsr @global @isr
 ;
@@ -707,7 +603,7 @@ comOnUart0ActOnAttn_end:
 ; @routine comOnUart0RxCharIsr @global
 ;
 ; @param Y pointer to interface data in SRAM
-; @clobbers R16, R17, R18, R24, R25, X
+; @clobbers R16, R17, R18, R19, R20, R24, R25, X, Z
 
 comOnUart0RxCharIsr:
   ; check for errors
@@ -749,8 +645,8 @@ comOnUart0RxCharIsr:
   brne comOnUart0RxCharIsr_end                  ; jmp if still bytes left to receive
 comOnUart0RxCharIsr_complete:
   rcall comOnUart0StopRx
-  ldi r16, UART_HW2_MODE_MSGRECEIVED
-  rcall comOnUart0SetMode                       ; (R17)
+  rcall comOnUart0HandleMsgReceived             ; (R16, R17, R18, R19, R20, R24, R25, X, Z)
+  
   rjmp comOnUart0RxCharIsr_end
 comOnUart0RxCharIsr_hwerr:
   ldi r16, NET_IFACE_OFFS_ERR_IO_LOW
@@ -772,76 +668,54 @@ comOnUart0RxCharIsr_end:
 
 
 ; ---------------------------------------------------------------------------
-; @routine comOnUart0TxUdreIsr @global
+; @routine comOnUart0SendMsg
 ;
-; Handler for UDRE1 interrupt called when TX data register is empty.
-;
-; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_MODE)
-; @clobbers R16, R17, X
+; @param Y pointer to interface data in SRAM
+; @param X pointer to buffer to send
+; @return CFLAG set if writing started, cleared otherwise
+; @clobbers R16, R17, X (R22, R24, R25)
 
-comOnUart0TxUdreIsr:
-  inr r16, UCSR0A
-  sbrs r16, UDRE0
-    rjmp comOnUart0TxUdreIsr_disable_irq      ; not ready
-  ; check bytes left
-  ldd r17, Y+UART_HW2_IFACE_OFFS_BUFLEFT
-  tst r17
-  breq comOnUart0TxUdreIsr_finished
-  ; read byte
-  ldd xl, Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW
-  ldd xh, Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH
-  ld r16, X+
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW, xl
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH, xh
-  ; send byte
-  outr UDR0, r16                               ; send byte
-  ; decreased counter
-  dec r17
-  std Y+UART_HW2_IFACE_OFFS_BUFLEFT, r17
-  brne comOnUart0TxUdreIsr_end                ; still bytes left to send, jump
-comOnUart0TxUdreIsr_finished:
-  ldi r16, UART_HW2_MODE_WAITBUFFEREMPTY
-  rcall comOnUart0SetMode                     ; (R17)
-comOnUart0TxUdreIsr_disable_irq:
-  ; disable further DRE interrupts
-  inr r16, UCSR0B
-  cbr r16, (1<<UDRIE0)                        ; disable TX data register empty interrupt
-  outr UCSR0B, r16
-comOnUart0TxUdreIsr_end:
+comOnUart0SendMsg:
+  rcall comOnUart0AcquireAttn                ; (R22)
+  brcc comOnUart0SendMsg_ebusy
+  adiw xh:xl, NETMSG_OFFS_MSGLEN
+  ld r17, X
+  sbiw xh:xl, NETMSG_OFFS_MSGLEN
+  subi r17, -3                               ; add dest addr, msglen, crc
+  rcall comOnUart0StartTx                    ; (R16)
+  ; TODO: check size!
+  ; r17=number of bytes to write, X=buffer
+comOnUart0SendMsg_loop:
+    ; wait until transceiver ready
+      inr r16, UCSR0A
+      sbrs r16, UDRE0
+    rjmp comOnUart0SendMsg_loop
+    ; clear TXC flag by sending a 1
+    sbr r16, (1<<TXC0)
+    outr UCSR0A, r16
+    ; write byte to uart data register
+    ld r16, X+
+    outr UDR0, r16
+    dec r17
+  brne comOnUart0SendMsg_loop
+  ; wait until all data send (i.e. send buffer empty and all bits shifted out)
+comOnUart0SendMsg_loopComplete:
+    inr r16, UCSR0A
+    sbrs r16, TXC0
+  rjmp comOnUart0SendMsg_loopComplete
+  rcall comOnUart0StopTx                     ; (R16)
+  rcall comOnUart0SetAttnInput               ; release ATTN (none)
+  rcall Utils_WaitFor10MicroSecs             ; make sure ATTN is at least high for a short period (R22)
+  sec
+  rjmp comOnUart0SendMsg_end
+comOnUart0SendMsg_ebusy:
+  ldi r16, NET_IFACE_OFFS_ERR_BUSY_LOW
+  rcall NET_Interface_IncCounter16           ; (R24, R25)
+  clc
+comOnUart0SendMsg_end:
   ret
 ; @end
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart0TxCharIsr @global
-;
-; Handler for TXC0 interrupt called when the last byte has been completely sent and
-; the data register is empty.
-;
-; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_MODE)
-; @clobbers R16, R17
-
-comOnUart0TxCharIsr:
-  ; disable further TXC interrupts
-  inr r16, UCSR0B
-  cbr r16, (1<<TXCIE0)                        ; disable TXC1 interrupt
-  outr UCSR0B, r16
-  rcall comOnUart0StopTx                      ; (R16)
-  ldi r16, UART_HW2_MODE_MSGSENT
-  rcall comOnUart0SetMode                     ; (R17)
-  ret
-; @end
-
-
-
-
-
-
-
-
-
-
-
-
 #endif ; AVR_MODULES_UART_HW2_COMONUART0_H
diff --git a/avr/modules/uart_hw2/comonuart1.asm b/avr/modules/uart_hw2/comonuart1.asm
index 81d2af4..5d4e985 100644
--- a/avr/modules/uart_hw2/comonuart1.asm
+++ b/avr/modules/uart_hw2/comonuart1.asm
@@ -33,21 +33,12 @@ ComOnUart1_Init:
   ldi yl, LOW(comOnUart1_iface)
   ldi yh, HIGH(comOnUart1_iface)
   rcall NET_Interface_Init                  ; (R16, R17, X)
-  ldi r16, 0xff
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
   ldi r16, UART_HW2_MODE_IDLE
   std Y+UART_HW2_IFACE_OFFS_MODE, r16
   clr r16
   std Y+NET_IFACE_OFFS_IFACENUM, r16
-
   rcall comOnUart1SetAttnInput
 
-.ifdef COM_ATTN1_PUE
-  inr r16, COM_ATTN1_PUE
-  cbr r16, (1<<COM_ATTN1_PIN)
-  outr COM_ATTN1_PUE, r16
-.endif
-
   inr r16, COM_IRQ_ADDR_ATTN1
   sbr r16, (1<<COM_IRQ_BIT_ATTN1)           ; enable pin change irq for ATTN line
   outr COM_IRQ_ADDR_ATTN1, r16
@@ -153,84 +144,12 @@ comOnUart1StartReading:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart1StartWriting
-;
-; @param Y pointer to interface data in SRAM
-; @param R16 buffer number
-; @return CFLAG set if writing started, cleared otherwise
-; @clobbers R16, R17, X, Z (R22, R24, R25)
-
-comOnUart1StartWriting:
-  push r15
-    inr r15, SREG
-    cli
-    rcall comOnUart1StartWriting_noIrq
-    brcc comOnUart1StartWriting_clc
-    outr SREG, r15
-  pop r15
-  sec
-  ret
-comOnUart1StartWriting_clc:
-    outr SREG, r15
-  pop r15
-  clc
-  ret
-
-comOnUart1StartWriting_noIrq:
-  rcall comOnUart1AcquireAttn                ; (R22)
-  brcc comOnUart1StartWriting_ebusy
-  ; copy buffer
-  rcall NET_Buffer_Locate                    ; (R17)
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
-  adiw xh:xl, NETMSG_OFFS_MSGLEN+1
-  ld r17, X
-  sbiw xh:xl, NETMSG_OFFS_MSGLEN+1
-  subi r17, -3                               ; add dest addr, msglen, crc
-  ; TODO: check size!
-  std Y+UART_HW2_IFACE_OFFS_BUFUSED, r17
-  std Y+UART_HW2_IFACE_OFFS_BUFLEFT, r17
-  ; copy into IFACE buffer
-  mov zl, yl
-  mov zh, yh
-  adiw zh:zl, UART_HW2_IFACE_OFFS_BUFFER     ; dest
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW, zl
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH, zh
-  adiw xh:xl, 1                              ; src (skip buffer header)
-comOnUart1StartWriting_loop:
-    ld r16, X+
-    st Z+, r16
-    dec r17
-  brne comOnUart1StartWriting_loop
-  ldi r16, UART_HW2_MODE_WRITING
-  rcall comOnUart1SetMode                    ; (R17)
-  rcall comOnUart1StartTx                    ; should be the last call here (R16)
-  sec
-  rjmp comOnUart1StartWriting_end
-comOnUart1StartWriting_ebusy:
-  ldi r16, NET_IFACE_OFFS_ERR_BUSY_LOW
-  rcall NET_Interface_IncCounter16           ; (R24, R25)
-  clc
-comOnUart1StartWriting_end:
-  ret
-; @end
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine ComOnUart1_Run @global
 ;
 ; @clobbers all
 
 ComOnUart1_Run:
-  push r15
-    inr r15, SREG
-    cli
-    rcall ComOnUart1_Run_noirq
-    outr SREG, r15
-  pop r15
-  ret
-ComOnUart1_Run_noirq:
   ldi yl, LOW(comOnUart1_iface)
   ldi yh, HIGH(comOnUart1_iface)
   ldd r16, Y+UART_HW2_IFACE_OFFS_MODE
@@ -269,10 +188,7 @@ comOnUart1ModeJumpTable:
   rjmp comOnUart1RunIdle
   rjmp comOnUart1RunReading
   rjmp comOnUart1RunSkipping
-  rjmp comOnUart1RunMsgReceived
   rjmp comOnUart1RunWriting
-  rjmp comOnUart1RunWaitBufferEmpty
-  rjmp comOnUart1RunMsgSent
 ; @end
 
 
@@ -281,15 +197,48 @@ comOnUart1ModeJumpTable:
 ; @routine comOnUart1RunIdle
 ;
 ; @param Y pointer to interface data in SRAM
-; @clobbers R16, R17, R24, R25, X, Z
+; @clobbers R16, R17, R22, R24, R25, X
 
 comOnUart1RunIdle:
-  ; look for outbound message
-  rcall NET_Interface_PeekNextOutgoingMsgNum ; r16=msgNum
-  brcc comOnUart1RunIdle_end                 ; no outmsg in queue
-  rcall comOnUart1StartWriting               ; (R16, R17, R22, R24, R25, X, Z)
+  push r15
+    inr r15, SREG
+    cli
+    ; look for outbound message
+    rcall NET_Interface_PeekNextOutgoingMsgNum ; r16=msgNum
+    brcs comOnUart1RunIdle_haveMsg
+    out SREG, r15
+  pop r15
+  rjmp comOnUart1RunIdle_end
+
+comOnUart1RunIdle_haveMsg:
+    mov r24, r16
+    ldi r16, UART_HW2_MODE_WRITING
+    rcall comOnUart1SetMode                    ; (R17)
+    mov r16, r24
+    out SREG, r15
+  pop r15
+
+  push r16
+    rcall NET_Buffer_Locate                    ; (R17)
+    adiw xh:xl, 1
+    rcall comOnUart1SendMsg                    ; (R16, R17, R22, R24, R25, X)
+    push r15
+      inr r15, SREG                            ; save SREG (no CLI, we want to save CFLAG only)
+      ldi r16, UART_HW2_MODE_IDLE
+      rcall comOnUart1SetMode                  ; (R17)
+      out SREG, r15                            ; restore SREG
+    pop r15
+  pop r16
   brcc comOnUart1RunIdle_end
-  rcall NET_Interface_GetNextOutgoingMsgNum  ; take current msg off the queue
+
+  push r15
+    inr r15, SREG
+    cli
+    rcall NET_Interface_GetNextOutgoingMsgNum  ; take current msg off the queue
+    rcall NET_Buffer_ReleaseByNum              ; (R16, X)
+    out SREG, r15
+  pop r15
+  sec
 comOnUart1RunIdle_end:
   ret
 ; @end
@@ -326,12 +275,12 @@ comOnUart1RunSkipping_end:
 
 
 ; ---------------------------------------------------------------------------
-; @routine comOnUart1RunMsgReceived
+; @routine comOnUart1HandleMsgReceived
 ;
 ; @param Y pointer to interface data in SRAM
 ; @clobbers R16, R17, R18, X, Z (R19, R20, R24, R25)
 
-comOnUart1RunMsgReceived:
+comOnUart1HandleMsgReceived:
   mov xl, yl
   mov xh, yh
   adiw xh:xl, UART_HW2_IFACE_OFFS_BUFFER
@@ -389,42 +338,6 @@ comOnUart1RunWriting:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart1RunWaitBufferEmpty
-;
-; @clobbers none
-
-comOnUart1RunWaitBufferEmpty:
-  ; TODO: check for timeout etc.
-  ret
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine comOnUart1RunWriting
-;
-; @param Y pointer to interface data in SRAM
-; @clobbers R16 (R17, R22, R24, R25, X)
-
-comOnUart1RunMsgSent:
-  ldd r16, Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM
-  rcall NET_Buffer_ReleaseByNum                 ; (R16, X)
-  ldi r16, 0xff
-  std Y+UART_HW2_IFACE_OFFS_WRITEBUFNUM, r16
-  ldi r16, NET_IFACE_OFFS_PACKETSOUT_LOW
-  rcall NET_Interface_IncCounter16              ; (R24, R25)
-  ldi r16, UART_HW2_MODE_IDLE
-  rcall comOnUart1SetMode                       ; (R17)
-  rcall comOnUart1SetAttnInput                  ; release ATTN (none)
-  rcall Utils_WaitFor10MicroSecs                ; make sure ATTN is at least high for a short period (R22)
-  ret
-; @end
-
-
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine comOnUart1AcquireAttn
 ;
@@ -485,10 +398,11 @@ comOnUart1StopRx:
 
 comOnUart1StartTx:
   inr r16, UCSR1A
-  cbr r16, (1<<TXC1)                             ; clear TXCn interrupt
+  cbr r16, (1<<TXC1)                  ; clear TXCn interrupt
   outr UCSR1A, r16
   inr r16, UCSR1B
-  sbr r16, (1<<UDRIE1) | (1<<TXCIE1) | (1<<TXEN1)  ; enable TX UDRE and TXC0 interrupt, enable transceive
+  cbr r16, (1<<UDRIE1) | (1<<TXCIE1)  ; disable TX UDRE and TXC0 interrupt, enable transceive
+  sbr r16, (1<<TXEN1)                 ; enable TX UDRE and TXC0 interrupt, enable transceive
   outr UCSR1B, r16
   ret
 ; @end
@@ -502,7 +416,7 @@ comOnUart1StartTx:
 
 comOnUart1StopTx:
   inr r16, UCSR1B
-  cbr r16, (1<<UDRIE1) | (1<<TXCIE1) | (1<<TXEN1)  ; disable TX UDRE and TXC0 interrupt, enable transceive
+  cbr r16, (1<<UDRIE1) | (1<<TXCIE1) | (1<<TXEN1)  ; disable TX UDRE and TXC0 interrupt, disable transceive
   outr UCSR1B, r16
   ret
 ; @end
@@ -520,10 +434,17 @@ comOnUart1StopTx:
 comOnUart1SetAttnInput:
   cbi COM_ATTN1_DDR, COM_ATTN1_PIN           ; set ATTN as input
 .ifdef COM_ATTN1_PUE
-;  cbi COM_ATTN1_PUE, COM_ATTN_PIN            ; disable pullup on ATTN
+;  cbi COM_ATTN1_PUE, COM_ATTN_PIN           ; disable pullup on ATTN
 .else
   cbi COM_ATTN1_OUTPUT, COM_ATTN1_PIN        ; disable pullup on ATTN
 .endif
+
+  push r16
+    inr r16, COM_IRQ_ADDR_ATTN1
+    sbr r16, (1<<COM_IRQ_BIT_ATTN1)          ; enable pin change irq for ATTN line
+    outr COM_IRQ_ADDR_ATTN1, r16
+  pop r16
+
   ret
 ; @end
 
@@ -537,8 +458,13 @@ comOnUart1SetAttnInput:
 ; @clobbers none
 
 comOnUart1SetAttnLow:
-  sbi COM_ATTN1_DDR, COM_ATTN1_PIN            ; set ATTN as output
-  cbi COM_ATTN1_OUTPUT, COM_ATTN1_PIN         ; set ATTN low
+  push r16
+    inr r16, COM_IRQ_ADDR_ATTN1
+    cbr r16, (1<<COM_IRQ_BIT_ATTN1)           ; disable pin change irq for ATTN line
+    outr COM_IRQ_ADDR_ATTN1, r16
+  pop r16
+  sbi COM_ATTN1_DDR, COM_ATTN1_PIN          ; set ATTN as output
+  cbi COM_ATTN1_OUTPUT, COM_ATTN1_PIN       ; set ATTN low
   ret
 ; @end
 
@@ -570,21 +496,29 @@ ComOnUart1_RxCharIsr:
     push r16
       push r17
         push r18
-          push r24
-            push r25
-              push xl
-                push xh
-                  push yl
-                    push yh
-                      ldi yl, LOW(comOnUart1_iface)
-                      ldi yh, HIGH(comOnUart1_iface)
-                      rcall comOnUart1RxCharIsr ; (R16, R17, R18, R24, R25, X)
-                    pop yh
-                  pop yl
-                pop xh
-              pop xl
-            pop r25
-          pop r24
+          push r19
+            push r20
+              push r24
+                push r25
+                  push xl
+                    push xh
+                      push yl
+                        push yh
+                          push zl
+                            push zh
+                              ldi yl, LOW(comOnUart1_iface)
+                              ldi yh, HIGH(comOnUart1_iface)
+                              rcall comOnUart1RxCharIsr ; (R16, R17, R18, R19, R20, R24, R25, X, Z)
+                            pop zh
+                          pop zl
+                        pop yh
+                      pop yl
+                    pop xh
+                  pop xl
+                pop r25
+              pop r24
+            pop r20
+          pop r19
         pop r18
       pop r17
     pop r16
@@ -595,62 +529,6 @@ ComOnUart1_RxCharIsr:
 
 
 
-; ---------------------------------------------------------------------------
-; @routine ComOnUart1_TxUdreIsr @global @isr
-;
-; @clobbers none
-
-ComOnUart1_TxUdreIsr:
-  push r15
-    in r15, SREG
-    push r16
-      push r17
-        push xl
-          push xh
-            push yl
-              push yh
-                ldi yl, LOW(comOnUart1_iface)
-                ldi yh, HIGH(comOnUart1_iface)
-                rcall comOnUart1TxUdreIsr  ; (R16, R17, X)
-              pop yh
-            pop yl
-          pop xh
-        pop xl
-      pop r17
-    pop r16
-    out SREG, r15
-  pop r15
-  reti
-; @end
-
-
-
-; ---------------------------------------------------------------------------
-; @routine ComOnUart1_TxCharIsr @global @isr
-;
-; @clobbers none
-
-ComOnUart1_TxCharIsr:
-  push r15
-    in r15, SREG
-    push r16
-      push r17
-        push yl
-          push yh
-            ldi yl, LOW(comOnUart1_iface)
-            ldi yh, HIGH(comOnUart1_iface)
-            rcall comOnUart1TxCharIsr ; (R16, R17)
-          pop yh
-        pop yl
-      pop r17
-    pop r16
-    out SREG, r15
-  pop r15
-  reti
-; @end
-
-
-
 ; ---------------------------------------------------------------------------
 ; @routine ComOnUart1AttnChangeIsr @global @isr
 ;
@@ -701,10 +579,10 @@ ComOnUart1_HandleAttnChange:
 ; @clobbers R16 (R17, X)
 
 comOnUart1ActOnAttn:
+  ldd r16, Y+UART_HW2_IFACE_OFFS_MODE
   rcall comOnUart1IsAttnLow              ; (none)
   brcc comOnUart1ActOnAttn_attnHigh
   ; ATTN low
-  ldd r16, Y+UART_HW2_IFACE_OFFS_MODE
   cpi r16, UART_HW2_MODE_IDLE
   brne comOnUart1ActOnAttn_end           ; not idle
   rcall comOnUart1StartReading           ; (R16, R17, X)
@@ -725,7 +603,7 @@ comOnUart1ActOnAttn_end:
 ; @routine comOnUart1RxCharIsr @global
 ;
 ; @param Y pointer to interface data in SRAM
-; @clobbers R16, R17, R18, R24, R25, X
+; @clobbers R16, R17, R18, R19, R20, R24, R25, X, Z
 
 comOnUart1RxCharIsr:
   ; check for errors
@@ -767,8 +645,8 @@ comOnUart1RxCharIsr:
   brne comOnUart1RxCharIsr_end                  ; jmp if still bytes left to receive
 comOnUart1RxCharIsr_complete:
   rcall comOnUart1StopRx
-  ldi r16, UART_HW2_MODE_MSGRECEIVED
-  rcall comOnUart1SetMode                       ; (R17)
+  rcall comOnUart1HandleMsgReceived             ; (R16, R17, R18, R19, R20, R24, R25, X, Z)
+  
   rjmp comOnUart1RxCharIsr_end
 comOnUart1RxCharIsr_hwerr:
   ldi r16, NET_IFACE_OFFS_ERR_IO_LOW
@@ -790,76 +668,54 @@ comOnUart1RxCharIsr_end:
 
 
 ; ---------------------------------------------------------------------------
-; @routine comOnUart1TxUdreIsr @global
+; @routine comOnUart1SendMsg
 ;
-; Handler for UDRE1 interrupt called when TX data register is empty.
-;
-; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_MODE)
-; @clobbers R16, R17, X
+; @param Y pointer to interface data in SRAM
+; @param X pointer to buffer to send
+; @return CFLAG set if writing started, cleared otherwise
+; @clobbers R16, R17, X (R22, R24, R25)
 
-comOnUart1TxUdreIsr:
-  inr r16, UCSR1A
-  sbrs r16, UDRE1
-    rjmp comOnUart1TxUdreIsr_disable_irq      ; not ready
-  ; check bytes left
-  ldd r17, Y+UART_HW2_IFACE_OFFS_BUFLEFT
-  tst r17
-  breq comOnUart1TxUdreIsr_finished
-  ; read byte
-  ldd xl, Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW
-  ldd xh, Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH
-  ld r16, X+
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_LOW, xl
-  std Y+UART_HW2_IFACE_OFFS_BUFPOS_HIGH, xh
-  ; send byte
-  outr UDR1, r16                               ; send byte
-  ; decreased counter
-  dec r17
-  std Y+UART_HW2_IFACE_OFFS_BUFLEFT, r17
-  brne comOnUart1TxUdreIsr_end                ; still bytes left to send, jump
-comOnUart1TxUdreIsr_finished:
-  ldi r16, UART_HW2_MODE_WAITBUFFEREMPTY
-  rcall comOnUart1SetMode                     ; (R17)
-comOnUart1TxUdreIsr_disable_irq:
-  ; disable further DRE interrupts
-  inr r16, UCSR1B
-  cbr r16, (1<<UDRIE1)                        ; disable TX data register empty interrupt
-  outr UCSR1B, r16
-comOnUart1TxUdreIsr_end:
+comOnUart1SendMsg:
+  rcall comOnUart1AcquireAttn                ; (R22)
+  brcc comOnUart1SendMsg_ebusy
+  adiw xh:xl, NETMSG_OFFS_MSGLEN
+  ld r17, X
+  sbiw xh:xl, NETMSG_OFFS_MSGLEN
+  subi r17, -3                               ; add dest addr, msglen, crc
+  rcall comOnUart1StartTx                    ; (R16)
+  ; TODO: check size!
+  ; r17=number of bytes to write, X=buffer
+comOnUart1SendMsg_loop:
+    ; wait until transceiver ready
+      inr r16, UCSR1A
+      sbrs r16, UDRE1
+    rjmp comOnUart1SendMsg_loop
+    ; clear TXC flag by sending a 1
+    sbr r16, (1<<TXC1)
+    outr UCSR1A, r16
+    ; write byte to uart data register
+    ld r16, X+
+    outr UDR1, r16
+    dec r17
+  brne comOnUart1SendMsg_loop
+  ; wait until all data send (i.e. send buffer empty and all bits shifted out)
+comOnUart1SendMsg_loopComplete:
+    inr r16, UCSR1A
+    sbrs r16, TXC1
+  rjmp comOnUart1SendMsg_loopComplete
+  rcall comOnUart1StopTx                     ; (R16)
+  rcall comOnUart1SetAttnInput               ; release ATTN (none)
+  rcall Utils_WaitFor10MicroSecs             ; make sure ATTN is at least high for a short period (R22)
+  sec
+  rjmp comOnUart1SendMsg_end
+comOnUart1SendMsg_ebusy:
+  ldi r16, NET_IFACE_OFFS_ERR_BUSY_LOW
+  rcall NET_Interface_IncCounter16           ; (R24, R25)
+  clc
+comOnUart1SendMsg_end:
   ret
 ; @end
 
 
 
-; ---------------------------------------------------------------------------
-; @routine comOnUart1TxCharIsr @global
-;
-; Handler for TXC0 interrupt called when the last byte has been completely sent and
-; the data register is empty.
-;
-; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_MODE)
-; @clobbers R16, R17
-
-comOnUart1TxCharIsr:
-  ; disable further TXC interrupts
-  inr r16, UCSR1B
-  cbr r16, (1<<TXCIE1)                        ; disable TXC1 interrupt
-  outr UCSR1B, r16
-  rcall comOnUart1StopTx                      ; (R16)
-  ldi r16, UART_HW2_MODE_MSGSENT
-  rcall comOnUart1SetMode                     ; (R17)
-  ret
-; @end
-
-
-
-
-
-
-
-
-
-
-
-
 #endif ; AVR_MODULES_UART_HW2_COMONUART1_H
diff --git a/avr/modules/uart_hw2/defs.asm b/avr/modules/uart_hw2/defs.asm
index c7b0259..a50a9f6 100644
--- a/avr/modules/uart_hw2/defs.asm
+++ b/avr/modules/uart_hw2/defs.asm
@@ -17,23 +17,19 @@
 .equ UART_HW2_MODE_IDLE            = 0
 .equ UART_HW2_MODE_READING         = 1
 .equ UART_HW2_MODE_SKIPPING        = 2
-.equ UART_HW2_MODE_MSGRECEIVED     = 3
-.equ UART_HW2_MODE_WRITING         = 4
-.equ UART_HW2_MODE_WAITBUFFEREMPTY = 5
-.equ UART_HW2_MODE_MSGSENT         = 6
-.equ UART_HW2_MODE_NUM             = 7
+.equ UART_HW2_MODE_WRITING         = 3
+.equ UART_HW2_MODE_NUM             = 4
 
 
 
 .equ UART_HW2_IFACE_OFFS_BEGIN        = NET_IFACE_SIZE
 .equ UART_HW2_IFACE_OFFS_MODE         = UART_HW2_IFACE_OFFS_BEGIN
 .equ UART_HW2_IFACE_OFFS_MODECOUNTER  = UART_HW2_IFACE_OFFS_BEGIN+1
-.equ UART_HW2_IFACE_OFFS_WRITEBUFNUM  = UART_HW2_IFACE_OFFS_BEGIN+2
-.equ UART_HW2_IFACE_OFFS_BUFPOS_LOW   = UART_HW2_IFACE_OFFS_BEGIN+3
-.equ UART_HW2_IFACE_OFFS_BUFPOS_HIGH  = UART_HW2_IFACE_OFFS_BEGIN+4
-.equ UART_HW2_IFACE_OFFS_BUFUSED      = UART_HW2_IFACE_OFFS_BEGIN+5
-.equ UART_HW2_IFACE_OFFS_BUFLEFT      = UART_HW2_IFACE_OFFS_BEGIN+6
-.equ UART_HW2_IFACE_OFFS_BUFFER       = UART_HW2_IFACE_OFFS_BEGIN+7
+.equ UART_HW2_IFACE_OFFS_BUFPOS_LOW   = UART_HW2_IFACE_OFFS_BEGIN+2
+.equ UART_HW2_IFACE_OFFS_BUFPOS_HIGH  = UART_HW2_IFACE_OFFS_BEGIN+3
+.equ UART_HW2_IFACE_OFFS_BUFUSED      = UART_HW2_IFACE_OFFS_BEGIN+4
+.equ UART_HW2_IFACE_OFFS_BUFLEFT      = UART_HW2_IFACE_OFFS_BEGIN+5
+.equ UART_HW2_IFACE_OFFS_BUFFER       = UART_HW2_IFACE_OFFS_BEGIN+6
 
 .equ UART_HW2_IFACE_SIZE              = UART_HW2_IFACE_OFFS_BUFFER+UART_HW2_BUFFER_SIZE