avr: added com2w2 (slightly improved version of com2w).

- move IRQ control to main code (only the main code knows exactly which
  combination of pins is used for com2)
- split one big module into multiple smaller files (easier to maintain)

avr/modules/com2w2/bytewrite.asm

@@ -0,0 +1,76 @@
+; ***************************************************************************
+; copyright   : (C) 2026 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+#ifndef AVR_MODULES_COM2W2_BYTEWRITE_H
+#define AVR_MODULES_COM2W2_BYTEWRITE_H
+
+
+.cseg
+
+
+
+; ---------------------------------------------------------------------------
+; @routine com2w2SendBytes
+;
+; @param  R18 number of bytes to send
+; @param X pointer to bytes to send
+; @param Y pointer to interface data in SRAM
+; @clobbers: r16, r18, X (r17, r22)
+
+com2w2SendBytes:
+com2w2SendBytes_loop:
+    rcall com2w2ClkSetLow                     ; (none)
+    rcall com2w2WaitTime1                      ; longer wait period (R22)
+    ld r16, X+
+    rcall com2w2SendByte                      ; (R16, R17, R22)
+    dec r18
+  brne com2w2SendBytes_loop
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine com2w2SendByte
+;
+; @param  R16 byte to send
+; @clobbers: r16, r17 (r22)
+
+com2w2SendByte:
+  push r15
+    in r15, SREG
+    ldi r17, 8
+com2w2SendByte_loop:
+      M_COM2WCLKSETLOW
+      out SREG, r15                          ; probably enable irqs
+      rcall com2w2WaitTime1                  ; wait for longer time (R22)
+      lsr r16
+      brcs com2w2SendByte_send1
+      M_COM2WDATASETLOW
+      rjmp com2w2SendByte_sent
+com2w2SendByte_send1:
+      M_COM2WDATASETHIGH
+com2w2SendByte_sent:
+      Utils_WaitNanoSecs 5000, 0, r22        ; wait for very short time to ensure data is stable when clock rises
+      cli                                    ; ensure time period by disabling irqs
+      M_COM2WCLKSETHIGH
+      rcall com2w2WaitTime2                  ; wait for shorter time (R22)
+      dec r17
+    brne com2w2SendByte_loop
+    out SREG, r15
+  pop r15
+  rcall com2w2WaitTime2                      ; wait for shorter time (R22)
+  M_COM2WDATASETHIGH                         ; ensure data line is high
+  ret
+; @end
+
+
+
+#endif
+