From adcb037976bd0dc2bf5fb5ffcb1e801de2913e1a Mon Sep 17 00:00:00 2001
From: Martin Preuss <martin@aquamaniac.de>
Date: Sun, 6 Oct 2024 01:30:52 +0200
Subject: [PATCH] avr: fixed 1-wire protocol for multiple speeds.

fixed delays won't work with 8MHz when calibrated for 1MHz... use
wait macro instead.
---
 avr/modules/ds18b20/main.asm   |  4 +--
 avr/modules/owimaster/main.asm | 47 ++++++++++++++++++++++------------
 2 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/avr/modules/ds18b20/main.asm b/avr/modules/ds18b20/main.asm
index ff53409..b63605d 100644
--- a/avr/modules/ds18b20/main.asm
+++ b/avr/modules/ds18b20/main.asm
@@ -136,7 +136,7 @@ Ds18b20_OnTimer_done:
 Ds18b20_SendCommand:
   mov r18, r16
   
-  rcall OwiMaster_Reset           ; (r22)
+  rcall OwiMaster_Reset           ; (r21, r22)
   tst r16                         ; presence detected?
   breq Ds18b20_SendCommand_error  ; nope, jump
 
@@ -166,7 +166,7 @@ Ds18b20_SendCommand_error:
 ; @clobbers r16, r18, r19, r23, X (r17, r20, r21, r22)
 
 Ds18b20_ReadRom:
-  rcall OwiMaster_Reset           ; (r22)
+  rcall OwiMaster_Reset           ; (r21, r22)
   tst r16                         ; presence detected?
   breq Ds18b20_ReadRom_error      ; nope, jump
 
diff --git a/avr/modules/owimaster/main.asm b/avr/modules/owimaster/main.asm
index f4fe71b..78e3920 100644
--- a/avr/modules/owimaster/main.asm
+++ b/avr/modules/owimaster/main.asm
@@ -36,7 +36,7 @@ OwiMaster_Init:
 ; Cave: Needs interrupts to be disabled!
 ;
 ; @return r16 0xff if slave presence signal received, 0x00 otherwise
-; @clobbers r22
+; @clobbers r21, r22
 
 OwiMaster_Reset:
   ; send RESET pulse (min. 480usec)
@@ -47,15 +47,30 @@ OwiMaster_Reset:
   rcall Utils_WaitFor100MicroSecs
   rcall Utils_WaitFor100MicroSecs
   rcall Utils_WaitFor100MicroSecs
-  cbi OWI_DDR, OWI_PINNUM     ; set to input
-
+  cbi OWI_DDR, OWI_PINNUM         ; set to input
+  ; after 16-60 uS slave pulls line low for 60-240 uS
   ; if present slave pulls line low for 60 usecs (we check after 30 usecs)
-  Utils_WaitNanoSecs 30000, 0, r22
-  clr r16
-  sbic OWI_PORTIN, OWI_PINNUM
-    rjmp OwiMaster_Reset_done
-  dec r16
-  rcall owiWaitForDataState1ms ; wait for line pulled up
+  ldi r21, 100
+OwiMaster_Reset_LoopWaitForLow:          ; wait for line low
+    Utils_WaitNanoSecs 5000, 0, r22
+    sbis OWI_PORTIN, OWI_PINNUM
+      rjmp OwiMaster_Reset_isLow
+    dec r21
+  brne OwiMaster_Reset_LoopWaitForLow
+  clr r16                      ; not present
+  rjmp OwiMaster_Reset_done
+OwiMaster_Reset_isLow:
+  ldi r21, 160
+OwiMaster_Reset_LoopWaitForHigh:          ; wait for line high
+    Utils_WaitNanoSecs 5000, 0, r22
+    sbic OWI_PORTIN, OWI_PINNUM
+      rjmp OwiMaster_Reset_isHigh
+    dec r21
+  brne OwiMaster_Reset_LoopWaitForHigh
+  clr r16                      ; not present
+  rjmp OwiMaster_Reset_done
+OwiMaster_Reset_isHigh:
+  ldi r16, 0xff                ; presence detected
 OwiMaster_Reset_done:
   ret
 ; @end
@@ -75,16 +90,16 @@ OwiMaster_SendByte:
   cbi OWI_PORTOUT, OWI_PINNUM        ; set value to zero
   ldi r21, 8
 OwiMaster_SendByte_loop:
-    sbi OWI_DDR, OWI_PINNUM          ; set to output
-    lsr r16                          ; bit to send -> CARRY
-    brcs OwiMaster_SendByte_setHigh
+    sbi OWI_DDR, OWI_PINNUM          ; set to output (pull line low)
+    lsr r16                          ; +1 bit to send -> CARRY
+    brcs OwiMaster_SendByte_setHigh  ; +1 / +2
 OwiMaster_SendByte_setLow:
-    Utils_WaitNanoSecs 60000, 0, r22 ; set to low for 60 usecs ("0")
-    cbi OWI_DDR, OWI_PINNUM          ; set to output
-    Utils_WaitNanoSecs 5000, 0, r22  ; set to low for 5 usecs ("1")
+    Utils_WaitNanoSecs 60000, 0, r22 ; low for 60 usecs
+    cbi OWI_DDR, OWI_PINNUM          ; set to input (pulls line high)
+    Utils_WaitNanoSecs 5000, 0, r22  ; wait for 5 usecs
     rjmp OwiMaster_SendByte_loopEnd
 OwiMaster_SendByte_setHigh:
-    Utils_WaitNanoSecs 5000, 0, r22  ; set to low for 5 usecs ("1")
+    Utils_WaitNanoSecs 5000, 0, r22  ; keep low for 5 usecs
     cbi OWI_DDR, OWI_PINNUM          ; set to output
     Utils_WaitNanoSecs 60000, 0, r22 ; keep high for remainder of write slot
 OwiMaster_SendByte_loopEnd: