David Vanhorn's Watchdog.asm
Watchdog timer example code
Watchdog timer example code
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;*************************************************************************** ; ; File Name :'Watchdog.asm" ; Title : ; Date : ; Version : ; Support telephone :765 287 1987 David B. VanHorn ; Support fax :765 287 1989 ; Support Email :dvanhorn@cedar.net ; Target MCU :AT90S8515 ; ;***************************************************************************; ; M O D I F I C A T I O N H I S T O R Y ; ; ; rev. date who why ; ---- -------- --- ------------------------------------------ ; 0.01 98.07.29 dvh Creation ; ;******************************************************************** ; Timed_Smack: ;Whatever you need to satisfy the internal or external watchdog ;The internal watchdog can be set to 16,32,64,128,256,512,1024,or 2048mS ;This scheme for timed reset is limited to 255mS between resets, but it can ;be used with any of the timeouts above. Resetting a watchdog more frequently ;than is needed, is mostly harmless. ;Just make sure that the value you set the timer to at the end of INIT is ;GREATER than the value you assign for Dog_Chow in EQUATES.INC ;The code to set the watchdog to a particular interval is in INIT.ASM lds TEMP,Dog_Food ;How many milliseconds before reset is needed? and TEMP,TEMP ;Is it zero? brne Smack_Done ;Nope, just exit ldi TEMP,Dog_Chow ;Reload the timer for the next occurence sts Dog_Food,TEMP ; wdr;This code will reset the internal watchdog ldi TEMP,$0D ;000XXXXX Reserved ;XXX0XXXX Watchdog turnoff enable ;XXXX1XXX Watchdog enable bit 1=enable ;XXXXX000 (8) Watchdog timeout, 16mS ;XXXXX001 (9) Watchdog timeout. 32mS ;XXXXX010 (A) Watchdog timeout. 64mS ;XXXXX011 (B) Watchdog timeout. 128mS ;XXXXX100 (C) Watchdog timeout, 256mS ;XXXXX101 (D) Watchdog timeout, 512mS ;XXXXX110 (E) Watchdog timeout,1024mS ;XXXXX111 (F) Watchdog timeout,2048mS out WDTCR,TEMP ; Smack_Done: ret |