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Target: ST uPSD3454 running at 36.8864 Mhz
What seems simple is causing extreme confusion.
Enhanced template code from Keil:
; Define instructions executed on a hardware timer interrupt. HW_TIMER_CODE MACRO EXTRN CODE (TIMER_Update) USING 2 ; Registerbank 2 for following code LCALL TIMER_Update ; C-func RETI ENDM
C-func:
void TIMER_Update( void ) { unsigned char data i; for( i=0; i<NUM_TIMERS; i++ ) { timers[i]--; if( timers[i] == 0 ) { timers[i] = reload[i]; if( events[i] < 255 ) events[i]++; } } }
HW_TIMER_CODE is ISR and occurring ever 10ms. TIMER_update is attempt to implement software timers for additional systems functionality.
After about the 3rd HW_TIMER_CODE execution (between 30 and 50ms) system resets.
No stack corruption is detected in trace.
What silly thing am I overlooking?
By using the declaration
void TIMER_Update( void ) using 2 { ... }
C51 is intelligent enough to generate
PUSH PSW MOV PSW,#010H ... POP PSW RET
as a wrapper around the C-func.
RTX51 Tiny is sharing RegBank 0, but the RTOS timer interrupt is using RegBank 1. Therefore, the declaration in the C-func of using 2 was specified to let the compiler keep track of the used / unused registers of RegBank 2.
All appears to be working correctly now. Thanks for the insights.
(I agree with both "I hate macros. All of them." and "I prefer interrupt handler in "C" style."!)