Hi there,

I have finally managed to successfully upload a HEX file onto an AT89S8252 using SP89, but now I am having difficulties with the timer 2 capture interrupt. The following code was made just to see if I could get the interrupt to work, but it won't.



Initial: LJMP Start

ORG 0034h
Start: MOV T2CON, #0Dh ;Setup timer 2
SETB EA ;Enable interrupts
SETB ET2 ;Enable timer 2 interrupt

EN EQU P3.3
RW EQU P3.4
RS EQU P3.5
DATA EQU P2

INIT_LCD: MOV A, #38h
LCALL LCD_COMMAND
MOV A, #0Eh
LCALL LCD_COMMAND
MOV A, #06h
LCALL LCD_COMMAND

LCALL CLEAR_LCD
MOV A, #'A'
LCALL LCD_WRITE
MOV A, #'B'
LCALL LCD_WRITE
MOV A, #'C'
LCALL LCD_WRITE
MOV A, #':'
LCALL LCD_WRITE

Mainloop:

; Writing numbers to the LCD

MOV A, #85h
LCALL LCD_COMMAND
MOV A, #01h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #02h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #03h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #04h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #05h
ADD A, #30h
LCALL LCD_WRITE

LJMP Mainloop

;Interrupts

ORG 002Bh
LCALL Overflow_int
RETI

ORG 0FAh

Overflow_int: JNB TF2, Capture_int
CLR TF2
RET

Capture_int: CLR EXF2

PUSH ACC

MOV A, #0C0h
LCALL LCD_COMMAND
MOV A, #03h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #03h
ADD A, #30h
LCALL LCD_WRITE
MOV A, #03h
ADD A, #30h
LCALL LCD_WRITE
POP ACC

RET


;Subroutines

LCD_COMMAND: CLR RS
CLR RW
MOV DATA, A
SETB EN
NOP
NOP
NOP
NOP
CLR EN
LCALL WAIT_LCD
RET

WAIT_LCD: CLR RS
SETB RW
MOV DATA, #0FFh
SETB EN
MOV A, DATA
JB ACC.7, WAIT_LCD
CLR EN
CLR RW
RET

CLEAR_LCD: MOV A, #01h
LCALL LCD_COMMAND
RET

LCD_WRITE: SETB RS
CLR RW
MOV DATA, A
SETB EN
NOP
NOP
NOP
NOP
CLR EN
LCALL WAIT_LCD
RET


END


All this code is meant to do is display 'ABC: 12345' on the top line of the display permanently and then '333' on the bottom line of the display when the timer 2 interrupt is caused by a 1-0 transition on P1.1, which means that EXF2 flag must be set. When I use the simulator that is built into Pinnacle 52, the timer 2 interrupt is always called when the TF2 flag is set due to timer 2 overflowing - this is correct. However, when I play around with P1.1 (T2EX) in the ports window, it never triggers an interrupt, which is what I need it to do. I have also put this program onto the actual MCU and tried to get it to display '333' but it won't trigger the interrupt. I get the 'ABC: 12345' to work properly, but no interrupt.

Can anyone see any obvious flaws in my program? The MCU is an AT89S8252.

Regards
Warren

BTW, the obove section of program was made purely to test this interrupt and is a modified section from another program , so if it seems a bit cumbersome and strange, that is the reason...