Texas Instruments MSP430x1xx User Manual page 333

I2CIV, Interrupt Vector Generator
The I
vector. The interrupt vector register I2CIV is used to determine which flag
requested an interrupt. The highest priority enabled interrupt generates a
number in the I2CIV register that can be evaluated or added to the program
counter to automatically enter the appropriate software routine. Disabled I
interrupts do not affect the I2CIV value. When RXDMAEN = 1, RXRDYIFG will
not affect the I2CIV value and when TXDMAEN = 1, TXRDYIFG will not affect
the I2CIV value, regardless of the state of RXRDYIE or TXRDYIE.
Any access, read or write, of the I2CIV register automatically resets the highest
pending interrupt flag. If another interrupt flag is set, another interrupt is
immediately generated after servicing the initial interrupt.
I2CIV Software Example
The following software example shows the recommended use of I2CIV. The
I2CIV value is added to the PC to automatically jump to the appropriate routine.
I2C_ISR
STTIFG_ISR
ALIFG_ISR
NACKIFG_ISR
OAIFG_ISR
ARDYIFG_ISR
RXRDYIFG_ISR
TXRDYIFG_ISR
GCIFG_ISR
2
C interrupt flags are prioritized and combined to source a single interrupt
ADD &I2CIV, PC
RETI
JMP ALIFG_ISR
JMP NACKIFG_ISR ; Vector 4: NACKIFG
JMP OAIFG_ISR
JMP ARDYIFG_ISR ; Vector 8: ARDYIFG
JMP RXRDYIFG_ISR ; Vector 10: RXRDYIFG
JMP TXRDYIFG_ISR ; Vector 12: TXRDYIFG
JMP GCIFG_ISR
...
RETI
...
RETI
...
RETI
...
RETI
...
RETI
...
RETI
...
RETI
...
RETI
USART Peripheral Interface, I
2
I C Module Operation
; Add offset to jump table
; Vector 0: No interrupt
; Vector 2: ALIFG
; Vector 6: OAIFG
; Vector 14: GCIFG
; Vector 16
; Task starts here
; Return
; Vector 2
; Task starts here
; Return
; Vector 4
; Task starts here
; Return
; Vector 6
; Task starts here
; Return
; Vector 8
; Task starts here
; Return
; Vector 10
; Task starts here
; Return
; Vector 12
; Task starts here
; Return
; Vector 14
; Task starts here
; Return
2
C Mode
2
C
15-19