MSP430G2755: UART UCA0TXIFG interrupt is triggering even though UCA0TXIE is not enabled?

David Koss

Part Number: MSP430G2755

This occurs when I turn on the interrupts for the UCB0TXIE for SPI communications ( UART is on UCA0). Curious as why this interrupt is firing despite UCA0TXIE is not enabled. Maybe something that occurs in DEBUG mode only?

Here is a screenshot of the registers

over 4 years ago

0 David Koss over 4 years ago

Intellectual 290 points

0 Bruce McKenney47378 over 4 years ago

Guru 89760 points

TXIFG is automatically set as part of the SWRST sequence, including power-up. [Ref User Guide (SLAU144J) Sec 16.3.1] It won't cause an actual interrupt (ISR call) unless TXIE is set.

More generally, in the MSP430 IFGs are set independent of their corresponding IEs. It's routine to have IFGs set for events you're not interested in.

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MSP430G2755: UART UCA0TXIFG interrupt is triggering even though UCA0TXIE is not enabled?