# Interrupts on the MSP430¶

Currently (version 6.5 and up) only the MSP430 G2553 has some preliminary support for interrupt service routines written in high level Forth. Most of the words from the AVR world work exactly the same way:

The ISR support is disabled by default. To enable it, edit the application master file and add the following line to it

.set WANT_INTERRUPTS = 1


Now rebuild and reflash the controller. Be aware of the additional code space requirements and a slightly slower overall system speed.

Currently only the G2553 supports this system. Unlike the AVR world, not every index of the ISR table is used actually, so a mapping is used to minimize the code space usage.

 Index Mapping G2553 1 Port 1 IO 2 Port 2 IO 3 ADC IO 4 UCSI Transmit 5 UCSI Receive 6 Timer A CC1 7 Timer A CC0 8 Comparator A 9 Timer B CC1 10 Timer B CC0

The XT table is stored in the Info Flash. To keep it permanently, use the SAVE command. All ISR have the default action noop and do nothing at all.