a Launchpad MSP-EXP430FR4133 should work as a custom digital watch, possibly with a time drift <5’ a year. The time will be displayed on the LCD when button P1 is pressed.
At the same time, the Lauchpad should serve a serial interrupt because periodically (say once a month) the device will exchange data with a PC application.
All of this should be operated in ultra-low energy mode so that a battery will last as long as possible (one year or longer).
Are these concurrent features possible ?
Somebody says that ultra-low energy mode is possible for a Launchpad only if RX and TX onboard jumpers are set to OFF, but I hope that Mr. Doom is wrong