To measure the current draw of the MSP430FR5994 using a multimeter, use the 3V3 jumper on the J101 jumper isolation block. The current measured includes the target device and any current drawn through the BoosterPack plug-in module headers.
To measure ultra-low power, follow these steps:
- Remove the 3V3 jumper in the J101 isolation block, and attach an ammeter across this jumper.
- Consider the effect that the backchannel UART and any circuitry attached to the MSP430FR5994 may have on current draw. Consider disconnecting these at the isolation jumper block, or at least consider their current sinking and sourcing capability in the final measurement.
- Make sure there are no floating inputs or outputs (I/Os) on the MSP430FR5994. These cause unnecessary extra current draw. Every I/O should either be driven out or, if it is an input, should be pulled or driven to a high or low level.
- Begin target execution.
- Measure the current. Keep in mind that if the current levels are fluctuating, it may be difficult to get a stable measurement. It is easier to measure quiescent states.
Alternatively, EnergyTrace++ technology can be used to measure the same current, and see energy profiles through integrated GUI in CCS and IAR. EnergyTrace allows you to compare various current profiles and better optimize the energy performance.