Low Energy UART is a peripheral that also works in EM2 (deep sleep mode). Communication can be performed while the CPU core is sleeping. It can also work with DMA (which can work with EM2). See AN0017 (Low Energy UART) for details.

■Usage example
Set the power mode to EM2, stop the CPU core, and wait for data with the Low Energy UART. When data is received and the buffer becomes full, it can be transferred to memory using DMA, and then the CPU core wakes up to perform processing. Since the period during which the CPU core is stopped can be maximized, current consumption can be suppressed.