Wake EFM8UB1/EFM8BB2 Devices from Snooze Mode with SPI
03/90/2017 | 12:13 AM
In Table 1.1 of the BB2/UB1 datasheets, the device lists the capability to be awakened from snooze mode by SPI0 activity. The SPI is also described with the feature that it "Can operate in suspend or snooze modes and wake the CPU on reception of a byte." What is required for this to work?
Firstly, the device must be in slave mode. Secondly, the Read Request Interrupt Enable bit (RFRQE) in the SPI0 FIFO Control 0 register (SPI0FCN0) must be set. It is not necessary to use the SPI with interrupts in order for this to work.