These application use cases show MCU to SPI peripherals with bi-directional wake-up from the MCU side or the peripheral side.

Figure 2-1 example shows MCU to SPI peripheral with bi-directional wake up. When both sides idle the communication by returning both INC and IND to HIGH, the isolator transitions to STANDBY state and turns off the high-speed data channels. When the MCU wants to communicates, the MCU pulls INC LOW (nCS) and the isolator wakes-up, turns on the high-speed channels and pulls OUTC LOW. The SPI peripheral uses the input from OUTC as a wake-up interrupt or equivalent to wake-up and prepare for the high-speed communication. Similarly, if the system is in low-power mode and the peripheral issues a wake-up request, the peripheral pulls IND (nWAKE) LOW. The isolator wakes-up, and turns on the high-speed channels and asserts OUTD LOW. The MCU uses an interrupt IO or equivalent on OUTD to wake-up and prepare for the high-speed communication.

The next example, Figure 2-2, is similar to Figure 2-1 however this example uses multiple SPI peripherals in a point to point SPI architecture.