Application note use case

AN4515

18/24

DocID026482 Rev 1

Figure 13. Startup and Configuration Menu

4.

The system wakes up from Stop mode and enter SLEEP2 state waiting for the user to

select the desired configuration.

5.

Once the configuration is selected, an external interrupt on USART2_RX wakes up the

CPU from Sleep mode.

6.

The CPU enters Sleep mode again (SLEEP3 state) while a DMA transfers message is

sent via USART2.

7.

After a DMA transfer complete interrupt has been received, the CPU configures the

MEMS and enters SLEEP4 state waiting for an accelerometer movement (UP or

DOWN direction). The DMA sends the ### Move MEMS UP or DOWN ### message

during Sleep mode.

Figure 14. Wait MEMS movement while CPU is Sleep mode

and Flash memory stopped

8.

After the MEMS has moved, the CPU wakes up from Sleep mode, configures the I2C

interface and DMA to transfer samples coming from the MEMS. The DMA then starts