Because the low power mode is used, the timer should be turned off at this time, otherwise the processor will be woken up frequently. However, it needs to write to the iic storage device AT24C02 immediately after waking up, and it needs to delay 2ms. At this time, the timer has not been started, which will lead to an infinite loop.
Therefore, in this scenario, we must find a way to avoid using the timer to delay.