Software management of power supply

The power management state is the full-speed working state and the sleep state with the lowest power consumption. Therefore, the main task of power management is to switch between the full-speed working state and the sleep state in a timely manner to achieve the purpose of saving power. The specific design idea is to generate a kernel daemon thread when the system is initialized. The thread checks the system status at regular intervals. If the system is in an idle state for a period of time greater than the preset value, the assembly instruction is called to put the system into sleep until the user operates to wake it up.

1. Wake up

When the user tries to wake up the system, ARM needs to go through a wake-up process to recover from the Sleep state to the normal working state. The initial actions of this process are the same as the normal Reset process.

After adding these codes, the system can be woken up from sleep state normally.

2. Switch to sleep mode

The main functions are to save the stack address, clear the data cache, set the memory to self-refresh state, etc. When all steps are completed in order, execute:

Put the system into sleep mode.

3. Voltage collection

Voltage acquisition is a simple program that allows the system to track the current voltage conditions.

The OSTimeDly() function is used in the data acquisition task Vo_Sampling_Task() to implement a 4-beat delay, that is, the task is executed once every 4×0.5=2ms, which ensures a sampling rate of 20ms for sampling 10 points.