Driver: Power Management¶
1 功能概述¶
本例程演示通过 Zephyr Power Management (PM) 机制进出低功耗的方法。
2 环境要求¶
PAN1080 EVB 一块
电流计（本文使用电流可视化测量设备 PPK2 [Nordic Power Profiler Kit II] 进行演示）
USB-TypeC 线一条（用于供电和查看串口打印 Log）
硬件接线：
使用 USB 线，将 PC USB 与 EVB USB-TypeC（USB->UART）相连
根据 EVB 核心板芯片的封装不同，使用杜邦线将 EVB 底板上的:
TX0 与 P00 相连， RX0 与 P01 相连（若 EVB 板芯片为 QFN32 或 LQFP64 封装）
TX0 与 P30 相连， RX0 与 P31 相连（若 EVB 板芯片为 QFN48 封装）
PC 软件: 串口调试助手（UartAssist）或终端工具（SecureCRT），波特率921600
3 编译和烧录¶
例程位置：zephyr\samples_panchip\drivers\pm
使用 ZAL 工具可以对其进行编译、烧录、打开 VS Code 调试等操作。关于 ZAL 工具的详细介绍请参考：Zephyr APP Launcher 工具介绍。
4 演示说明¶
程序烧录完成后，从串口工具中看到如下的打印信息：
Try to load HW calibration data.. DONE. - Chip Type : 0x80 - Chip CP Version : None - Chip FT Version : 5 - Chip MAC Address : D0000C0293CA - Chip Flash UID : 31373237300A29494330FFFFFFFFFFFF - Chip Flash Size : 1024 KB *** Booting Zephyr OS build zephyr-v2.7.0-1347-g4073b5da347f *** Reset Reason: NVIC System Reset. Sleep 100ms to enter zephyr pm cpu-idle state.. Waked up from zephyr cpu-idle state. Sleep 300ms to enter zephyr pm runtime-idle state.. Waked up from zephyr runtime-idle state. Sleep 600ms to enter zephyr pm suspend-to-idle state.. Waked up from zephyr suspend-to-idle state. Sleep 900ms to enter zephyr pm suspend-to-ram state.. Try to load HW calibration data.. DONE. - Chip Type : 0x80 - Chip CP Version : None - Chip FT Version : 5 - Chip MAC Address : D0000C0293CA - Chip Flash UID : 31373237300A29494330FFFFFFFFFFFF - Chip Flash Size : 1024 KB *** Booting Zephyr OS build zephyr-v2.7.0-1347-g4073b5da347f *** Reset Reason: Waked up from zephyr suspend-to-ram state. Sleep 1600ms to enter zephyr pm soft-off state..
由上述 Log 可得知以下信息：
第一次芯片 Reset 原因为 NVIC System Reset，这是因为本次芯片是程序烧录后由 JLink 触发的软件 Reset
接着系统进入持续 100ms 的
cpu-idle状态，此状态对应芯片的 Sleep 模式从
cpu-dle状态唤醒后，系统又进入持续 300ms 的runtime-idle状态，此状态同样对应芯片的 Sleep 模式从
runtime-dle状态唤醒后，系统又进入持续 600ms 的suspend-to-idle状态，此状态对应芯片的 DeepSleep 模式从
suspend-to-dle状态唤醒后，系统又进入持续 900ms 的suspend-to-ram状态，此状态对应芯片的 Standby M1 (with SRAM Retention) 模式从
suspend-to-ram状态唤醒后，系统复位，此次 Reset 原因显示为 Waked up from zephyr suspend-to-ram state然后芯片进入了持续 1600ms（实际上是无限时间）的
soft-off状态，此状态对应芯片的 Standby M0 模式，只能通过 GPIO P56 引脚唤醒
按一下 EVB 底板上的 WKUP (P56) 按键，由串口打印信息可知触发了芯片唤醒：
Try to load HW calibration data.. DONE. - Chip Type : 0x80 - Chip CP Version : None - Chip FT Version : 5 - Chip MAC Address : D0000C0293CA - Chip Flash UID : 31373237300A29494330FFFFFFFFFFFF - Chip Flash Size : 1024 KB *** Booting Zephyr OS build zephyr-v2.7.0-1347-g4073b5da347f *** Reset Reason: Waked up from zephyr soft-off state. Sleep 100ms to enter zephyr pm cpu-idle state.. Waked up from zephyr cpu-idle state. Sleep 300ms to enter zephyr pm runtime-idle state.. Waked up from zephyr runtime-idle state. Sleep 600ms to enter zephyr pm suspend-to-idle state.. Waked up from zephyr suspend-to-idle state. Sleep 900ms to enter zephyr pm suspend-to-ram state.. Try to load HW calibration data.. DONE. - Chip Type : 0x80 - Chip CP Version : None - Chip FT Version : 5 - Chip MAC Address : D0000C0293CA - Chip Flash UID : 31373237300A29494330FFFFFFFFFFFF - Chip Flash Size : 1024 KB *** Booting Zephyr OS build zephyr-v2.7.0-1347-g4073b5da347f *** Reset Reason: Waked up from zephyr suspend-to-ram state. Sleep 1600ms to enter zephyr pm soft-off state..
由上述 Log 可得知以下信息：
本次芯片 Reset 原因为 Waked up from zephyr soft-off state.
接着芯片重复进入各个低功耗模式，最终再次停在
soft-off状态等待下一次 P56 按键唤醒
5 开发者说明¶
5.2 进入低功耗的时机¶
&cpu0 {
cpu-power-states = <&state0 &state1 &state2 &state3>;
};
&state0 {
compatible = "zephyr,power-state";
power-state-name = "runtime-idle";
min-residency-us = <200000>;
exit-latency-us = <32>;
};
&state1 {
compatible = "zephyr,power-state";
power-state-name = "suspend-to-idle";
min-residency-us = <500000>;
exit-latency-us = <32>;
};
&state2 {
compatible = "zephyr,power-state";
power-state-name = "suspend-to-ram";
min-residency-us = <800000>;
exit-latency-us = <32>;
};
&state3 {
compatible = "zephyr,power-state";
power-state-name = "soft-off";
min-residency-us = <1500000>;
exit-latency-us = <32>;
};
以该参数来说明：
cpu0 有四种低功耗状态，分别为
state0:
runtime-idle（sleep mode）state1:
suspend-to-idle（deepsleep mode）state2:
suspend-to-ram（standby mode1）state3:
soft-off（standby mode0）
如果idle时间满足以下条件：
if (time_to_next_scheduled_event >= (state.min_residency_us + state.exit_latency))) {
return state
}
则进入相应的state。
6 RAM/Flash资源使用情况¶
Memory region Used Size Region Size %age Used
FLASH: 19880 B 384 KB 5.06%
SRAM: 6952 B 64 KB 10.61%