docs(rock5b): note 40-pin header has no power-on/wake-up signal

docs/rock5/rock5b/hardware-design/hardware-interface.md

@@ -171,6 +171,14 @@ description: "详细介绍 ROCK 5B/5B+ 硬件信息"
 
 </Tabs>
 
+:::note 40-pin 排针不提供开机 / 唤醒信号
+
+ROCK 5B/5B+ 的 40-pin 排针没有引出 PMIC 的开机信号（PWRON），也没有引出唤醒信号，因此**无法通过 40-pin 上的引脚实现外部硬件开机或唤醒**。该触发信号只存在于 PMIC 部分电路，没有连接到 40-pin 排针。
+
+如果需要由外部电路控制开机，可以控制输入到板子的 5V / USB-PD 电源；给 40-pin 的 5V（PIN 2 / PIN 4）通电可以让板子启动，但这属于电源上电，并不是由引脚控制的开机触发。
+
+:::
+
 ### Gigabit Ethernet
 
 - ROCK 5B/5B+

i18n/en/docusaurus-plugin-content-docs/current/rock5/rock5b/hardware-design/hardware-interface.md

@@ -171,6 +171,14 @@ description: "Detailed hardware information for ROCK 5B/5B+"
 
 </Tabs>
 
+:::note No power-on / wake-up signal on the 40-pin header
+
+The 40-pin header on ROCK 5B/5B+ does not expose the PMIC power-on signal (PWRON), nor any wake-up signal, so **an external hardware power-on or wake-up cannot be implemented through a pin on the 40-pin header**. That trigger signal exists only in the PMIC circuit and is not routed to the 40-pin header.
+
+If you need to control power-on from external circuitry, switch the 5V / USB-PD supply that feeds the board. Applying 5V to the 40-pin 5V pins (PIN 2 / PIN 4) will start the board, but that is a supply power-up, not a pin-controlled power-on trigger.
+
+:::
+
 ### Gigabit Ethernet
 
 - ROCK 5B/5B+