| NHPOW(4) | Kernel Interfaces Manual (Sandpoint) | NHPOW(4) | 
nhpow also detects a soft power-off condition, which is triggered by holding the front panel power button pressed for several seconds. This driver can optionally invoke powerd(8) to get a finer control over the system shutdown procedure. It is capable of reporting a power-button-pressed event. Refer to the powerd(8) manual section for more details.
The nhpow driver provides access to its 8 bidirectional GPIO pins through the gpio(4) controller interface. The pins have the following meaning when being written:
| Pin | Active level | Function | 
| 0 | high | System power off | 
| 1 | high | Assert system reset to all devices | 
| 2 | low | Status LED | 
| 3 | high | High speed fan | 
| 4 | low | Debug LED 1 | 
| 5 | low | Debug LED 2 | 
| 6 | low | USB port 1 LED | 
| 7 | low | USB port 2 LED | 
When reading, the pins have the following meaning:
| Pin | Active level | Function | 
| 0 | low | Power button pressed | 
| 1 | low | Reset/install button pressed | 
| 4 | high | H/W version bit 0 | 
| 5 | high | H/W version bit 1 | 
| 6 | high | H/W version bit 2 | 
| 7 | high | H/W version bit 3 | 
nhpow attaches automatically for all NH-230/231 compatible products:
| January 15, 2012 | NetBSD 7.1 |