Merge branch 'update'

docs/helios64/auto_poweron.md

@@ -0,0 +1,79 @@
+Helios64 automatic power on circuitry when main power applied to the system so user does not need to press power button.
+This is useful in case of loss of main power longer than UPS back up time. The system will automatically power on when main power return.
+
+![!Auto power on State](/helios64/img/auto-poweron/flowchart.png)
+
+U-Boot will enable Auto Power On and a [systemd-shutdown](https://www.freedesktop.org/software/systemd/man/systemd-shutdown.html) hook script to disable the Auto Power On during graceful shutdown.
+
+
+By default the system need the user to press power button to power up. This behaviour can be changed by manipulating a set of GPIOs.
+The circuitry uses [D Flip Flop](https://en.wikipedia.org/wiki/Flip-flop_(electronics)#D_flip-flop) and rely on RTC battery or UPS battery to keep the state.
+
+![!Auto Power On Schematic](/helios64/img/auto-poweron/schematic_flip_flop.png)
+
+|  State  | D     | Clock    |
+|---------|-------|-------------|
+| Enable  | 1     | Rising edge |
+| Disable | 0     | Rising edge |
+
+
+## Auto Power On Control under Linux
+
+*AUTO_ON_EN_D* pin and *AUTO_ON_EN_CLK* pin is assigned to gpio **153** and gpio **154** respectively.
+After exporting and configure the GPIOs as output (refer to [GPIO Control](/helios64/gpio/#gpio-control)), we will do bit-banging to configure the D Flip Flop.
+
+To enable the Auto Power On
+
+```
+echo 1 > /sys/class/gpio/gpio153/value
+echo 0 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 1 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 0 > /sys/class/gpio/gpio154/value
+```
+
+To disable the Auto Power On
+
+```
+echo 0 > /sys/class/gpio/gpio153/value
+echo 0 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 1 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 0 > /sys/class/gpio/gpio154/value
+```
+
+## Systemd-shutdown Script
+
+We put a script to disable Auto Power On during shutdown, located on
+
+`/lib/systemd/system-shutdown/disable_auto_poweron`.
+
+The script content:
+
+```bash
+#!/bin/bash
+
+# Export GPIO
+# AUTO_ON_D
+echo 153 > /sys/class/gpio/export
+# AUTO_EN_CLK
+echo 154 > /sys/class/gpio/export
+
+echo out > /sys/class/gpio/gpio153/direction
+echo out > /sys/class/gpio/gpio154/direction
+
+# Toggling the D Flip-Flop
+echo 0 > /sys/class/gpio/gpio153/value
+echo 0 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 1 > /sys/class/gpio/gpio154/value
+sleep 0.1
+echo 0 > /sys/class/gpio/gpio154/value
+```
+
+!!! Info
+    Current implementation does not check whether there is loss of power event.
+
+

docs/helios64/gpio.md

@@ -28,3 +28,83 @@ Helios64 provides 16 GPIOs via a 20-Pin header (P5). Those GPIOs are provided vi
 | 18  | EXP_P1_6 | |
 | 19  | EXP_P1_7 | |
 | 20  | - | GND |
+
+## Accessing GPIOs under Linux
+
+If the kernel supports debugfs (*CONFIG_DEBUG_FS=y*), list of GPIOs can be retrieved with the following command
+
+```bash
+sudo cat /sys/kernel/debug/gpio
+```
+
+Look for the **gpiochip5: GPIOs XXX-YYY** section, whereas **XXX** is first GPIO number and **YYY** is last GPIO number of IO expander.
+
+```
+gpiochip5: GPIOs 496-511, parent: i2c/2-0020, 2-0020, can sleep:   
+```
+
+Another way to get first GPIO number of the IO expander
+
+```
+cat /sys/bus/i2c/devices/2-0020/gpio/gpiochip*/base
+```
+
+Therefore the mapping between header P5 Pins and Sysfs GPIO numbers will be as described in the following table
+
+### GPIO Table
+
+| PIN | Sysfs GPIO number | Remarks |
+|-----|------|-------------|
+| 1   | - | 3.3V Supply |
+| 2   | - | 5V Supply |
+| 3   | - | GND |
+| 4   | 496 | |
+| 5   | 497 | |
+| 6   | 498 | |
+| 7   | 499 | |
+| 8   | 500 | |
+| 9   | 501 | |
+| 10  | 502 | |
+| 11  | 503 | |
+| 12  | 504 | |
+| 13  | 505 | |
+| 14  | 506 | |
+| 15  | 507 | |
+| 16  | 508 | |
+| 17  | 509 | |
+| 18  | 510 | |
+| 19  | 511 | |
+| 20  | - | GND |
+
+### GPIO Control
+
+**1.** Export the GPIO number you want to use
+
+```
+echo N | sudo tee -a /sys/class/gpio/export
+```
+
+**2.** Set the direction, "out" for Output or "in" for Input
+
+```
+echo DIRECTION | sudo tee -a /sys/class/gpio/gpioN/direction
+```
+
+**3.** Now you can read or change the GPIO value
+
+To read GPIO value
+
+```
+cat /sys/class/gpio/gpioN/value
+```
+
+To change GPIO value (only if GPIO set as Output)
+
+```
+echo VALUE | sudo tee -a /sys/class/gpio/gpioN/value
+```
+
+!!! notes
+    Pay attention to the path, /sys/class/gpio/gpio**N**/ where **N** is the GPIO number.
+
+

docs/helios64/pwm.md

@@ -35,7 +35,7 @@ The term *duty cycle* describes the proportion of 'on' time to the regular inter
 
 ## PWM Fan Connector
 
-![Fan Connector](/helios4/img/pwm/fan_connector.png)
+![Fan Connector](/helios64/img/pwm/fan_connector.png)
 
 Connector Pinout
 
@@ -45,3 +45,162 @@ Connector Pinout
 |  2  |    12V   |   Red      |
 |  3  |   Sense  |   Yellow   |
 |  4  |  Control |   Blue     |
+
+
+## Stock Fan
+
+![!Type-C Fan](/helios64/img/pwm/fan_stock_photo.jpg)
+
+Fan Specification
+
+|   Parameter   |  Value   | Unit | Remarks |
+|---------------|----------|------|---------|
+| Maximum Speed | 3600 | RPM | @ duty cycle 98% |
+| Minimum Speed | 350 | RPM | @ duty cycle 10% |
+| Shut off | Yes |  | duty cycle  < 6.5% and restart @ duty cycle > 9.5% |
+| Implementation Type | C |  |  |
+
+![!Type-C Speed Graph](/helios64/img/pwm/fan_speed_graph_stock_fan.png)
+
+!!! info
+    Duty cycle data is converted from Linux PWM
+
+## Helios64 Temperature Sensors
+
+### SoC Temperature Sensor
+
+RK3399 has internal temperature sensor (TS-ADC) for monitoring die temperature. The system has two Temperature Sensors, channel 0 is for CPU, channel 1 is for GPU.
+
+The sensor has -40~125°C temperature range and 5°C temperature resolution.
+
+### Board Temp Sensor
+
+Helios64 has a **Digital Temperature Sensor with 2‐wire Interface** ([NCT75 Datasheet](https://www.onsemi.com/pub/Collateral/NCT75-D.PDF)), located on top side of the board near RTC battery. It is used to read ambient temperature.
+
+## PWM Fan Control under Linux
+
+Linux use 8-bit integer to represent duty cycle. PWM value 0 represent 0% duty cycle and PWM value 255 represent 100% duty cycle.
+
+![Duty Cycle Formula](/helios64/img/pwm/fan_duty_cycle_formula.png)
+
+Below graphs are stock fan speed vs pwm value instead of duty cycle.
+
+![!Stock Fan Speed Graph](/helios64/img/pwm/fan_speed_graph_stock_fan_linux.png)
+
+### Using SYSFS interface
+
+Linux export the fan control mechanism to SYSFS under hwmon class.
+List of devices can be checked under /sys/class/hwmon
+
+```
+ls -l /sys/class/hwmon/
+total 0
+lrwxrwxrwx 1 root root 0 Oct 16 08:38 hwmon0 -> ../../devices/virtual/thermal/thermal_zone0/hwmon0
+lrwxrwxrwx 1 root root 0 Oct 16 08:38 hwmon1 -> ../../devices/virtual/thermal/thermal_zone1/hwmon1
+lrwxrwxrwx 1 root root 0 Oct 16 08:38 hwmon2 -> ../../devices/platform/ff120000.i2c/i2c-2/2-004c/hwmon/hwmon2
+lrwxrwxrwx 1 root root 0 Oct 16 09:29 hwmon3 -> ../../devices/platform/gpio-charger/power_supply/gpio-charger/hwmon3
+lrwxrwxrwx 1 root root 0 Oct 16 09:29 hwmon4 -> ../../devices/platform/p7-fan/hwmon/hwmon4
+lrwxrwxrwx 1 root root 0 Oct 16 09:29 hwmon5 -> ../../devices/platform/p6-fan/hwmon/hwmon5
+lrwxrwxrwx 1 root root 0 Oct 16 09:29 hwmon6 -> ../../devices/platform/ff3d0000.i2c/i2c-4/4-0022/power_supply/tcpm-source-psy-4-0022/hwmon6
+```
+
+!!! info
+    The numbering may different from above example output. It depends on whether the driver built as kernel module or built-in, device initialization order. Take this as consideration when using [fancontrol](#fancontrol-automated-software-based-fan-speed-control)
+
+To identify which hwmon belong to fan, look for *p6-fan* and *p7-fan*. On above example
+
+```
+hwmon4 -> ../../devices/platform/p7-fan/hwmon/hwmon4
+hwmon5 -> ../../devices/platform/p6-fan/hwmon/hwmon5
+```
+
+To read current PWM
+```
+cat /sys/class/hwmon4/pwm1
+cat /sys/class/hwmon5/pwm1
+```
+
+To set PWM
+```
+echo NEW_PWM_VALUE > /sys/class/hwmon4/pwm1
+echo NEW_PWM_VALUE > /sys/class/hwmon5/pwm1
+```
+
+### Fancontrol - automated software based fan speed control
+
+fancontrol is a shell script for use with lm_sensors. It reads its configuration from a file, then calculates fan speeds from temperatures and sets the corresponding PWM outputs to the computed values.
+
+```
+sudo apt-get install fancontrol
+```
+
+fancontrol includes *pwmconfig* script to create automatically a configuration file but it can not be used for Helios64.
+
+#### UDEV rules
+
+Since hwmon order can be changed between kernel version or even between reboot, on Armbian we use udev rules as workaround. The rules can be found from [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios64/90-helios64-hwmon.rules) (mainline) or [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios64/90-helios64-hwmon-legacy.rules) (legacy kernel 4.4) and to be copied to **/etc/udev/rules.d/**
+
+*/dev/fan-p6, /dev/fan-p7, /dev/thermal-cpu* and */dev/thermal-board* are symlinks generated by the udev rules.
+
+#### Configuration File
+
+fancontrol uses **/etc/fancontrol** as configuration file. Below is an example configuration to control fan speed on Helios64.
+
+```
+# Helios64 PWM Fan Control Configuration
+# Temp source : /dev/thermal-cpu
+INTERVAL=10
+FCTEMPS=/dev/fan-p6/pwm1=/dev/thermal-cpu/temp1_input /dev/fan-p7/pwm1=/dev/thermal-cpu/temp1_input
+MINTEMP=/dev/fan-p6/pwm1=40 /dev/fan-p7/pwm1=40
+MAXTEMP=/dev/fan-p6/pwm1=80 /dev/fan-p7/pwm1=80
+MINSTART=/dev/fan-p6/pwm1=20 /dev/fan-p7/pwm1=20
+MINSTOP=/dev/fan-p6/pwm1=29 /dev/fan-p7/pwm1=29
+MINPWM=20
+```
+
+INTERVAL
+
+This variable defines at which interval in seconds the main loop of fancontrol will be executed.
+
+FCTEMPS
+
+Maps PWM outputs to temperature sensors so fancontrol knows which temperature sensors should be used for calculation of new values for the corresponding PWM outputs.
+
+Fans (**fan-p6** & **fan-p7**) are controlled based on CPU thermal sensor (**thermal-cpu**) reading.
+
+MINSTART
+
+Sets the minimum speed at which the fan begins spinning. You should use a safe value to be sure it works, even when the fan gets old.
+
+Stock fan restart at 15, added 5 for safety (in case of aging fan) give us **20**.
+
+MINSTOP
+
+The minimum speed at which the fan still spins. Use a safe value here, too.
+
+Stock fan stopped at 24, added 5 for safety (in case of aging fan) give us **29**.
+
+-----
+
+*Following settings can be adjusted by user to tweak further.*
+
+MINTEMP
+
+The temperature below which the fan gets switched to minimum speed.
+
+Fans (fan-p6 & fan-p7) runs in minimum speed if the CPU temperature below **40** degree C.
+
+MAXTEMP
+
+The temperature over which the fan gets switched to maximum speed.
+
+Fans (fan-p6 & fan-p7) runs in maximum speed if the CPU temperature above **80** degree C.
+
+MINPWM
+
+The PWM value to use when the temperature is below MINTEMP. Typically, this will be either 0 if it is OK for the fan to plain stop, or the same value as MINSTOP if you don't want the fan to ever stop. If this value isn't defined, it defaults to 0 (stopped fan).
+
+!!! note
+    The Helios64 fancontrol configuration file can be found [here](https://github.com/armbian/build/blob/master/packages/bsp/helios64/fancontrol.conf).
+
+

docs/helios64/rtc.md

@@ -14,3 +14,72 @@ To save time information and allow the RTC to keep running while system is power
 
 !!! Note
     The polarity of the battery holder is indicated on the PCB with **'+'** signs.
+
+
+## Scheduled Power On using RTC
+
+User can set up a scheduled power on using RTC alarm.
+
+### Use SYSFS
+
+Run following command to check whether there is any alarm set,
+
+```bash
+cat /sys/class/rtc/rtc0/wakealarm
+```
+If nothing return, it means no alarm set.
+To reset/disable the alarm, run
+
+```bash
+echo 0 | sudo tee /sys/class/rtc/rtc0/wakealarm
+```
+
+The alarm only accept Unix epoch time. We can use *[date](https://linux.die.net/man/1/date)* utility as helper to get epoch time of our calendar.
+
+To set alarm from absolute calendar time, run
+
+```bash
+echo `date '+%s' -d '20 December 2020 02:14:10 PM'` | sudo tee /sys/class/rtc/rtc0/wakealarm
+```
+You can also set alarm from relative time using this command,
+
+```bash
+echo `date '+%s' -d '+ 1 hour 2 minutes 10 seconds'` | sudo tee /sys/class/rtc/rtc0/wakealarm
+```
+
+After alarm set, you can power off the system and keep the power plugged in. Helios64 should automatically power on at the scheduled time.
+
+### Use rtcwake
+
+Run following command to check whether there is any alarm set,
+
+```bash
+sudo rtcwake -m show
+```
+
+To reset/disable the alarm, run
+
+```bash
+sudo rtcwake -m disable
+```
+
+To set alarm from absolute calendar time, run
+
+```bash
+sudo rtcwake -m off --date '2020-12-20 14:14:10'
+```
+
+You can also set alarm from relative time using this command,
+
+```bash
+sudo rtcwake -m off --date '+ 1 hour 2 minutes 10 seconds'
+```
+
+After the command successfully executed, system will shutdown. Keep the power plugged in and Helios64 should autommatically power on at the scheduled time.
+
+## References
+
+[date- Linux manual page](https://linux.die.net/man/1/date)
+
+[rtcwake - Linux manual page](https://linux.die.net/man/8/rtcwake)
+

docs/helios64/sata.md

@@ -37,6 +37,8 @@ The power delivery of the HDDs is devided into two group:
 
 Helios64 implements a power staggering approach where *HDD Rail A* will be powered up first, then few seconds later *HDD Rail B* will be powered up. This power control scenario is performed to reduce the inrush current during disk spin-up.
 
+The power staggering mechanism is not user configurable. It is done by bootloader.
+
 ### J8 Pinout
 
 ![J8 Location](/helios64/img/sata/j8_pinout.jpg)

docs/helios64/ups.md

@@ -36,7 +36,7 @@ The battery pack is rated 7.2V 3180mAh (22.9Wh) with max continuous discharge of
 
 ## Charge Management
 
-Battery charge is fully managed by hardware, no software required. Charging function still operates when system is powered off. Helios64 board provides a visual charging indicator on LED9.
+Battery charge is fully managed by hardware ([Texas Instrument BQ24133](https://www.ti.com/product/BQ24133)), no software required. Charging function still operates when system is powered off. Helios64 board provides a visual charging indicator on LED9.
 
 |LED State | Description |
 |-----------|-------------|
@@ -45,3 +45,66 @@ Battery charge is fully managed by hardware, no software required. Charging func
 |  Blinking | Fault / Battery Absent |
 
 **Note:** The estimated time to fully charge the empty battery is around 4 hours.
+
+## UPS Status Under Linux
+
+In Linux, the UPS declared as gpio-charger located at
+`/sys/class/power_supply/gpio-charger`
+
+
+### Main Power Status
+
+Main Power status can be read using
+
+```bash
+cat /sys/class/power_supply/gpio-charger/online
+```
+
+**1** means power adapter supplying the power.
+
+**0** means loss of power, power adapter no longer supplying power.
+
+### Charging Status
+
+!!! Note
+    This status is unavailable on Linux Kernel 4.4
+
+Battery charging status can be read using
+
+```bash
+cat /sys/class/power_supply/gpio-charger/status
+```
+
+It will return **Charging** or **Not Charging**
+
+!!! Info
+    The status is only **valid** when main power is available.
+    
+    *Fault / Battery Absent* status is unavailable but it can be concluded if the status keep changing.
+
+### Battery Level
+
+Battery voltage can be measured on internal ADC channel 2. The internal ADC is located at
+`/sys/bus/iio/devices/iio:device0`
+
+![!Battery level](/helios64/img/ups/battery_level_schematic.png)
+
+
+Following table show scalling between ADC reading and actual battery voltage
+
+| Battery Voltage (V) | ADC reading (mV) | Remarks |
+|---------------------|------------------|---------|
+|  0                  |  114             | No batteries |
+|  7.0                |  916             | Recommended threshold to force shutdown system |
+|  8.4                | 1099             | Fully Charge |
+
+[IIO subsystem](https://www.kernel.org/doc/html/latest/driver-api/iio/index.html) provide hardware raw value. To convert the raw value to standard units, use following formula
+
+`adc = in_voltage2_raw * in_voltage_scale`
+
+To get the actual ADC reading in shell run following command
+
+```bash
+echo "`cat /sys/bus/iio/devices/iio:device0/in_voltage2_raw` * `cat /sys/bus/iio/devices/iio:device0/in_voltage_scale`" | bc
+```
+

docs/helios64/usb.md

@@ -109,3 +109,337 @@ Using Type-C to Type A male cable such as,
 ![Type-C to Type-A male](/helios64/img/usb/typec_typea_male.jpg)
 
 Helios64 can be used as Direct Attached Storage (DAS) with the required software configuration. It can also be used as "USB eMMC reader/writer" during system recovery mode.
+
+
+## USB under U-Boot
+
+### USB Host Port
+
+USB Host support in U-Boot is quite minimal, it only support USB storage.
+
+### USB OTG Port (USB Type-C)
+
+USB Type C port is configured as USB device mode as USB Mass Storage connected to eMMC.
+This function can be activated by pressing [Recovery Button](/helios64/button/#recovery-button).
+This is to serve as a way to (re)install OS to eMMC.
+
+## USB under Linux
+
+!!! Info
+    Currently only applicable under Linux Kernel 4.4.
+    Mainline kernel support is still under development.
+
+### Helios64 as Direct Attached Storage (DAS) device
+
+Helios64 can be used as Direct Attached Storage (DAS) device with help of Linux USB Gadget kernel module.
+
+The kernel moodule only export the underlying block device NOT the filesystem layer. Therefore if the block device is formatted with filesystem unique to Linux,
+the exported disk may not readable by computer that has Helios64 connected to.
+
+For example, the block device is formatted with EXT4 filesystem and Helios64 connected to Windows PC as DAS,
+the Windows PC will not be able to read the disk content unless 3rd party software/driver installed.
+
+
+!!! warning
+    Do NOT access Helios64 simultanouesly as DAS and NAS, as the filesystem is not managed by system and can lead to data corruption.
+
+#### Individual Disk Exported as Separate Disk
+
+To export all SATA disks that has been identified as /dev/sda ... /dev/sde, run the following command on Helios64.
+
+```
+sudo modprobe g_mass_storage file=/dev/sda,/dev/sdb,/dev/sdc,/dev/sdd,/dev/sde iSerialNumber=1234567890 iManufacturer="Kobol Innovations" iProduct=Helios64
+```
+
+The following screenshot, Helios64 connected with 5x 120GB SATA drive.
+
+***Helios64 connected to PC running Windows***
+
+USB device visualization using USB Device Tree Viewer
+![!usbtreeview Screenshot](/helios64/img/usb/linux_gadget_das_windows_usbtreeview.png)
+
+Helios64 in Device Manager
+![!device manager Screenshot](/helios64/img/usb/linux_gadget_das_windows_device_manager.png)
+
+Disks detected under Disk Management
+![!disk mgmt Screenshot](/helios64/img/usb/linux_gadget_das_windows_diskmgmt.png)
+
+***Helios64 connected to PC running Linux***
+
+USB device visualization using USBview
+![!usbview Screenshot](/helios64/img/usb/linux_gadget_das_usbview.png)
+
+USB tree using lsusb
+![!lsusb tree Screenshot](/helios64/img/usb/linux_gadget_das_lsusb_tree.png)
+
+```
+$ sudo lsusb -s 2:6 -v
+
+Bus 002 Device 006: ID 0525:a4a5 Netchip Technology, Inc. Pocketbook Pro 903
+Device Descriptor:
+  bLength                18
+  bDescriptorType         1
+  bcdUSB               3.00
+  bDeviceClass            0 (Defined at Interface level)
+  bDeviceSubClass         0 
+  bDeviceProtocol         0 
+  bMaxPacketSize0         9
+  idVendor           0x0525 Netchip Technology, Inc.
+  idProduct          0xa4a5 Pocketbook Pro 903
+  bcdDevice            4.04
+  iManufacturer           3 Kobol Innovations
+  iProduct                4 Helios64
+  iSerial                 5 1234567890
+  bNumConfigurations      1
+OTG Descriptor:
+  bLength                 3
+  bDescriptorType         9
+  bmAttributes         0x03
+    SRP (Session Request Protocol)
+    HNP (Host Negotiation Protocol)
+  Configuration Descriptor:
+    bLength                 9
+    bDescriptorType         2
+    wTotalLength           47
+    bNumInterfaces          1
+    bConfigurationValue     1
+    iConfiguration          0 
+    bmAttributes         0xe0
+      Self Powered
+      Remote Wakeup
+    MaxPower              126mA
+    Interface Descriptor:
+      bLength                 9
+      bDescriptorType         4
+      bInterfaceNumber        0
+      bAlternateSetting       0
+      bNumEndpoints           2
+      bInterfaceClass         8 Mass Storage
+      bInterfaceSubClass      6 SCSI
+      bInterfaceProtocol     80 Bulk-Only
+      iInterface              1 Mass Storage
+      Endpoint Descriptor:
+        bLength                 7
+        bDescriptorType         5
+        bEndpointAddress     0x81  EP 1 IN
+        bmAttributes            2
+          Transfer Type            Bulk
+          Synch Type               None
+          Usage Type               Data
+        wMaxPacketSize     0x0400  1x 1024 bytes
+        bInterval               0
+        bMaxBurst              15
+      Endpoint Descriptor:
+        bLength                 7
+        bDescriptorType         5
+        bEndpointAddress     0x01  EP 1 OUT
+        bmAttributes            2
+          Transfer Type            Bulk
+          Synch Type               None
+          Usage Type               Data
+        wMaxPacketSize     0x0400  1x 1024 bytes
+        bInterval               0
+        bMaxBurst              15
+Binary Object Store Descriptor:
+  bLength                 5
+  bDescriptorType        15
+  wTotalLength           22
+  bNumDeviceCaps          2
+  USB 2.0 Extension Device Capability:
+    bLength                 7
+    bDescriptorType        16
+    bDevCapabilityType      2
+    bmAttributes   0x00000006
+      Link Power Management (LPM) Supported
+  SuperSpeed USB Device Capability:
+    bLength                10
+    bDescriptorType        16
+    bDevCapabilityType      3
+    bmAttributes         0x00
+    wSpeedsSupported   0x000f
+      Device can operate at Low Speed (1Mbps)
+      Device can operate at Full Speed (12Mbps)
+      Device can operate at High Speed (480Mbps)
+      Device can operate at SuperSpeed (5Gbps)
+    bFunctionalitySupport   1
+      Lowest fully-functional device speed is Full Speed (12Mbps)
+    bU1DevExitLat           1 micro seconds
+    bU2DevExitLat         500 micro seconds
+Device Status:     0x0000
+  (Bus Powered)
+
+```
+
+xfce file manager (thunar)
+![!Thunar Screenshot](/helios64/img/usb/linux_gadget_das_thunar_5_drive.png)
+
+lsblk output:
+```
+$ lsblk
+NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
+sdc      8:32   0 111,8G  0 disk 
+└─sdc1   8:33   0 111,8G  0 part 
+sdd      8:48   0 111,8G  0 disk 
+└─sdd1   8:49   0 111,8G  0 part 
+sde      8:64   0 111,8G  0 disk 
+└─sde1   8:65   0 111,8G  0 part 
+sdf      8:80   0 111,8G  0 disk 
+└─sdf1   8:81   0 111,8G  0 part 
+sdg      8:96   0 111,8G  0 disk 
+└─sdg1   8:97   0 111,8G  0 part 
+
+$ lsblk -S
+NAME HCTL       TYPE VENDOR   MODEL             REV TRAN
+sda  0:0:0:0    disk ATA      WDC WDS240G2G0B  0000 sata
+sdb  1:0:0:0    disk ATA      TOSHIBA MQ04     0J   sata
+sdc  2:0:0:0    disk Linux    File-Stor Gadget 0404 usb
+sdd  2:0:0:1    disk Linux    File-Stor Gadget 0404 usb
+sde  2:0:0:2    disk Linux    File-Stor Gadget 0404 usb
+sdf  2:0:0:3    disk Linux    File-Stor Gadget 0404 usb
+sdg  2:0:0:4    disk Linux    File-Stor Gadget 0404 usb
+```
+
+#### RAID device exported as One Disk
+
+Assuming the RAID already created and identified as /dev/md/md-raid6, run the following command on Helios64 to export the RAID block device as USB Mass Storage
+
+```
+sudo modprobe g_mass_storage file=/dev/md/md-raid6 iManufacturer="Kobol Innovations" iProduct="Helios64" iSerialNumber="1234567890"
+```
+
+The following screenshot, Helios64 connected with 5x 120GB SATA drive and configured as RAID 6 so total space of the block device is ~360GB (3x 120GB). The block device then formatted with NTFS.
+
+***Helios64 connected to PC running Windows***
+
+USB device visualization using USB Device Tree Viewer
+![!usbtreeview Screenshot](/helios64/img/usb/linux_gadget_das_windows_usbtreeview_raid.png)
+
+Helios64 in Device Manager
+![!device manager Screenshot](/helios64/img/usb/linux_gadget_das_windows_device_manager_raid.png)
+
+Disks detected under Disk Management
+![!disk mgmt Screenshot](/helios64/img/usb/linux_gadget_das_windows_diskmgmt_raid.png)
+
+!!! note
+	Since the block device is formatted with NTFS, Windows can recognize it and assign drive letter E:
+
+***Helios64 connected to PC running Linux***
+
+USB device visualization using USBview
+![!usbview Screenshot](/helios64/img/usb/linux_gadget_das_usbview_raid.png)
+
+USB tree using lsusb
+![!lsusb tree Screenshot](/helios64/img/usb/linux_gadget_das_lsusb_tree_raid.png)
+
+```
+Bus 002 Device 006: ID 0525:a4a5 Netchip Technology, Inc. Pocketbook Pro 903
+Device Descriptor:
+  bLength                18
+  bDescriptorType         1
+  bcdUSB               3.00
+  bDeviceClass            0 (Defined at Interface level)
+  bDeviceSubClass         0 
+  bDeviceProtocol         0 
+  bMaxPacketSize0         9
+  idVendor           0x0525 Netchip Technology, Inc.
+  idProduct          0xa4a5 Pocketbook Pro 903
+  bcdDevice            4.04
+  iManufacturer           3 Kobol Innovations
+  iProduct                4 Helios64
+  iSerial                 5 1234567890
+  bNumConfigurations      1
+OTG Descriptor:
+  bLength                 3
+  bDescriptorType         9
+  bmAttributes         0x03
+    SRP (Session Request Protocol)
+    HNP (Host Negotiation Protocol)
+  Configuration Descriptor:
+    bLength                 9
+    bDescriptorType         2
+    wTotalLength           47
+    bNumInterfaces          1
+    bConfigurationValue     1
+    iConfiguration          0 
+    bmAttributes         0xe0
+      Self Powered
+      Remote Wakeup
+    MaxPower              126mA
+    Interface Descriptor:
+      bLength                 9
+      bDescriptorType         4
+      bInterfaceNumber        0
+      bAlternateSetting       0
+      bNumEndpoints           2
+      bInterfaceClass         8 Mass Storage
+      bInterfaceSubClass      6 SCSI
+      bInterfaceProtocol     80 Bulk-Only
+      iInterface              1 Mass Storage
+      Endpoint Descriptor:
+        bLength                 7
+        bDescriptorType         5
+        bEndpointAddress     0x81  EP 1 IN
+        bmAttributes            2
+          Transfer Type            Bulk
+          Synch Type               None
+          Usage Type               Data
+        wMaxPacketSize     0x0400  1x 1024 bytes
+        bInterval               0
+        bMaxBurst              15
+      Endpoint Descriptor:
+        bLength                 7
+        bDescriptorType         5
+        bEndpointAddress     0x01  EP 1 OUT
+        bmAttributes            2
+          Transfer Type            Bulk
+          Synch Type               None
+          Usage Type               Data
+        wMaxPacketSize     0x0400  1x 1024 bytes
+        bInterval               0
+        bMaxBurst              15
+Binary Object Store Descriptor:
+  bLength                 5
+  bDescriptorType        15
+  wTotalLength           22
+  bNumDeviceCaps          2
+  USB 2.0 Extension Device Capability:
+    bLength                 7
+    bDescriptorType        16
+    bDevCapabilityType      2
+    bmAttributes   0x00000006
+      Link Power Management (LPM) Supported
+  SuperSpeed USB Device Capability:
+    bLength                10
+    bDescriptorType        16
+    bDevCapabilityType      3
+    bmAttributes         0x00
+    wSpeedsSupported   0x000f
+      Device can operate at Low Speed (1Mbps)
+      Device can operate at Full Speed (12Mbps)
+      Device can operate at High Speed (480Mbps)
+      Device can operate at SuperSpeed (5Gbps)
+    bFunctionalitySupport   1
+      Lowest fully-functional device speed is Full Speed (12Mbps)
+    bU1DevExitLat           1 micro seconds
+    bU2DevExitLat         500 micro seconds
+Device Status:     0x0000
+  (Bus Powered)
+```
+
+xfce file manager (thunar)
+![!Thunar Screenshot](/helios64/img/usb/linux_gadget_das_thunar_raid.png)
+
+lsblk output
+```
+$ lsblk
+NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
+sdc      8:32   0 335,2G  0 disk 
+└─sdc1   8:33   0 335,2G  0 part 
+
+$ lsblk -S
+NAME HCTL       TYPE VENDOR   MODEL             REV TRAN
+sda  0:0:0:0    disk ATA      WDC WDS240G2G0B  0000 sata
+sdb  1:0:0:0    disk ATA      TOSHIBA MQ04     0J   sata
+sdc  2:0:0:0    disk Linux    File-Stor Gadget 0404 usb
+```
+

mkdocs.yml

@@ -93,13 +93,15 @@ nav:
     - Jumper: 'helios64/jumper.md'
     - LED: 'helios64/led.md'
     - M.2: 'helios64/m2.md'
-    - PMIC: 'helios64/pmic.md'
+    - Power:
+      - Auto Power On: 'helios64/auto_poweron.md'
+      - PMIC: 'helios64/pmic.md'
+      - UPS Battery: 'helios64/ups.md'
     - PWM Fan: 'helios64/pwm.md'
     - RTC: 'helios64/rtc.md'
     - SATA: 'helios64/sata.md'
     - SPI: 'helios64/spi.md'
     - UEXT: 'helios64/uext.md'
-    - UPS Battery: 'helios64/ups.md'
     - USB: 'helios64/usb.md'
   - Documents: 'helios64/docs.md'
 - Helios4: