/*! \page page_octoclock OctoClock

\tableofcontents

\section octoclock_features Feature list

- Hardware Capabilities:
    -   Fully integrated timing source with 8-Way distribution (10 MHz and 1 PPS)
    -   User selection between internal GPSDO (when present) or external 10 MHz/1 PPS source
    -   Ethernet bootloader for easy firmware upgrade
    -   Source detection with automatic switch over in case of failure or disconnect
    -   Streaming GPS time and NMEA strings over Ethernet (OctoClock-G only)

\section octoclock_load Loading Firmware onto the Octoclock

First, the OctoClock's bootloader needs to be loaded onto the device. Connect the AVR programmer to J108, as
specified on the <a href="http://files.ettus.com/schematics/octoclock/octoclock.pdf">schematics</a>. Once you
verify that the programmer is properly connected, run the following commands to load the bootloader:

    cd <install path>/share/uhd/images
    avrdude -p atmega128 -c <programmer name> -P usb -U efuse:w:0xFF:m -U hfuse:w:0x80:m -U lfuse:w:0xEF:m -U flash:w:octoclock_r4_fw.hex:i

When the bootloader is loaded, it will have a default IP address of `192.168.10.3`.

\b Note:
On Linux, `sudo avrdude ...` might be necessary to gain access to the programmer.

\section octoclock_network Setting Up Networking

\subsection host_interface Setting up the host interface

The OctoClock communicates with the host machine at the UDP layer over Ethernet. The default device
of the OctoClock is `192.168.10.3`. You will need to configure the host machine's Ethernet interface with
a static IP address to enable communication. An address of `192.168.10.1` and a subnet mask of
`255.255.255.0` is recommended.

\b Note:
When using UHD software, if an IP address for the OctoClock is not specified, the software will
use UDP broadcast packets to locate the OctoClock. On some systems, the firewall will block UDP broadcast
packets. It is recommended that you change your firewall settings.

\subsection changing_ip Changing the OctoClock's IP address

You may need to change the OctoClock's IP address for various reasons.

- To satisfy your particular network configuration
- To use multiple OctoClocks on the same host computer

To change the OctoClock's IP address, run the following commands (using the default IP address as an example):

    cd <install path>/lib/uhd/utils
    ./octoclock_burn_eeprom --args="<optional device args>" --values="ip-addr=192.168.10.3"

\section addressing Addressing the Device

There are two ways to address the OctoClock from UHD software: the IP address, and the serial.

To use the IP address, address it as follows:

    "addr=<ip address>"

If you want to use multiple OctoClock devices, address it as follows:

    "addr0=<ip address 1>,addr1=<ip address 2>"

To use the serial, address it as follows:

    "serial=<serial>"

\section hardware_setup Hardware Setup Notes

\subsection front_panel_leds Front Panel LEDs

The LEDs on the front panel show the current status of the device. Each LED is described below:

- **Internal:** the device is using the internal GPSDO
- **External:** the device is using an external reference
- **Status:** the device is successfully distributing a 10 MHz and PPS signal
- **PPS:** lights up when a PPS signal is detected
- **GPS Lock:** the internal GPSDO has achieved a lock (not necessary to distribute the signals)
- **Power:** the device is receiving power

\subsection front_panel_switch Front Panel Switch

The front panel switch, marked **Primary Ref** determines which reference the OctoClock will prefer to use. If it is receiving
both an internal and external reference, the device will use whichever one the switch specifies.

However, if it is only receiving an internal reference, it will use this reference no matter what position the switch is in.
The same applies for an external signal.

\section misc Miscellaneous

\subsection available_sensors Available Sensors

The following sensors are available on both the OctoClock and Octoclock-G; these can be queried through the
<a href="classuhd_1_1octoclock.html">API</a>.

- `ext_ref_detected:` whether or not the device detects an external reference
- `gps_detected:` whether or not the device detects an internal GPSDO
- `using_ref:` which reference the device is using (internal or external)
- `switch_pos:` the position of the front switch (internal or external)

On the OctoClock-G, the following sensors are added:

- `gps_gpgga:` the latest GPGGA string sent by the GPSDO
- `gps_gprmc:` the latest GPRMC string sent by the GPSDO
- `gps_time:` the time reported by the GPSDO
- `gps_locked:` whether or not the GPSDO is locked (true/false)
- `gps_servo:` the latest debug trace information sent by the GPSDO

*/