USRP Hardware Driver and USRP Manual  Version: 003.008.003-0-g87dfdc3c
UHD and USRP Manual
OctoClock

Table of Contents

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
    • Source detection with automatic switch over in case of failure or disconnect
    • Streaming GPS time and NMEA strings over Ethernet (OctoClock-G only)

Loading Firmware onto the Octoclock

OctoClock bootloader

If you purchased your OctoClock device before Ethernet functionality was introduced, or if your unit's bootloader has somehow become corrupted, you must burn the bootloader onto the device before you can load the primary firmware.

To load the bootloader onto the OctoClock, two things are needed:

  • AVR programmer
  • AVRdude software

Connect the AVR programmer to J108, as specified on the schematics. Once you verify that the programmer is properly connected, run the following commands to burn the firmware: 

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:0xFF:m -U flash:w:octoclock_bootloader.hex:i

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

Once the bootloader has been burned, power-cycle your OctoClock device and refer to the below instructions on burning the OctoClock's primary firmware.

Primary Octoclock firmware

To load firmware onto the OctoClock, you must use the octoclock_firmware_burner utility, specifying the IP address of the OctoClock device, as follows: 

octoclock_firmware_burner --addr=192.168.10.3

Setting Up Networking

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.

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.

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"

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>"

Hardware Setup Notes

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

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.

Miscellaneous

Available Sensors

The following sensors are available on both the OctoClock and Octoclock-G; these can be queried through the API.

  • 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