========================================================================
UHD - USRP-E1X0 Series Application Notes
========================================================================

.. contents:: Table of Contents

------------------------------------------------------------------------
Comparative features list
------------------------------------------------------------------------

* 1 transceiver card slot
* 2 RX DDC chains in FPGA
* 1 TX DUC chain in FPGA
* Timed commands in FPGA
* Timed sampling in FPGA
* Internal PPS reference
* Internal 10MHz reference
* Configurable clock rate (defaults 64 MHz)
* Internal GPSDO option
* sc8 and sc16 sample modes

------------------------------------------------------------------------
Specify a Non-standard Image
------------------------------------------------------------------------
UHD will automatically select the USRP-Embedded FPGA image from the
installed images package.  The FPGA image selection can be overridden with the
**--fpga=** device address parameter.

Example device address string representations to specify non-standard FPGA
image:

::

    fpga=usrp_e100_custom.bin

------------------------------------------------------------------------
Changing the Master Clock Rate
------------------------------------------------------------------------
The master clock rate of the USRP-Embedded feeds both the FPGA DSP and the codec
chip.  Hundreds of rates between 32MHz and 64MHz are available.  A few notable
rates are:

* **64MHz:** maximum rate of the codec chip
* **61.44MHz:** good for UMTS/WCDMA applications
* **52Mhz:** good for GSM applications

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Set 61.44MHz - uses external VCXO
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
To use the 61.44MHz clock rate with the USRP-Embedded, two jumpers must be moved
on the device.

* **J16** is a two pin header; remove the jumper (or leave it on pin1 only).
* **J15** is a three pin header; move the jumper to (pin1, pin2).

**Note:** See instructions below to communicate the desired clock rate UHD.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Set other rates - uses internal VCO
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
To use other clock rates, the jumpers will need to be in the default position.

* **J16** is a two pin header; move the jumper to (pin1, pin2).
* **J15** is a three pin header; move the jumper to (pin2, pin3).

To communicate the desired clock rate into UHD,
specify the a special device address argument,
where the key is **master_clock_rate** and the value is a rate in Hz.
Example:
::

    uhd_usrp_probe --args="master_clock_rate=52e6"

------------------------------------------------------------------------
Clock Synchronization
------------------------------------------------------------------------


^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Ref Clock - 10MHz
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The E1xx has a 10MHz TCXO which can be used to discipline the flexible clocking
by selecting **REF_INT** for the **clock_config_t**.

Alternately, an external 10MHz reference clock can be supplied by soldering
a connector.

* Connector **J10** (REF_IN) needs MCX connector **WM5541-ND** or similar.
* Square wave will offer the best phase noise performance, but sinusoid is acceptable.
* **Power level:** 0 to 15dBm
* Select **REF_SMA** in **clock_config_t**.


^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
PPS - Pulse Per Second
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
An exteral PPS signal for timestamp synchronization can be supplied by soldering
a connector.

* Connector **J13** (PPS) needs MCX connector **WM5541-ND** or similar.
* Requires a square wave signal.
* **Amplitude:** 3.3 to 5Vpp

Test the PPS input with the following app:

* **<args** are device address arguments (optional if only one USRP is on your machine).

::

    cd <install-path>/share/uhd/examples
    ./test_pps_input --args=<args>

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Internal GPSDO
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Please see the `Internal GPSDO Application Notes <./gpsdo.html>`_
for information on configuring and using the internal GPSDO.

UHD will always try to detect an installed GPSDO at runtime.
There is not a special EEPROM value to burn for GPSDO detection.

------------------------------------------------------------------------
Hardware Setup Notes
------------------------------------------------------------------------

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Front panel LEDs
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The LEDs on the front panel can be useful in debugging hardware and software
issues.  The LEDs reveal the following about the state of the device:

* **LED A:** transmitting
* **LED B:** PPS signal
* **LED C:** receiving
* **LED D:** fpga loaded
* **LED E:** reference lock
* **LED F:** board power

------------------------------------------------------------------------
Miscellaneous
------------------------------------------------------------------------

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Available Sensors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The following sensors are available;
they can be queried through the API.

* **ref_locked:** clock reference locked (internal/external)
* other sensors are added when the GPSDO is enabled