.. _dig_optical_rev06:

==============================
Digital Optical 14Tx4Rx Rev06
==============================

.. image:: optical_14tx4rx_rev06/14TX4RX_Rev6.png
   :width: 600

Functionality
-------------
* Transmits up to 14 optical signals, e.g. gate signals. 
* Receives up to 4 optical signals, e.g. error signals. 
* LEDs on PCB signaling the state of the transmitter/receiver

Logic table
-----------
The underlying logic is that 

* Logic HIGH = LED/Transmitter/Receiver ON
* Logic LOW = LED/Transmitter/Receiver OFF

Transmitter Logic 
""""""""""""""""""

.. image:: optical_14tx4rx_rev06/sch_tx.jpg
   :width: 600
   
   
.. list-table:: Logic table transmitter 
   :widths: 25 25 25 25
   :header-rows: 1

   * - GATE
     - Node Tx_N
     - Transmitter LED U1
     - LED D1
   * - LOW
     - HIGH
     - OFF
     - OFF
   * - HIGH
     - LOW
     - ON
     - ON

Receiver Logic 
"""""""""""""""

.. image:: optical_14tx4rx_rev06/sch_rx.jpg
   :width: 800

.. list-table:: Logic table receiver 
   :widths: 25 25 25 25
   :header-rows: 1

   * - Receiver Diode U3
     - Node RxTx
     - Signal
     - LED D2
   * - Light OFF
     - HIGH
     - LOW
     - OFF
   * - Light ON
     - LOW
     - HIGH
     - ON

Before first use
----------------

Soldering 
"""""""""
Solder in up to 

* 14 optical transmitters: **Broadcom HFBR-1521Z**
* 4 optical receiver: **Broadcom HFBR-2521Z**

Please refer to this page for detailed :ref:`dig_optical_soldering`.

.. note::
     Note that transmitters and receivers with even numbers are on the top side, starting to count from 0, to match with Vivado vector logic. While the uneven numbers are on the bottom side.

Program CPLDs 
"""""""""""""
Program CPLDs with firmware, see :ref:`label_cpld_programming` for details. Note, that the signals are simply passed through the CPLD. Optionally, additional functionality can be implemented in the CPLD, e.g. checking for invalid switching combinations or introducing a dead time.


Additional features
""""""""""""""""""""""
Manual rework allows to exchange the 4 receiver channels to 4 transmitter channels, resulting in up to 18 transmitter channels, check Schematic and Assembly Drawing at the end of this page for the necessary changes.

Known issues
------------
No known issues

Compatibility 
-------------
* Only compatible with **CarrierBoard Rev04 and later**, since the edge-connector has no chamfer (angle). 
* Slots D1 to D4 can be used without limitations, if CPLD is programmed correctly

Optical Cables 
--------------
* Optical Cables of type **HFBR-RNSxxxZ** are tested and recommended for transmitting the optical signals. The **xxx** determines the length of the cable in meters.

References
----------
* :download:`Schematic 14Tx4Rx <optical_14tx4rx_rev06/SCH_Digital_Optical_14Tx4Rx_Rev06.pdf>`
* :download:`Assembly Drawing 14Tx4Rx <optical_14tx4rx_rev06/ASM_Digital_Optical_14Tx4Rx_Rev06.pdf>`
* :download:`Schematic 18Tx <optical_14tx4rx_rev06/SCH_Digital_Optical_18Tx_Rev06.pdf>`
* :download:`Assembly Drawing 18Tx <optical_14tx4rx_rev06/ASM_Digital_Optical_18Tx_Rev06.pdf>`
* :ref:`label_cpld_programming`


Designed by 
"""""""""""""""
Eugen Romanschenko (TUM), Eyke Liegmann (TUM) in 04/2021