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# <a name="LV2 Launch Tower Relay (LTR) Boa"></a> LV2 Launch Tower Relay (LTR) Board

<div>
  <center>
    <p><a href="http://photos.psas.pdx.edu/avionics/ltr_board_2005_08_04.jpg"> <img alt="ltr_board_2005_08_04.thumb.jpg" src="http://psas.pdx.edu/albums/avionics/ltr_board_2005_08_04.thumb.jpg"> </a><br><font size="-1"> <em>Launch Tower Relay (LTR) board as of August 4th, 2005</em> </font></p>
  </center>
</div>

**Overview:** This board has a PIC18F458 (running [[PicCore]]) which runs four relays in the launch tower electronics box and interfaces to the [[LTC|Lv2LaunchTowerComputer]] via the CAN bus. It also has some analog ports available for thermistors, and a lot of expansion room for daughterboards and whatnot.

## <a name="Hardware Notes."></a> Hardware Notes.

Attached below are the Schematic and board layout, in [EAGLE CAD](http://www.cadsoft.de) and PDF.

<table border=1 cellpadding=0 cellspacing=0>
  <tr>
    <td> Relay 1 </td>
    <td> LATD0 </td>
    <td> Ignition relay </td>
  </tr>
  <tr>
    <td> Relay 2 </td>
    <td> LATD1 </td>
    <td> Shore power relay </td>
  </tr>
  <tr>
    <td> Relay 3 </td>
    <td> LATD2 </td>
    <td> Strobe relay </td>
  </tr>
  <tr>
    <td> Relay 4 </td>
    <td> LATD3 </td>
    <td> Siren relay </td>
  </tr>
</table>

We didn't end up using any of the thermistor ports, but we really should in order to keep track of the temperature in the box (don't want stuff frying in there).

## <a name="Firmware Notes"></a> Firmware Notes

Firmware for the node can be found at: <http://cvs.psas.pdx.edu/cgi-bin/cvsweb/c/firmware/ltr/>

Before any relays can be turned on, you need to arm the board via a CAN message; see the readme file in the firmware directory for CAN message IDs.

## <a name="Project Notes"></a> Project Notes

<table border=1 cellpadding=0 cellspacing=0>
  <tr>
    <th bgcolor="#99CCCC"><strong> Date </strong></th>
    <th bgcolor="#99CCCC"><strong> Notes </strong></th>
  </tr>
  <tr>
    <td> 08/04/2005 </td>
    <td> Replaced ignition relay with a new SPST relay... and fixed burned out (!!!) trace. Cut traces which would have shorted out new SPST contacts. Moved LEDs to a high efficiency, clear LEDs with plastic tubes around them for better viewing. Used a 10k pulldown on PIC sense of old SPDT relay. </td>
  </tr>
  <tr>
    <td> 03/24/2004 </td>
    <td> Posted page. Posted schematics. Ver 0 vs Ver 1? As below, we&#39;ll call 1.0 the first board run. </td>
  </tr>
  <tr>
    <td> 08/14/2003 </td>
    <td> Version 1.0: WARNING, PCB HAS ERRORS. The DRC wasn&#39;t checked because of the number of misc. inconsequential problems: some traces actually touch and thus are shorted on the board. Also, the ICD2 connector has somehow - astoundingly - been mirrored. See the readme.txt file. </td>
  </tr>
</table>

----
Attachments:

- [[ltr_board_layout_v1.pdf]]
- [[ltr_schematic_v1.pdf]]
- [[relay-board-v1.brd]]
- [[relay-board-v1.sch]]