====== Pmod LS1 Reference Manual ======
The Digilent Pmod LS1 (Revision B) allows users to receive signals from multiple optical sensors, such as the popular combination of an IR LED with an IR sensor used in line-following robots.

{{Digilent Image Gallery 
| image = {{:reference:pmod:pmodls1:pmodls1-0.png?direct |}}
| image = {{:reference:pmod:pmodls1:pmodls1-1.png?direct |}}
| image = {{:reference:pmod:pmodls1:pmodls1-2.png?direct |}}
| image = {{:reference:pmod:pmodls1:pmodls1-3.png?direct |}}
}} 

== Download This Reference Manual == 
  * {{:reference:pmod:pmodls1:pmodls1_rm.pdf| PDF}}

----

===== Features =====
  * Infrared light detector with on-board sensitivity adjustment
  * Interface with up to four reflective or transmissive photo detectors
  * Works with Digilent IR Proximity Sensor
  * 6-pin Pmod connector with %%GPIO%% interface

----
=====Functional Description =====
The %%Pmod LS1%% is designed to be used with up to four sensors containing an infrared %%LED%% and an infrared-sensitive photo-transistor, such as the [[https://digilent.com/shop/ir-proximity-sensor-2-pack/|IR Proximity Sensor available from Digilent]]. When using Digilent’s sensors, refer to the print on the board indicating the wire color for the correct orientation of the wire. If third-party sensors are used, refer to the  board schematic available at [[http://www.digilent.com/Data/Products/PMOD-LS1/PmodLS1_sch.pdf|www.digilent.com]] for the proper connection of the %%LED%% and photo-transistor. 

The module uses analog comparators to determine when the infrared detectors have sensed more infrared light than the threshold limit. The sensitivity of the sensors can be adjusted by adjusting the onboard potentiometer. 

----
===== Interfacing with the Pmod=====
The %%Pmod LS1%% communicates with the host board via the [[pmod:communication_protocols:gpio|GPIO]] protocol. By the Pmod design, each of the outputs will only send a logic 1 value when its sensor is picking up more optical light than the threshold limit. When the light level is lower than the threshold limit, the output will instead send a logic 0 value. This style can then be connected to an interrupt within the system board for an ideal usage, although this is not necessary.

^  Table 1: Pin Descriptions  ||
^  Pin Number  ^  Description  |
|  1  |  Sensor S1  |
|  2  |  Sensor S2  |
|  3  |  Sensor S3  |
|  4  |  Sensor S4  |
|  5  |  Ground     |
|  6  |  VCC        |

Any external power applied to the %%Pmod LS1%% needs to be between 2.7V and 5.5V to ensure that no internal components on the Pmod are damaged. Digilent recommends operating this Pmod at 3.3V.
----
===== Physical Dimensions =====
The pins on the pin header are spaced 100 mil apart. The PCB is 1.375 inches long on the sides parallel to the pins on the pin header and 0.8 inches long on the sides perpendicular to the pin header.
----
===== Additional Information =====
The schematics of the %%Pmod LS1%% are available {{reference:pmod:pmodls1:pmodls1_sch.pdf|here}}. Additional information about the other components used within the Pmod such as the op-amp and the inverting Schmitt Trigger are available [[http://www.mouser.com/ds/2/405/lmv324-n-441150.pdf|here]] and [[http://www.onsemi.com/pub/Collateral/NL27WZ14-D.PDF|here]] in their respective datasheets.

Example code demonstrating how to get information from the %%Pmod LS1%%can be found [[pmod:pmodls1:start#example_projects|here]]. 

If you have any questions or comments about the %%Pmod LS1%%, feel free to post them under the appropriate section ("Add-on Boards") of the [[https://forum.digilent.com/|Digilent Forum]].