Some projects need a control panel, but are in situations which make that cumbersome. Unlike bench equipment, which would be useless without built-in readouts, other control devices could use interfacing just to alter a few settings or take occasional readings. This device’s first job will be interfacing to my hydroponic controler.
This unit provide 2 way IR communications using a numeric keypad and an LCD display. Data is sent and recieved in ASCII with no regard to what the data means to any particular device.
The ASCII data still needs some form of encoding. For this I chose [url=http://mondo-technology.com/tricks.html]10-pulse coding[/url] of 38Khz IR using a nifty 99 cent receiver chip , TSOP4838 The transmitting is done with a straight IR LED with both carrier and coding done in software.
As you can see from the diagram below, the membrane switch and LCD display use up quite a few I/O lines even with some sharing of signals. This required the use of a larger (28pin) PIC for this controller. However, it means that the target device it controls needs only 2 I/O lines for sending and receiving the IR data. Although functional at this time, some features and nicities need to be added later.
Here is the current state of the [url=http://www.circuitdb.com/download.php?fileID=182]Source file[/url].
Copyright 2006 [url=http://mondo-technology.com/]Luhan Monat[/url]Parts:IR LED and receiver:
TSAL-6200 Vishay IR LED 940nm
TSOP-4838 Vishay IR Reciever 940nm 38khz