Linking software  

ASM archive  


IR Link  


PIC16x84 programmer  

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The Circuit:  

IR Link Circuit  

Notes on the schematics:  

  • The resonator can be replaced by an xtal with two 15pF to 33pF capacitorss.
  • The circuit can be powered from a 9V battery, since there is a +5V voltage regulator. It can be also powered from a 4.5V flat battery. A 4.5V battery has a long life and is cheap, but a 9V one is more portable. Personally I prefer 4.5V batteries.
  • A PIC16C84 of a PIC16F84 can be used. However a PIC16F84 is better and cheaper. When programming a PIC16F84, make sure you set the fuses to: XT, WTD_ON and PWR_ON. You can also have Pre-Programmed PICs from me.
  • Don't forget to download the LITE code for the PIC from the Software downloads section.
  • In the LITE version there is only 1 switch on RB7. The other switch is only useful in the STANDART version.
  • R10 and R11 are new. They are pull-up resistor that are needed on some calcs(some old calc versions does have them built-in) and are also needed if the cable is long. On some calc like the TI8x a value of 47k is enough. For the TI89 and TI92 22k are ok.
  • There was a previous schematic that used a 78L05 regulator. You can find it here . But the 2931Z5 regulator is better
  • than the 78L05 because it takes less power and gives more protection.



    The values of the components:  
  • R1: 330 Ohm
  • R4,R6: 80 kOhm  (or anything near)
  • R3,R5: 620 kOhm (or anything near)
  • R8: 470 Ohm
  • R9: 120 Ohm, this one depends on the IR LED.
  • R10,R11: 22k Ohm.
  • C1: 4.7 uF. Tantalum electrolyte is prefered.
  • C2: 100 uF if normal. If tantalum are used then 22uF is enough.
  • C3: .1 uF. Tantalum electrolyte is prefered.
  • Resonator: 4MHz
  • D1: IR LED, see text.
  • D2, D3: 1N4148
  • D4: Any RED LED.
  • SFH506: IR Reciever: SFH506-30



    The IR reciever module:  

    The essential part is the SFH506-30 from Siemens. This one operates at 30khz.  
    It may be hard to find Siemens parts in the US. Here  
    is a link to Siemens distributor in the US:  

    This module is compatible with SFH505A also from Siemens (this one isn't more produced). Take a look at the Datasheet of the SFH506 to see the pins description.  

    I am also providing this receiver. Check the  Pre-Programmed PICs page.  

    The IR LED:  
    Any IR LED that has a wavelength of 950 nm can be used instead of the SFH415 from Siemens. In the Datasheet of the SFH506-30 they say that with the SFH415 a range up to 34 m can be obtained.  

    Extending the range:  
    To extend the range, multiple IR LEDs can be connected in parallel, the same way as D1 is connected. Like this:  


    To reset the PIC you have to unplug it from the calc and from the power, or you can add a simple push button this way:  

    Reset circuit  

    Using a PCB:  

    Currently here are only 2 PCBs design. One by me and another by Thomas Koglbauer . I 
    have also a PCB design that I will release later. 

    I have designed this PCB for the IR Link. Some notes to it:  

    • There is place for 2 IR LEDs and their 2 resistors. You can use only one IR LED.
    • There are 3 connectors:
      • To the calc: With 3 pins.
      • To the battery: 2 pins.
      • To extra hardware: 6 pins: 4 for the I/O expansion and 2 for power.
    • Before printing the PCB you have to scale and mirror the image!
    I have tested it and it is working. There was a tiny error in the old PCB that was on this page.  
    If you have built it, here is how to fix the error: pcbfix.htm  

    The PCB:  


    The Tracks and components:  

    Tracks and components

    The components description:  

    Components description

    Second PCB design: 

    Thomas Koglbauer sent me this PCB desig, which is smaller than the one above: 

    The parts placement: 

    Using a strips-board:  

    A strips-board can be used to make it easier to build the link. All you have to do is to cut some strips and to solder the components. Antoine Mercier has proposed the placement of the component.  Thomas Koglbauer  sent me a correction and an unpdate of it. On the image you have :  

    • The tracks are in orange.
    • The breaks are in blue. Here you have to cut the strip.
    • The places of the components are in black. You have to solder them.
    • The green round is where you have to solder the cables.
    • The gray connections are the wires or metals that connects two strips.
    • The 0V isn't shown here. It will be added soon.
    See the first photo of my circuit to get an image on how it will be done.  
    The places of the components:  
    Components places

    The front view:  

    Front View  

    Back to index.  
    Author : Sami Khawam