VK3ZPF ROTOR HUNTER
PARALLEL PORT INTERFACE

'ROTOR HUNTER' uses a modified Dick Smith Electronics parallel port interface kit (Cat K2805).
The interface can monitor ten analog voltages, drive eight digital outputs and generate two variable voltages.
For the 'ROTOR HUNTER' (V1.09) I make use of five analog inputs. Future plans include automatic control of input attenuators which will make use of the digital outputs feature.

'ROTOR HUNTER' (V1.09) uses the analog inputs as follows
  • INPUT Ø - input from the position indicating resistor.
  • INPUT 1 - input from VHF receiver signal strength
  • INPUT 2 - input from UHF receiver signal strength
  • INPUT 8 - digital input from index sensor
  • INPUT 9 - monitors the voltage sent to the position indicating resistor.


picture of parallel interface

KIT MODIFICATIONS

MAKE IT RIGHT - MAKE IT WORK - FIRST

As with most modifications it is good to know that it worked BEFORE the modifications were done. To assist your success I suggest you build the kit, following the provided instructions and check for correct operation of all functions first. After checking all is well the following changes are required to enable the parallel port interface to work with the ROTOR HUNTER software and hardware.

  1. Jumpers J1, J2, J3, J4, J5 and J6 are positioned between 1 and 2 as shown on board.

  2. Remove Q2. It was found early on that Q2 may cause a voltage supply problem and so it was removed. A link must be placed from where the emitter of Q2 was to where the collector of Q2 was.

  3. In order to provide a digital input for the index indication a wire is run from pin 10 of SK5 (input 8) to pin 11 of SK6 (25 pin D connector).

  4. A +5 volt supply is required for the position indicating resistor and this is provided through pin 11 of SK5 (input 9). A wire is taken from pin 11 of SK5 to a convienient +5 volt supply point such as pin16 of IC2 (74HC595).

  5. The infrared L.E.D. used for index detection is powered through a 330 ohm 1/2 watt resistor connected between pin 12 of SK5 (unused) and pin 8 of IC6 (LM358).
For more info on the ADC, parallel ports and some software visit:

http://www.ti.com/sc/docs/products/analog/tlc542.html Texas Instruments - TLC542 ADC

http://www.beyondlogic.org/spp/parallel.htm Interfacing the Standard Parallel Port

http://home.rmi.net/~hisys/parport.html IBM Parallel Port FAQ/Tutorial

http://www.lvr.com/parport.htm Parallel Port Central

http://www.siliconchip.com.au/HTML/SOFTw.htm Silicon Chip magazine - Software download


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Copyright 2000 - Peter Fraser - all rights reserved.