Monday, 2 November 2009

PcRc, the 1st car rolls out, maybe not out, but still rolling

Ok, so a while ago I was talking to customer in my work place about wanting to control relays and other hardware over remote desktop or a client - server application. He told me I could use the parallel port to control hardware...

Since then I've done a lot of Googling and Youtubing and found out almost everything I needed to know.

The end goal is to build a fully functioning Red Dwarf Scutter style robot that I can send it around the home, maybe get a beer from the fridge, ok so maybe that's asking a bit much, maybe.

I have found a few good and most importantly free parallel port control programs these are my two favourites...

Jaspreet's port control


JB's RC Controller

Jaspreet's Pro's and Con's


  1. well laid out
  2. access to control pins
  3. displays satus pin state
  4. allows you to create and run loops
  5. run counter option
  6. E-mail Me option

  1. no keyboard shortcut/hot keys for pin control
  2. no ability to save loop and run later
  3. no way of making use of the status pin data
JB's RC Pro's and Con's

  1. very well made
  2. easy to understand
  3. up, down, left and right hot key access to 1st four pins
  4. W, S, A and D hot key access to 1st four pins
  5. change port address option
  6. auto drive screen, random motion or run sequence
  7. VB source code of a stripped down version made available
  1. access to only the 1st 4 pins
  2. sequence.txt was in a .cab file so I was unable to edit (this could have been my setup)
  3. no ability to select any .txt file from anywhere on the computer

Each program has great power for its intended use but neither one is able to do exactly what I will eventually need from such a program so, With the RC Control source code from as my jumping off point I have started to teach myself VB from free tutorials available online.

My 1st program is moving a little slowly but very surely,
It uses keys F1 - F8 to turn on pins D0 - D7
and keys 1 -8 to turn them off again,
I have also included the W, S, A, and D and the up, down, left and right hot keys from the original program.

Djdavies83's parallel port control V1.2

Djdavies83's port control v1.2 Pro's and Con's

  1. Very simple operation
  2. Hot key access to all 8 data pins
  3. Sent data displayed next to pin status indicators
  4. Space bar reset all pins hot key
  1. No port address change option
  2. No control pins control
  3. No loop or sequence function

After watching all of Jaspreet Kaleka's videos I was going to try and use relays to connect the contacts on the remote for a white Toyota Celica, Knowing the ULN2803A gave out a negative I tried to connect directly to the contacts without relays.
At this point it did not work (I was using separate batteries for the ULN2803A and the remote, I did not connect the negative wires together either).

I decided to follow the
"How to Build a PC Controlled RC Car
" on I set about converting the controller of a mini cooper s I was given a couple of years back.

Given the remote was Negative switching this made it quite simple, I first tried the 2N3904 NPN transistors from the guide but these did not work for me, I think as my remote was 9V not 3V like the one in the guide I would have needed resistors between parallel port and the transistors.

This mess was the first parallel port control project I made, It used a ULN2803A darlington
transistor array to send power to
the relays that drive the motors. knowing that the ULN2803A could happily send power to relays when it was told to by the parallel port I tried it on the remote for the car and it worked a charm (when it was powered from the same battery as the remote), it was also very simple to fit with allot less soldering than 4 transistors.

Here is a pictorial wiring diagram for using the ULN2803A with a car remote.

Just as the car can be remote controlled from the pc, the pc can be remotely controlled by another pc, this can be fun when your in work for example...

My next post will include a link to the fully compiled 1.2 version of my port control program and a step by step guide to building your own PcRc Car.

Till then have fun and stay safe, Peace.