Date   : Sat, 21 Jun 1997 13:16:52 +0200
From   : "Mark Usher" <marku@...>
Subject: Joysticks / Analogue port

Hi... ouch just burnt my finger again with the soldering iron :-)

OK then.  Who can help me with this piece of what should be fairly basic
electronics.

What I am trying to do is use a PC Joystick / Gamepad on a BBC, and I'm
getting a little stuck.
Here are the appropriate pins etc.

PC     Description     
1      +5V DC  
2      /B1 Button 1    
3      X1 Joystick 1 - X       
4      GND     
5      GND     
6      Y1 Joystick 1 – Y       
7      /B2 Button 2    
8      +5V DC  
9      +5V DC  
10     /B4 Button 4    
11     X2 Joystick 2 – X       
12     GND     
13     Y2 Joystick 2 – Y       
14     /B3 Button 3    
15     +5V DC  

and on the BBC

1      +5v     
2      0v      
3      0v      
4      CH3     
5      Analogue Ground 
6      0v      
7      CH1     
8      Analogue Ground 
9      Light pen strobe        
10     Digital Switch Input (I1)       
11     Voltage reference       
12     CH2     
13     Digital Switch Input(I0)        
14     Voltage Reference       
15     CH0     

Now I've done the easy bit, ie the fire buttons work.
That is as follows.
PC 2 - BBC 13
PC 7 - BBC 10
PC 4 - BBC 2
and that works quite nicely.

I worked out that the Voltage Reference on the BBC gives the +1.8V that I
should use and along with the analogue ground and the Joystick on the PC I
should get some sort of movement, or at least when it is connected I should
be getting 0.9v which I'm not.

Can someone tell me where I'm going wrong ?

Mark Usher
marku@...
http://members.magnet.at/users/marku 



Mark Usher
marku@...
http://members.magnet.at/users/marku