English Amiga Board - View Single Post - Default analog joystick specs, improved support?

Daedalus · 08 January 2020, 22:58

What are you reading those values in? A joystick tester? The values should have a much larger deflection - in theory the pot values can range from 0 to 255, though you would be best keeping away from the upper limit in case you manage to go slightly past it and wrap around to 0... Not good in a tense flight sim moment! You don't want to have the value too low either as that reduces the resolution of the movement.

I'm sure most games of the era must have had some sort of calibration system, because analogue controllers of the time didn't really do defined values as the pots weren't used as potential dividers and so the upper limit of each axis (and therefore the centre point of each axis too) is rather arbitrary.

Additionally, the Amiga has slightly different specs for pots than a PC analogue input uses. On the Amiga, the pot should be 470K linear to give readings reasonably close to full-scale, but PC joysticks tended to use much lower values, between 100-200K typically, which will give much lower deflections on the Amiga, naturally. If I were to guess, and the value you're getting of 30 is an actual pot counter result, I'd say your stick has 100K pots in it.

Back in the day, I was a big fan of my analogue stick and fitted my towered A1200 with a 15-pin port especially for them, but had a similar problem with very low readings. I managed to improve the sensitivity and full scale deflection of the stick by adding small capacitors across the pot inputs. This had the effect of increasing the range from the pot registers, thus increasing the smoothness of the analogue control in Birds of Prey and F1GP (the two main games I used it for). If you're handy with a soldering iron, it could be worth experimenting with some small capacitors (try the 50-200nF range - from memory I used 100nF capacitors) added to your adaptor.

08 January 2020, 22:58	#3
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,351	What are you reading those values in? A joystick tester? The values should have a much larger deflection - in theory the pot values can range from 0 to 255, though you would be best keeping away from the upper limit in case you manage to go slightly past it and wrap around to 0... Not good in a tense flight sim moment! You don't want to have the value too low either as that reduces the resolution of the movement. I'm sure most games of the era must have had some sort of calibration system, because analogue controllers of the time didn't really do defined values as the pots weren't used as potential dividers and so the upper limit of each axis (and therefore the centre point of each axis too) is rather arbitrary. Additionally, the Amiga has slightly different specs for pots than a PC analogue input uses. On the Amiga, the pot should be 470K linear to give readings reasonably close to full-scale, but PC joysticks tended to use much lower values, between 100-200K typically, which will give much lower deflections on the Amiga, naturally. If I were to guess, and the value you're getting of 30 is an actual pot counter result, I'd say your stick has 100K pots in it. Back in the day, I was a big fan of my analogue stick and fitted my towered A1200 with a 15-pin port especially for them, but had a similar problem with very low readings. I managed to improve the sensitivity and full scale deflection of the stick by adding small capacitors across the pot inputs. This had the effect of increasing the range from the pot registers, thus increasing the smoothness of the analogue control in Birds of Prey and F1GP (the two main games I used it for). If you're handy with a soldering iron, it could be worth experimenting with some small capacitors (try the 50-200nF range - from memory I used 100nF capacitors) added to your adaptor.