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Analog Joysticks

426 bytes added, 14:12, 4 April 2010
/* Analog PC Joysticks */
== Analog PC Joysticks ==
Analog PC Joysticks have a very similar 15pin connector. TheoreticallyBut with some differences, a few which cause compatibility problems. Statistically, many people reported the analog PC joysticks might be '''do work''' with analog CPC+ compatiblesoftware. However, in practice, this is rather unlikely Many other people reported it won't work - the potentiometers must have correct value, the button common pin must be correct, and the though it's quite possibly that they simply made some fundamental mistakes (like trying to use "digital" 15pin joysticks as "analog" joystick may not contain additional electronics like auto-fire circuits, electrolyte capacitors, or digital-switch to analog-signal convertersthat they didn't even had proper CPC+ software for testing).
* '''CautionButton Common Pin''' - compared with In PCs, the button-common-pin can be at Pin4 or Pin5, on the CPC+/GX4000 do output '''reversed polarity on the joysticks power supply''' pins, so it must be Pin4 (or Pin12 for 3rd-4th button; if any special electronics in '''PC joysticks may get destroyed''' when connecting them to a CPC Plus/GX4000). If necessary, rewire that pins.'''
If you want to use a * '''Reversed Supply Voltages''' - Compared with PC joystick: Remove any electronics other than Gameports, the +5V and GND are connected vice-versa in the CPC+. This is no problem for the potentiometers (both PC and buttonsCPC+ use Pin1 as pot-common). Ensure However, it is a problem if the joystick contains '''additional electronics''' (auto-fire circuits, electrolyte capacitors, circuits inside of ''digital'' joysticks/gamepads that buttons are wired do emulate analog signals, etc.) These won't work (and may get damaged by the reversed voltages). If necessary, remove any such electronics before connected the joystick to correct common pinthe CPC+.
* '''Resistor Values''' - In PCs, the A/D conversion is done by software timings, meaning the PCs could handle joysticks with different potentiometer types (anything from 10 kiloohm to many megaohm should work). The CPC+ does the A/D conversion by hardware, this requires less CPU load, but it also means that it requires fixed potentiometer types (circe '''138K''' ohm).<brp>
Analog PC joysticks are reportedly most commonly using '''100K''', '''120K''', or '''150K''' ohm pots. These types should be more or less compatible with the CPC+ (100K/120K won't reach the ADC=3Fh max value, for example, resolution might be only ADC=00h..30h. 150K would be clipped to ADC=3Fh for anything above 138K ohm.
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To handle those different pot types, CPC+ software should include calibration options. There are also some PC joysticks with incompatible pot types like '''300K''' ohms - these won't work (since values above 138K will be clipped).
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