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| Can we connect happ P360 with regular 4/8 joystick??? |
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| MonMotha:
Will it work if you just wire them together? Yeah. Is it a good idea? Not necessarily. Eventually, you'll burn up the high-side driver on the P360. This isn't a big deal really, since the only application you'll ever hook it up to has a strong pull-up, but it's not exactly good, either. Occasionally, the low-sides go out too, and then you'll have a non-functional stick. Also, somewhat excessive currents will be drawn whenever the regular stick has a switch closed, which could overload some small supplies (like that from an unpowered USB hub), depending on how strong the high-side drivers of the P360 are. I usually just chuck a low-Vf diode in the line with the push-pull output so that it can only pull low, but not drive high, the input. You can also use a simple resistor to limit the current, but proper choice depends on the pull-up used on the game board. You can also use an open-collector/open-drain buffer, or an inverter and some transistors for an even more "proper" solution. |
| superbigjay:
--- Quote from: MonMotha on April 24, 2007, 05:12:18 pm ---Is it a good idea? Not necessarily. Eventually, you'll burn up the high-side driver on the P360 ... I usually just chuck a low-Vf diode in the line with the push-pull output so that it can only pull low. --- End quote --- Thanks, burning the p360 drivers was my concern. So if I go the diode route, I could use 4 diode per P360 like this: |
| MonMotha:
That usually works fine. 1N4148 type are OK, but low Vf shottky types work better for CMOS inputs as uber-low reverse leakage isn't a major concern. Most uC inputs (like you'd find on PICs, most 8051s, AVRs, and other uCs used on keyboard encoders) have TTL thresholds, so the higher on voltage of a 4148 (especially at the mA level currents flowing) is acceptable. I wouldn't expect any problems with that setup, and you won't have to worry about burning up the high-sides or excessive current consumption. |
| superbigjay:
thanks MonMotha for the quick replies... Do you have a part number or spec for a low vf shottky diode that I could find at the electronic store on online? thanks |
| MonMotha:
It's not likely to matter (give it a shot with the 1N4148s - if it doesn't work, I'll be surprised), but I'm a fan of the BAT54H. It's not available in a leaded package, though, only surface mount. I can't think of any off-hand that are available in the more conventional leaded packages. |
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