My home built metal DDR pad (Part IV)

[marcan]

I've modified the circuit to be a controlled amplifier and output a signal that could be useful for a PIC ADC. It still uses only two opamps. This time, one amplifies, and the other buffers the reference voltage (since I need a constant voltage source to use proper gain control, and a pair of resistors alone isn't a constant voltage source)



First you set gain to max (R1 all the way towards the opamp) and adjust R6 so that the output just cycles or is in between. Then decrease the gain to a controllable level (R1 a bit to the other side, you'll probably need a multiturn pot or maybe decrease its value or increase R7, I haven't tried) and watch as the output smoothly varies according to the pressure applied. Might need a bit of experimentation or reversal of the gauge connections, but it works quite well for me and it is quite simple to build. Oh, don't touch the connections while adjusting, since the power and voltage levels are quite sensitive. No precision resistors needed anyway, although it might help if they are more thermally stable (haven't tried).

[marcan]

I've been looking at the PSX pad specs and the 250khz clock speed seems quite a lot to handle efficiently using software. BUT, the SPI controller on the PIC16F873A (and others) seems just perfect for the task. The bit order is inverted, but that doesn't really matter (we just handle the data the opposite way), and it does everything using on-board hardware. Schweet!

It all fits in nicely with the PIC pinout and the PSX pad pinout:

ATT = /SS
CMD = SDI
DATA = SDO

CLK = SCK

and ACK we can handle manually. Actually ATT lasts for the whole transfer and /SS works for just one byte, but we can use the command value (and maybe a pullup) to detect restarted transmissions.

EDIT: we might have to scratch off /SS and handle that manually, since the pin will be set to analog (there's no way around that while still having 4 A/D pins free).

My idea for pinout:

RA0,RA1,RA2,RA5 - analog inputs
RA3 - adjustable vref
RA4 - ACK

RC0 - SELECT / /\ / something
RC1 - START / O / something
RC2 - LEDEN
RC3 - CLK
RC4 - CMD
RC5 - DATA
RC6 - LED0
RC7 - LED1

RB0 - ATT
RB1 - BSEL
RB2 - BINC
RB3 - BDEC
RB4 - RB7 - digital outputs (for lamps etc)

where LED0 and LED1 and LEDEN would be wired to a 74HC238 chip or similar to drive 4 LEDs (either all off or one of them on) to use as "calibration select", and with a button wired to BSEL you choose what button to calibrate. BINC and BDEC to increase or decrease calibration threshold. We could make these another 2 button inputs when no sensor is being calibrated.

[MyDancePad]

If you have not had time to look at mine. There are no moving parts or switches :-) straight old fasion contact. just like the pressure switch. the plexiglass itself is what completes the circut. Its held up for over a year of HEAVY pounding (and btw for those of you wanting a good exercise, im loosing about 2 - 4lbs a week on standard, 1.5hr workout in the morning before you eat)


take a look

kind regards
Riki
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visit my site for an indepth tutorial on building your own arcade style dance pad
My Dance Pad
riki

[marcan]

[MyDancePad]

Yeah, I realised that after I sent that. There is a different between a "pressure" switch, and a "contact" switch. Now what would be really inovative, is a way to make a controller without having to rely on ripping existing ones apart. You guys look like you know a lot about electronics. What is your take on that? Is it possible? How complex would that be?
_________________

visit my site for an indepth tutorial on building your own arcade style dance pad
My Dance Pad
riki

[tolookah]

both of us seem to be working on projects really close to eachother (same hardware just about) but I am hoping to make mine xbox compatable

Yes, it is possible, Complex? PSX not much, Xbox yes. (though mine will also include lighting drivers and a default mode just to show off the lights)
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Aim: Tolookah
MSN: Tolookah
XBox: Tolookah
DDRPad Soldering and electrical Help: http://www.tolookah.net/DDR/ As hooded_paladin put it: "Currently, help for Beatpad Pro, official Sony Playstation Controller and ANY controller unless you are extremely stupid or lazy."

[marcan]

Our projects attempt to reinvent the whole interface part, not relying on ripping apart other controllers. Mine will have a PSX pad interface, which could also plug in to the PC via a PSX->PC parallel or USB adaptor. It is not very complex, since the PSX protocol is just a kind of synchronous serial slave with a couple added stuff. It would also be very simple to modify to build a simple pad emulator with the microcontroller, ignoring the pressure stuff and just focusing on straight digital inputs, which could be very useful for people building their own contact-style pads. You could emulate just about the whole PSX pad with a PIC, all 16 buttons (no analog though, you'd need to remove a couple digital buttons to add analog inputs, but anyway, analog inputs are not much use for DDR pads, and if anyone wants to use it for something else they can probably spare a couple digital buttons. Or use a microcontroller with more pins)

Few parts would be needed. Ignoring the whole pressure stuff of my pad, the general circuit for the microcontroller would just need the mcu itself (not very expensive, <$10), and an oscillator (quartz crystal, or resonator which is cheaper, or just an R-C oscillator which costs about two cents. The latter is terribly inaccurate, but since the communication is slave it doesn't matter), plus a stable supply and a couple of resistors and capacitors (if no stable supply is available, a simple power supply takes two capacitors, a 7805 regulator, and any wall wart, and a rectifier if the input is to be AC)

For lighting you could just grab 4 mosfets (power mosfets if you're going to use light bulbs, or just about any decent transistor for one or two LEDs), plus the circuit needed to drive them (at these extremely slow speeds with no PWM, a signal transistor and a couple of resistors is fine). Or use relays, which are very low-tech but easier to handle (and can handle very high loads)

[Ulala321]

[deM']

ulala, why dont you go get the metal and try it, all soldering irons heat up differently, but an average 20-30 watt iron should be fine

[stupidbarber]

[NaraShikamaru]

Since nobody answered my question after several days I'll post again .

I've looked at several different metal dancepad guides what I would like to know is which dance pad is relatively the sturdiest (I weigh 240 pounds), the
and would like to know which pad(s) will last...


A second question (but less important) in your experiences which designs cost less (supplies only, not tools)?

Thank You!

[Enterprize]

Hey! I read up to page 63 and a few back from here, but figured the best way to get up-to-date and precise results was just to ask my questions here.

My friend and I are planning on building one or two homebuilt pads. We're planning to follow Riptide's design.

Just a few questions.
1) What is the best controller to use as far as longevity? Is there any controller that more or less lasts indefinately?
2) What is the best contact design? (Wouldnt the screws be the contact point with the mending bracket design, defeating the point?)
3) What's the best rebound material?
4) Is 1/8" acceptable for the lexan dimension?
5) Is there any way to prevent the wood stripping with repeated unscrewing? My friend has 2 fluxes and filling the holes has never really worked well for him, the screws always tend to come loose quickly.

Thank you very much! Help is muchly appreciated!

[Heffenfeffer]

[MyDancePad]

[Enterprize]

Thank you for the quick responses! I was afraid I'd have to wait pages for my questions to be addressed *whew*

1.Great. Finding a softpad PCB shouldnt be too much trouble.

2. Really? I would think getting them all level would be fairly simple, as long as you used a single type of washer.

3. Would leaving an inch in the middle of each side for air to escape be the recommended course of action with weatherstripping? Also what about the vinyl tubing people have been using? Has anyone who used it had any great success with it? How would you go about using it?

4. So, 1/4" Lexan would work? Wouldnt it be a little too big? (riptide calls for .22")

5. Alright, that should be good then (My friend LOVES his fluxes when screws fall out in the middle of a song)

[NaraShikamaru]

Thank you both! If anyone else has feedback It'd be appreciated

[Heffenfeffer]

[Aflac]

How do you all keep your homepads clean? I've danced on mine for about a week now, and I've noticed some oddities. First, the aluminum flashing is getting scratched and dented, making the pad look quite shoddy. Second of all, I've noticed little marks underneath my lucite panels. I'm not quite sure how they got there, but I think they have something to do with the graphic? Who knows.

Anyway, no one ever answered this question - I have a small crack in the bottom right screw of my top arrow. The crack developed the second time I played on it, but has yet to get worse. Its cracked on the underside of the top sheet of lucite, so its not quite exposed. What should I do? Is there an easy way to fix lucite cracks?

Note: my lucite is advertised as 20x stronger than glass, and the crack is about 1 1/2 centimeters long.

[deM']

20X stronger than glass is actually very weak for plex, considering lexan is 200X... Just think about it, if you put a slab of glass under the panel, how long would it take you to break it?

And no, to my knowledge there is no way to fix plexi cracks, just buy a new peice, 4 bucks...

[Raiv Xomby]

I looked through the thread, but there are 231 pages and I can't find anything about it.

Does anybody have a link to an Xbox controller soldering instructions? Or should I just make a playstation style controller and get one of those little units to plug into Xbox?

How much do those cost anyways?
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I shot the sheriff (but I did not shoot the deputy)