(12 Dec 02003) - Been thinking a lot about this past couple days. Scanned schematics online soon. The key part is the Delcom Engineering USB interface chip. I've ordered parts from Jameco, and boughts miscellaneous supplies from Al Lasher's Electronics in Berkeley. BTW, I can't say enough good things about their store, and if they would have had more logic ICs, I wouldn't have had to order from Jameco at all. Delcom's USB-B ports are over-priced at $3; Jameco has them for a third of the price, so caveat emptor.
USB-B port pin out (and some other ports too; pretty useful)
My Jameco order is waiting at the post office, so my plan for tonight is to fiddle around with the USB IC (which I just picked up from the post office this morning), and get a feel for it. IC data sheet.
After a night of fiddling, I couldn't get my computer to recognize the USB IC. Voltages look correct everywhere I measure them, but it doesn't show up in IORegistryExplorer.app, and none of my little test programs (or Steve Zellers) seem to be able to find the board. Any suggestions?
Some other pretty cool USB interfaces (and small too)
(13 Dec 02003) - Data sheet for the 74HC164 8-bit shift-register
Built the "candle" (as opposed to shamas) circuitry (independent of USB). Works properly, with pictures in the gallery of me loading and unloading a bit string. If you look at the movie, you'll see that I skip a little bit; this is because I was using a sliding DPDT switch , so the transition isn't perfectly clean. I can also clock them independently for special effects, but I didn't wire it up that way just now (but it will be in the final circuit.
Managed to get the Delcom board running!
Take a look, however the
usb_menorah software throws bus errors when
I tried to run in morse mode. Pin ordering is a little weird to map to bits:
bit => pin control
2^0 = P1.0 ;
2^1 = P1.2 ;
2^2 = P1.1 ;
2^3 = P1.3;
(15 Dec 02003) - Table of expenses
| Item | Quantity | Price (each) | Supplier |
| USB I/O 20-pin dip package | 1 | $8.00 | Delcom |
| Discrete components for USB IC | 1 | #3.60 | Delcom |
| USB B Receptacle | 1 | $3.75 (or $0.89) | Delcom (or Jameco) |
| 74HC164 shift register | 2 | $0.39 | Jameco |
| Red/Green LEDS | 9 | $0.51 | Al Lasher's |
| 680 Ohm (1/4 W) Resistors | 18 | $0.10 | Al Lasher's, stash |
| 820 Ohm (1/4W) Resistors | 2 | $0.10 | stash |
| PNP transistors (2N3906) | 2 | $0.18 | Radio Shack |
| Breadboard, hookup wire | stash |
It works, it works!
What I really would like is a bread-boardable USB socket. The ones I have would fit great into a cutom-made PCB, but the leads are too close together and two short to be useful in a breadboard. OK, so the world market for this is probably small, but still...
Some photos brigther and darker light. The date is simulated.
(17 Dec 02003) - I realized this morning that fancier animations would run more smoothly if I could turn off all the lights (independent of the state of the shift register) while loading the pattern. This could be done by throwing in a PNP transistor between the LEDs and ground (shared by all the LEDs). It would only require one more I/O pin, but I wouldn't be able to use Steve Zeller's simple output API if I needed to use the low-current pins. Maybe for next year.
Schematics are online ( 1, 2).
As far as the final case, I would like to (a) make a PCB (which I don't know how to do yet, but I'll try to find layout software and then send it out), as well as make a clear resin casting around all the parts. This is my concept--I'm going to try to have Santiago (resin-master of the Glowing Hands project) do it for me one of these days, once his studio is operational again.
