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| From the engineer | |
This Q&A should answer most questions about the pictures. Technical information in this Q&A is about the *prototype PD-02 4.0B mainboard only*. We don't have a prototype case, input panel or anything else at this stage. Last update: 25/03/2002. 01. Why is it REV 4.x? Shouldn't it be REV
1.x or REV 0.x if this is the first prototype?
A: Since this project started many moons ago, the design (both electrically and functionally) has changed over time quite a bit. We have a REV 2 board but it was never populated. All other revisions (there are many) only exist on computer and the revision numbers are simply a way of version tracking schematics/PCBs that we have accumulated. This board you see here is part of the PROTOTYPE "series"; obviously for the first PRODUCTION run the version will be reset to 1.x.. Q: 02. What's with the corrosion/mess around some of the joints on the top? A: It's a long story. It involves carelessness, an open bottle of metho, and a nasty chemical reaction with the solder flux/PCB lacquer/metho. Luckily the bottom layer was the worst affected and the easiest to fix; it has been cleaned up and re-lacquered. The top has been touched up by hand (some joints have been re-worked).
A: Prior to taking these photos, the board was being tested (power supply load/regulation/distribution, signal continuity, shorts etc.) before any ICs were installed. There may be more photos in the future when the whole thing is mostly operational. Q: 04. Why are the power filter capacitors so close to what appears to be the 5v regulator/heatsink? Won't that reduce reliability? A: That's true. There was a bit of a layout issue that I couldn't justify spending more time on, to resolve for this prototype. Rest assured the filter caps will be further away from the hot bits for the next prototype/production boards. Q: 05. Isn't that switch/rectifier bridge overkill? A: Yes. When parts supply has been sorted for production, the final product will be more cost effective. For now, it's just an issue of what's available.
A: Expensive: No, not for small runs/prototyping. Low tech: Yes. But this is a prototype. Notice I also had to /hand solder/ each of the 300 vias on this board. In an ideal world, the production version would be surface mount all the way (except plugs/sockets), which would reduce the depth of the board significantly (especially without the test headers/jumpers). In the end, it's the economics of scale. To justify a fully SMD board populated by p&p robots we would need serious money/make hundreds of units at a time... Q: 07. Why all the jumpers? A: The vast majority of jumpers (99 of them) isolate each microcontroller's I/O pins individually. There's also isolation jumpers for the USB FIFO and ICSP/POWER on each MCU. Other jumpers configure USB reset circuitry, MIDI TX/RX, and analogue sampling voltages. Basically, these jumpers allow easy development of the firmware by enabling us to isolate various things from each other (or even re-route signals in a different way to the PCB pattern).
A: We are considering providing an RS232 option that could be installed by us or sold as a kit. We may even sell a small number of PD-02s with RS232 as standard. Why is this necessary? Because this unit is potentially useful for applications other than MIDI, RS232 is most certainly required. RS232 has been an industray standard serial interface method for many years, and is in use in many industry installations to this day. It may also be useful for firmware development if for some reason the developer cannot use USB. Q: 9. Why the reset switch? A: Firmware development. The final version obviously will not need resetting whilst in use. However, due to our decision to open source the main MCU's code for end user development, we will probably leave the reset switch in there (though it may be moved to a different location on the PCB).
A: We haven't decided what GPL license to use yet. However, we have concluded that it would be useful to provide the firmware source (in commented ASM), along with sufficient hardware documentation and software tools, so that the end user can develop their own software for our unit. Since we have one MCU dedicated to (amongst other things) reflashing the main MCU via USB/RS232, there is no danger in corrupting or erasing the main firmware so that the whole device becomes unusable. So, apart from the lack of in-circuit emulation/debugging, developing firmware for our device should be a breeze. This also allows the possiblity of online firmware updates: although we will endeavour to make sure this doesn't have to happen, you can be content in the knowledge that we will be able to provide updates for your controller after you have purchased it, depending on your feedback. Don't like the way a certain feature works? We can fix it. Noticed an obscure quirk during normal operation? We can fix it. We may even open up a sourceforge.org entry so that online contributors can release/share code and flash updates.
A: Wait until some time in April (at time of writing it's late March) when we should have most of the planned features working. That way, we wont' become an (in)famous vapour-ware company that fails to deliver promises. All the hardware is designed, and most of it has been constructed: apart from the (mostly) complete mainboard, we have two out of three test jig boards that are necessary to emulate the "input panel"; the final one will be made once "serious" firmware development/testing commences. That said, this is a list of the current *capabilities of the mainboard* (not final) (subject to change!): . 128 digital buttons Q: 12. I have suggestions/feedback/want to help in some way with development or production. A: Please visit the Analogik forums Q: 13. I want a release date! A: Sorry, we don't have a crystal ball :-) |
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Q:
01. Why is it REV 4.x? Shouldn't it be REV 1.x or REV 0.x if
this is the first prototype? 
Q:
03. Why aren't any of the ICs installed into their sockets?
Q:
06. Isn't through-hole technology expensive/low-tech? 
Q:
8. What's this about RS232 serial expansion? 
Q:
10. What's this about opening up the firmware source with a
GPL license? 
Q:
11. I want exact specs/complete feature list! Copyright Communication 1 to 1
Pty Ltd, Dejan Petrovic and Paul Harvey (C) 2001 - 2002 |