Originally Posted by glt
I see. Somehow I had the impression that this was intended to be used with another (main) Arduino board.
it depends on how complex the problem is that you are trying to solve. for some things, this single board can hold all the digital control stuff and the other functionality-boards (volume control or input selection, etc) perform their primary function and simply have some management interface (i2c bus, for example) for a cpu to control it over.
in other cases, it might make sense to have a 2nd local processor receive the i2c serial stream and convert commands meant for it into local bit-banging of some other chip or subsystem. I don't see this as the usual case, though, but its possible to do this and still stay inside the overall architecture.
|So if this is intended to be used standalone, why not include the usb device? to facilitate programming? That thing alone costs 10-20 bucks as a separate board.
yes, its a $20 cable if you buy it in easy to use cable form. our interface follows the FTDI 6 pin 'standard' (reset on one end; 2 grounds on the other, vcc and tx/rx in the middle) and so this is one way to break down the 2 functions: 'programming' and 'using'
'using' happens much much more often than programming. I think it makes sense to optimize for the typical use case. I could forsee many installers that may be ok with 'off the shelf' applications pre-programmed in the chip and they simply install it and use it. in that case, they never need any host or computer/pc interface. why make them pay for things they don't need or want?
for those that want to edit or change their apps, they can buy the 'download cable' and you buy that once, no matter how many devices you build that use arduino. once you 'flash' them with software that gets sent over that fancy cable, the code stays inside and if you're happy with the code, there's no reason to ever connect that port to a pc again.
some people may want to have a 'ready to use' usb port on the back of their amps and systems. in that case, you can buy a small board that does what the magic cable does:Arduino miniUSB: USB to TTL converter (FTDI) [v3] - $20.00 : Adafruit Industries, Unique & fun DIY electronics and kits
Arduino "miniUSB": USB to TTL converter (FTDI)
or one like it.
mount that in the rear panel of the amp or dac (note, this is NOT a usb/spdif port, its a 'management port' and talks TO the box, not THRU the box; if you get what I'm saying).
that becomes your management port for when you need to update the box's firmware.
that little usb board just needs those 6 wires sent up front to the lcd area and you're done.
|Also, I like 4x20 LCDs because I can't see the little numbers at a distance and with a 4 line LCD I can display numbers that are much larger (9X larger)
4x20 uses the same pinout as the 2x16 ones do. the only tricky part is that the mounting holes from the lcd to the daughter board (the LCDuino) won't line up. but its not the end of the world (that's not due for at least a few more years, lol) - the larger 4x20 lcd can mount onto the front panel on its own 4 screw holes and the backpack can 'hang' onto the lcd via the top 2 6pin header strips. there's actually a good amount of hold power in all those pins and header sockets. that may be enough for many people. the lcd mounting to the front bezel is the hard part; but the backpack module isn't in need of the same level of fastening.
its also possible that another board, the same size as the 4x20, could be made using the same general idea as the LCDuino-1. maybe its the -2 version
think of all the extra proto hole room in THAT one
the nice thing about the 2x16 size is that its a good balance of 'real estate' on the lcd and small physical size. it can fit in a 1U rackmount and given that used pro audio boxes can sometimes be found cheaply, its nice to be able to come in under the 1U height.
I've also used double sided foam tape to secure the 'dangling end' of a smaller backpack to the back of a larger display. the top pins holding it and the foam tape were enough for me. ymmv, of course.