What about USB support...

[matt_e]

So here's a thought I had - it's 3:30 so forgive me if it's stupid.

Anyway, what about using a microcontroller that has a built-in USB interface? What got me thinking about this is the atmel AT91SAM7S series has built in USB, as well as a bootloader that can download new firmware over the USB connection.

Clearly this chip is pretty serious overkill for our needs, but there are stacks of similar, but simpler chips that'll save a bunch of effort for anyone who doesn't want to buy/build a programmer as well as a bunch of triggers.

The bootloader will also make the whole multiple-personality trigger thing a whole lot easier to deal with, if that's the route we end up going.

Anyway, atmel has a bunch of USB-capable micros over here. There are a bunch of PIC's, and some more from silicon labs.

Anyway, I'm sure you get the picture now...there are tons of cheap micro's out there that support USB natively. We can add that functionality for basically the cost of the connector.

[TwoLeftFeet]

Well, one doesn't need USB to program micros anyway... If we can provide a RS232 interface (RX/TX/GND/POWER) pinouts that can be easily put on a DB9 connector, then you can program the chips that way as well. Either way, we would need to have some software on the PC side that would do (a firmware uploader for either USB or RS232).

[matt_e]

I agree, you don't need USB to program micros, but these days not every computer has a serial port - in fact I don't think I've seen a laptop in the last two years that had one. A USB programmer is considerably more work than an RS-232 programmer, but if the micro supports USB, it's easy.

[seaton]

USB may be better as the connecter is more low profile and may be better suited to an enclosure, while if we use RS232, then we need to get a connector made, as I don't think we would want a DB9 hanging offour super sleek case

I know I usually array around a USB Camera cord with my kit

+1 for usb

[MQ]

+1 for USB.

I have USB on all my machines while COM ports have vanished.

[Thonord]

while if we use RS232, then we need to get a connector made, as I don't think we would want a DB9 hanging offour super sleek case

I think USB is the way to go too, but you don't need a db9 to use RS232.
If you use RS237 (pins 2, 3 and 7), All you need is a stereo jack.

Tom

[Rudeofus]

USB connectivity is cool to have, but there's no reason we must have USB on board at all cost. While few new laptops have RS232 ports anymore, converter dongles from USB to RS232 are cheap and widely available.

If, for whatever reason, we decide we absolutely want USB and none of the micro processors we decide to use support it directly, we can add this functionality any time later (think ft232, ...), either directly on board, or as a little module board.

[seaton]

while if we use RS232, then we need to get a connector made, as I don't think we would want a DB9 hanging offour super sleek case

I think USB is the way to go too, but you don't need a db9 to use RS232.
If you use RS237 (pins 2, 3 and 7), All you need is a stereo jack.

Tom

Agreed, but you do need a custom cable. I carry a USB cable in all my cases, If I lose it then I can get one at just about any computer/Camera shop.

[MQ]

Agreed, but you do need a custom cable. I carry a USB cable
in all my cases, If I lose it then I can get one at just about any
computer/Camera shop.

Second that. The more universal the system is, the more successful
and failsafe it will be.

[Rudeofus]

Agreed, but you do need a custom cable. I carry a USB cable
in all my cases, If I lose it then I can get one at just about any
computer/Camera shop.

Second that. The more universal the system is, the more successful
and failsafe it will be.

It will not necessarily be more universal, because with USB you need dedicated drivers most of the time. Thinks 10 years ahead, most USB chips may no longer be in production, and the then current flavour of windows, osx or solaris may not support it anymore (driver issues under vista anyone ?)

[MQ]

It will not necessarily be more universal, because with USB you
need dedicated drivers most of the time. Thinks 10 years ahead,
most USB chips may no longer be in production, and the then
current flavour of windows, osx or solaris may not support it
anymore (driver issues under vista anyone ?)

Point taken, but for the next 10 years or so I think we
would be on a pretty safe side.

However, I am open to any better suggestion.

[Rudeofus]

Point taken, but for the next 10 years or so I think we would be on a pretty safe side.

Should be, not sure, though. Think of Mustek scanners, for which no Win2k drivers existed. Tons of otherwise useful scanners going to waste

However, I am open to any better suggestion.

Well, there was my idea about routing RS232-signals at TTL level. Then use little module boards for either RS232 level converter (MAX202) or RS232-USB converter (ft232, ...). In this case we can either save money (for folks who have no need for changing the firmware) or maintain maximum flexibility (for future bus protocols, or computers with no USB drivers)