[Opendispense] UI design

Matt Johnston matt@ucc.asn.au
Thu Aug 7 15:29:10 2003

In general, the plan sounds good, as Nick says, a flowchart is good. Perhaps
also on the front of the snack machine when it's done? (or at least parts of

A few comments.

On Thu, Aug 07, 2003 at 11:11:17PM +0800, Bernard Blackham wrote:
> On Thu, Aug 07, 2003 at 09:22:47PM +0800, Nick Bannon wrote:
> > > Here's a brain dump of my plans for the UI. Please rip it to pieces.  :)

> Hmmmm, if we limit withdrawls to $1 a time, and at most $3 a day (or
> something) I think it's convenience would outweight the security
> issues.

It it's limited and we keep track if there's abuse, then it should be OK. We
should also be wary of accepting too much deposited money, as that could be
abused likewise.

> I plan to make it so that pressing Reset twice, no matter where you
> are in the menu, will log you out - I think people will catch on. In
> addition to having a 20s timeout.


> What I am rethinking though, is taking wimpier ways out - to allow
> the interface to be as flexible as possible, make the vending
> machine as dumb as possible (just a display, keypad, set of motors
> and coin mech), and have the interface driven from mermaid. Hence
> keypresses would travel to mermaid and display updates back to the
> machine. It might seem a little laggy even over a 9600bps link, but
> this way we only need to flash the ROM as few times as possible.

This is a good idea. If it's difficult to change/improve stuff, things will
be left brokenish. Of course there is then scope for breaking stuff on
mermaid, but at least that is easier to fix. Also swapping ROMs about lots
isn't really the best for the board I would assume.