[Opendispense] Coinage progress

Bernard Blackham bernard@blackham.com.au
Thu Aug 7 17:53:02 2003

It's 2am, but I'm finally getting to grips with the SCI Interrupt
handler and the coin mechanism. It appears that the coin mech speaks
on a serial bus, where the first 3 MSBs are an identifier - the coin
mech uses 001. The next bit denotes something I haven't figured out
yet. And then the last 4 bits contain data. So data is actually
transferred in nibbles. And I believe that the data is the value of
money currently in the coin mech in cents (to be confirmed), and not
individual counts of coins inserted.

Which means... we teach our server program on mermaid to speak the
same protocol using a different ID and we can differentiate between
them. It'd either require a tiny box to breakout the serial lines to
mermaid, or alternately, there might be something already like that
on that unconnected cable coming out of the coin mech.

I'm just hoping this still makes sense when I wake up in the
morning. =)



 Bernard Blackham 
 bernard at blackham dot com dot au