[Rcxemul-discussion] Update - 12th Oct 2002

[David E. <d.a...@du...>]

Hi all.

I'm still plodding along! I've implemented much of the serial
communications, which wasn't too easy. I had to learn a lot about
sockets in Unix, so it took a while.

The system now uses a communications protocol to accept commands from
outside the system. I've only implemented one or two messages - enough
to get things running. So far I can send a message to put a byte into
the serial receive register, a message to set the state of a port, and
one to write byte data to a supplied memory location. However, it means
that stepping through the code instruction by instruction isn't really
possible now. I poll for incoming messages every 250 instructions, and
time out after a short (10ms) period. This doesn't seem to slow the
system down too much.

So I now need a method of debugging, so I'm attempting to build a
breakpoint system. Breakpoints will be handled using the communications
protocol. I'm working this way so that an external interface can be
written (I'm going to use Java) to act as a debugging environment.

I've hacked the firmware download code (rcx_comm.c and rcx_comm.h) from
lejos to allow a whole message to be sent to the emulator. When each
byte is sent the appropriate interrupt is dispatched, but from there
it's difficult to work out what is happening (because I can't step
through yet). In theory, a transmit interrupt should be dispatched but
it isn't being. I'll know more about why when I can step through.

That's about it for now... You've been a great audience!
Dave.

PS I'm thinking about using a WikiWeb for the RCXEmul website. Anyone
have any experience setting one of these up?