Lpc2000

Kris,

I read the I2C spec from philips but one thing I am totally unclear 
on! If I have 2 masters and both transmited to eachother at the same 
time. I know one will win the arbitration but since there is only 
one data register in the LPC chip, on the chip that lost 
arbitration, the TX data will not be transmitted and will be over 
written by the the RX data. Is this right? collision? It seems like 
it is a bad idea to have 2 masters transmitting te each other.

Gus

--- In lpc2000@yahoogroups.com, "microbit" <microbit@c...> wrote:
> Hi Gus,
> 
> > I need to move data fast between 2 I2C devices ASAP. One device 
is a 
> > PIC18F458 micro and the other is an LPC2114 micro. 
> > 
> > 1) Is it best if I set up one as a slave and the other as master 
or 
> > it is better to set them up both as master/slave?
> 
> It depends on who is likely to start the transfer.
>  
> > 2) It seems to be too slow to do stop/start conditions when 
sending 
> > data. If data is going both dirrections at the same time, is 
there a 
> > way to come over start/stop condisions?
> 
> Data can't go in both directions at same time, there's only clock 
& data.
> If 2 devices want the bus, there must be "arbitration".
> The data line is pulled low (perhaps on both sides), and then an 
ACK
> is expected.
> Due to this arbitration, one device is expected to acquire and one 
to relinquish the bus.
> (Hence why I2C must be wired-OR).
> 
> > 3) What address am I allowed to use on I2C? Is there legal 
issues on 
> > using sertain I2C addresses? I can only use 7-bit addressing
> 
> Dunno, if you just have these 2 devices, I'd do as I please 
(proviso you won't connect
> I2C peripherals later).
> Else the device has an I2C address dictated by what kind it is, 
and eg. with EEPROM
> you'll get 3 ext address pins you can preset.
> 
> B rgds
> Kris
> 
> 
> [Non-text portions of this message have been removed]