Lpc2000

----- Original Message ----- 
From: "Robert Wood" <robert.wood@...>
To: <lpc2000@yahoogroups.com>
Sent: Monday, March 06, 2006 8:06 PM
Subject: [lpc2000] SPI comms with another micro


> Chaps,
>
> I'd like to pick your collective brains.
>
> I'm using a 2194 that communicates with lots of other devices using all
> four CAN ports and both UARTs. One UART communicates with an AVR which
> does some real time stuff and passes data to the ARM, and the other
> talks to a PC. I need to add another UART, which means I need to somehow
> free up the serial port that talks to the AVR and come up with an
> alternative way of getting the two devices to communicate.
>
> I would do it as a parallel interface using P1 if it wasn't for the
> ridiculous pinout of that port! The next best way seems like it might be
> SPI (as I'm not using the SPI port). I would almost definitely have to
> go to four layer if I did it this way, and I don't want to do that.
>
> Would I be mad to try this? It strikes me from reading about various SPI
> issues on here I might be asking for trouble. I need to get information
> out of the AVR and into the ARM as rapidly as possible and also get
> configuration data from the ARM to the AVR, so I'm assuming I would have
> to change which was master and slave from time to time?
>
> I would add I've done lots of SPI in the past, but always with the micro
> being the master and talking to D/As, EEPROMs etc. I'm wondering how
> difficult it is to get a micro running as a slave, and in particular the
> 2194, as my perception is the LPC family has some SPI issues. (This may
> well be a false impression of course.)
>
> I have thought about using an SPI UART, but I think only Maxim do those
> and I refuse to use Maxim stuff!

I've used the Maxim chip (interfaced to a PIC) and it works OK. I've also 
used 2313 AVRs interfaced to a PIC (using bit-banged SPI on the AVRs) when I 
needed several UARTS. The latter also worked very well.

Leon 

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