Lpc2000

laurensswaans wrote:

>Hello,
>
>I've got a design where 2 LPC2129 will be used. They will 
>communicate with eachother. My first guess is that the clocksignals 
>for both controllers should be the same to prevent phase-shift or 
>small frequency differences when using two crystals.
>
>I believe that it is possible to clock the microcontroller by an 
>external clock, so I would like to clock both controllers by one 
>external source.
>
>Has anyone experience with this, or done this before? Are there 
>other issues that require attention when using two controllers in a 
>system? 
>
>I've got one controller that will measure continuously, send the 
>result to the other controller (sender is master), the other 
>controller then has to manipulate this data a bit and send it to 
>either COM or CAN, and control an amplifier or something.
>
>  
>
Pretty much what I'm doing, I have two processors on my board: LPC2106 
doing outside world communications through multiple serial interfaces, 
LPC2138 doing data collection and running an SD card via SPI.

I run both from a 14.745mHz oscillator, not a crystal, then couple the 
processors to the clock signal via 100p cap into the X1 input of the 
PLL.  They work fine.

I don't think you need to be that concerned with phasing the clocks, 
SPI, I2C or plain RS232 is pretty tolerant.

TomW


-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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