Hi all,
Using a arduino as an DMX receiver it seems i cant use the Serial port any more.
I use a arduino as a receiver and i want it to send out simple controlls to 2 other arduino's that each handle tasks on their own.
Basically
Arduino1:
In(on Rx) - DMX
Out - 6bytes of information updated every 10/20millis
Arduino2 & 3
should receive these 6bytes, to control stuff(motors and lamps)
How would i best approuch this?
Spark
How far apart are the other Arduino's? You could use I2C or SPI over short distances (few centimetres) or Software serial over longer runs
The can be as close as 1mm apart 
The other arduino's perform high speed timing operations to drive steppers to a position. These are timer and or interrupt based.
SPI, is also interrupt driven, so in theory these could form a clash.
I could have the receiving arduino send a input high on the SPI master arduino and let it send 3bytes. If i do this right after an high puls, these bytes should arrive in time before the next pulse.
But how would i go about having 2 slaves?
Can i somehow block the spi lines so information for arduino a is not triggering interrupts on arduino b, which in theory cpuld just at that moment be busy wih pulsing it's motors?
So basically only allow interrupts for a spi when "ready".
Edit:
Ok i found my answer, i can drive the SS line high, to make it ignore the mosi, miso and clk.