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Multi master SPI

Question asked by JonG on Mar 5, 2010
Latest reply on Mar 6, 2010 by PrasanthR



We have some questions to ask regarding switching BF from SPI master to SPI slave and vice versaImage1.png

We are planning to have the following configuration and need some of your advise to see if it’s plausible. We are planning to have 2 x BF561 connected to a microcontroller where the microcontroller acts as the Host. Please advise if the following processes is plausible for BF561 and how best to connect the devices


During boot up:


1.)    BF561 A and B are Masters booting up from its individual 24bit SPI flash


During running,

1.)    Microcontroller becomes the Master and BF561 A and B becomes Slave.

2.)    Microcontroller has 4 CS (chip select, CS0 – CS1  for BF561 A and B respectively and CS2-CS3 for SPI Flash A and B)

3.)    Purpose of having CS2 and CS3 is to program the SPI flash directly from  microcontroller during product deployment

4.)    Protocol communication between microcontroller (as Master) and BF561 A and BF561 B, both DSPs as Slave.

5.)    Another challenging  part is BF561 B will be acting also as a Master to few other peripherals. We know it will be difficult and complicated to have multi-master


We are just concern about hardware conflict for the BF561 as it boots as master and then switches to slave. Do you reckon this processes is plausible and how best should we configure the hardware and software together? If you can assist, you can help sketch on the figures.

Currently, fig 1, we have configured a single BF as a SPI Master to boot up from a 24 bit SPI Flash (as slave). Quite easily done.