Multi-Slave system using SPI in PSoC 1

[Anonymous]

 Is it possible to implement a single master - multi-slave system in PSoC 1? How many maximum slaves are possible?

[Bob_Marlowe]

The selected slave is addressed by a -Select line, so you need one output pin for each slave you want to talk to. So the number of free pins on your selected device limits the number of slaves you may talk to.

   

You need

   

MOSI

   

MISO

   

CLK

   

-SSelect * Number of slaves

   

Have a look into the SPIM datasheet, it explains everything quite clear.

       

Bob

[ETRO_SSN583]

If you used I2C to effect the approach the number of slaves allowed

   

would be governed by either / both the addressing mode and buss

   

C loading. 7 bit addressing would support 128 slaves if the buss loading

   

is within spec.

       

Of course I2C much slower than SPI.

       

Regards, Dana.

[ETRO_SSN583]

If you elect to stay with SPI, slaves limited by pins available on PSOC

   

for chip select, unless you use chained mode. And higher buss speeds

   

imply shorter distances, unless you implement some type of LVDS

   

signaling. And of course you have paralled pins like clk on all slaves,

   

so buss C a factor for the speed you are trying to operate at.

       

Regards, Dana.

[ETRO_SSN583]

Forgot these -

       

http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

       

http://www.ti.com/lit/an/slyt441/slyt441.pdf

       

Regards, Dana.

[Anonymous]

 Yes, it is possible to implement single master - multi slave system in PSoC1. Two normally used configurations for this are the Daisy chained multi slave system and parallel multislave system..

   

In Daisy chained multi slave system the output of one slave connects to the input of another and there is only one slave select line on the master end. To send the data to the nth slave in this case , the master must initiate n transactions. The number of slaves in this case is limited by the amount of delay acceptable in the design.

   

In parallel multi slave system , the slaves are connected in parallel and the master must provide separete slave select line for each slave. The number of slaves in this case is limited by the number of free pins available.

   

A detailed explanation on SPI working in PSoC1 can be found in AN51234.- http://www.cypress.com/?rID=34609

   

and the SPIM user module datasheet - http://www.cypress.com/?rID=3054