Communication between two STR910 via SPI

euriarte · ‎2009-03-02

Posted on March 03, 2009 at 06:35

euriarte · ‎2011-05-17

Posted on May 17, 2011 at 09:57

Hello,

First of all, sorry because my English is quite bad.

I need to comunicate two STR910 micro via SPI. I've chosen SSP1 port for the communication. One of the micros will be the master, and other will be the slave. No other slaves in SPI1 port. My question is: It is necesary to manage de slave micro NSS pin? If I have NSS pin not connected, data can be received by the slave?

Thanks in advance.

[ This message was edited by: euriarte on 27-02-2009 11:02 ]

kais · ‎2011-05-17

Posted on May 17, 2011 at 09:57

Hello,

The following paragraph is extracted from the STR9 reference manual

''9.3.4 Slave Select management

The NSS Slave Select signal is output from the Master and received by the Slave.There are two cases depending on the data/clock timing relationship (see Figure 67):

â—� If CPHA=1 (data latched on 2nd clock edge):

NSS must be held low during the entire transmission. This implies that in single slave applications the NSS pin can be tied to VSS.â€�

May this response to your question.

Kind regards,

Eris.

null

euriarte · ‎2011-05-17

Posted on May 17, 2011 at 09:57

Hello eris,

I have connected NSS slave pin to GND and the slave receive data correctly.

And it is a must to connect NSS master pin to VCC if I want to transmit data of the slave to the master? I'm working with a board that havenÂ´t this connection...

Thanks in advance.