user42630: I'm trying to use an Arduino as a slave and was searching for examples which I found many. But apart from the examples, I haven't found any documentation explaining many thing that show up in those examples.
For example, I'd like a document that would state what things like the following are:
-SPCR  
-SPE 
-SPDR 
-ISR 
-SPI_STC_vect
I'm asking this, because I don't and can't just copy an example and hope that it'll work, I really need to know what I'm doing.
Thank you, 
João

user42539: Take a look at Nick Gammon's SPI explanations also. Very good, with timing explained as well.
http://www.gammon.com.au/spi

user-1: You are confusing SPI, a de facto standard, with the Arduino/Atmel hardware support for SPI.
SPCR, SPE and SPDR are registers of the Atmel MCU, part of the hardware support. 
ISR is Interrupt Service Routine and SPI_STC_vect is the vector that point to that code. That is where the data received from the cable is read finally.

42630: <p>I'm trying to use an Arduino as a slave and was searching for examples which I found many. But apart from the examples, I haven't found any documentation explaining many thing that show up in those examples.</p>

<p>For example, I'd like a document that would state what things like the following are:<br>
-SPCR <br> 
-SPE <br>
-SPDR <br>
-ISR <br>
-SPI_STC_vect</p>

<p>I'm asking this, because I don't and can't just copy an example and hope that it'll work, I really need to know what I'm doing.</p>

<p>Thank you, <br>
João</p>
 42539: <p>Take a look at Nick Gammon's SPI explanations also. Very good, with timing explained as well.</p>

<p><a href="http://www.gammon.com.au/spi" rel="nofollow noreferrer">http://www.gammon.com.au/spi</a></p>
 -1: <p>You are confusing SPI, a de facto standard, with the Arduino/Atmel hardware support for SPI.</p>

<p>SPCR, SPE and SPDR are registers of the Atmel MCU, part of the hardware support. </p>

<p>ISR is Interrupt Service Routine and SPI_STC_vect is the vector that point to that code. That is where the data received from the cable is read finally.</p>
