SPI master and slave

Projects Networking, Protocols, and Devices
1

Hi Guys, I've been blocked for 3 weeks now searching for a solution to my problem concerning SPI communication,

So, I need to establish a Spi communication between two arduino, the master sends a lettre 'a' for exemple to the slave, and when the slave receives this lettre, he will do some traitements. In my case, he will set one of his 8 pins to high then read all pins and send the repport back to the master.

the part of sending 'a' and the traitement works fine within the slave, but i can't receive the correcte values in the master, i always receive 0.

can any help me please.

here are the codes.

esclave_spi.ino (1.61 KB)

maitre_spi.ino (1.15 KB)

2

Normally, the SPI bus requires two transfers to get data from the slave. The first transfers the command, and the second just reads the reply.

byte transferAndWait (const byte what)
{
  SPI.transfer (what);
  delayMicroseconds (10);
  byte a = SPI.transfer (0);
  return a;
} // end of transferAndWait