SPI interface with other board_AVR_ESK1100 or among Arduino itself

Yes , It is 10X probe of Tektronix TDS2024C(200MHz/100MHz, 10MOhm/<12pF 300V CAT II).

Hi...!!

I am reading http://www.gammon.com.au/spi again and again and trying to grasp SPI, but not getting expected results.

Can we write the codes like this, are these correct codes for mater and slave

//Master sending data
#include <SPI.h>// include the SPI library:
#define SCK_PIN   13
#define MISO_PIN  12
#define MOSI_PIN  11

const int spidata = 10;//Pin 11 is data(MOSI) and pin 13 SCK ,set pin 10(SS) as the slave select for the digital pot:
int array[30] = {0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00,0x00, 0x00, 0x00, 0x00, 0x08,0x00, 0x00, 0x00, 0x00, 0x00, 0x0A, 0x00, 0x00, 0x00, 0x00,0x00};
int chr;

void setup() {
 
  pinMode (spidata, OUTPUT);// set the spi_data_pin as an output:
 
  SPI.begin();// initialize SPI:
  Serial.begin(115200);
  SPI.setDataMode(SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;
  SPI.setBitOrder(LSBFIRST);
  digitalWrite(spidata,HIGH);
 
}

void loop() {
  int data[10];
  char ch;
 

    //delay(14);
   digitalWrite(spidata,LOW);
   SPI.transfer(array[0]);
   SPI.transfer(array[1]);
   digitalWrite(spidata,HIGH);
    //delay(14);
   
   digitalWrite(spidata,LOW);
   SPI.transfer(array[2]);
   SPI.transfer(array[3]);
   digitalWrite(spidata,HIGH);
   // delay(14);
   
   digitalWrite(spidata,LOW);
   SPI.transfer(array[4]);
   SPI.transfer(array[5]);
   digitalWrite(spidata,HIGH);
    delay(1);
   
   digitalWrite(spidata,LOW);
   SPI.transfer(array[6]);
   SPI.transfer(array[7]);
   digitalWrite(spidata,HIGH);
   
     digitalWrite(spidata,LOW);
   SPI.transfer(array[8]);
   SPI.transfer(array[9]);
   digitalWrite(spidata,HIGH);
   
      digitalWrite(spidata,LOW);
   SPI.transfer(array[10]);
   SPI.transfer(array[11]);
   digitalWrite(spidata,HIGH);
  delay(1);
   
     digitalWrite(spidata,LOW);
   SPI.transfer(array[12]);
   SPI.transfer(array[13]);
   digitalWrite(spidata,HIGH);
   // delay(14);
   
   digitalWrite(spidata,LOW);
   SPI.transfer(array[14]);
   SPI.transfer(array[15]);
   digitalWrite(spidata,HIGH);
   // delay(14);
   
   digitalWrite(spidata,LOW);
   SPI.transfer(array[16]);
   SPI.transfer(array[17]);
   digitalWrite(spidata,HIGH);
   delay(1);
   
     digitalWrite(spidata,LOW);
   SPI.transfer(array[18]);
   SPI.transfer(array[19]);
   digitalWrite(spidata,HIGH);
   
      digitalWrite(spidata,LOW);
   SPI.transfer(array[20]);
   SPI.transfer(array[21]);
   digitalWrite(spidata,HIGH);
    digitalWrite(spidata,LOW);
   SPI.transfer(array[22]);
   SPI.transfer(array[23]);
   digitalWrite(spidata,HIGH);
  //  delay(14);
   

    }

Slave receiving data from master then sending the data back to master, is it right.

//Slave receiving data from master and sending back data
#include "pins_arduino.h"
#include <SPI.h>
#define SS 10
int dat[24] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14};
byte c;
void ss_falling()
{
  c = 0;
}

void setup (void)
{

  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  // interrupt for SS falling edge
  attachInterrupt (0, ss_falling, FALLING);
   // disable timer interrupts
  TIMSK0 = 0;
  
}  // end of setup


// SPI interrupt routine
ISR (SPI_STC_vect)
{
  c = SPDR;
  
 if(c == 0x04)
  {
    digitalWrite(SS, LOW);
  SPI.transfer(dat[0]);
  SPI.transfer(dat[1]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[2]);
  SPI.transfer(dat[3]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[4]);
  SPI.transfer(dat[5]);
   digitalWrite(SS, HIGH);
 }
 
  else if(c == 0x06)
  {
   digitalWrite(SS, LOW);
  SPI.transfer(dat[6]);
  SPI.transfer(dat[7]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[8]);
  SPI.transfer(dat[9]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[10]);
  SPI.transfer(dat[11]);
   digitalWrite(SS, HIGH);
 }
  else
 SPDR = 0x00;    // what to return to the master
 


}  // end of interrupt service routine (ISR) SPI_STC_vect

void loop (void)
{
 
}  // end of loop

TEK0000.BMP (76.1 KB)

Nick had this

// SPI interrupt routine
ISR (SPI_STC_vect)
{
  byte c = SPDR;  // what we received from the master
  SPDR = 0;    // what to return to the master
}  // end of ISR SPI_STC_vect

You have this

ISR (SPI_STC_vect)
{
  c = SPDR;
  
 if(c == 0x04)
  {
    digitalWrite(SS, LOW);
  SPI.transfer(dat[0]);
  SPI.transfer(dat[1]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[2]);
  SPI.transfer(dat[3]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[4]);
  SPI.transfer(dat[5]);
   digitalWrite(SS, HIGH);
 }
 
  else if(c == 0x06)
  {
   digitalWrite(SS, LOW);
  SPI.transfer(dat[6]);
  SPI.transfer(dat[7]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[8]);
  SPI.transfer(dat[9]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[10]);
  SPI.transfer(dat[11]);
   digitalWrite(SS, HIGH);
 }
  else
 SPDR = 0x00;    // what to return to the master
 


}  // end of interrupt service routine (ISR) SPI_STC_vect

Do you see the difference?

Nick said this

The ISR has to be fast, because if you don't change SPDR fast enough, the incorrect data will be sent on the next transfer.

You have an ISR as long as your arm that will take about three weeks to execute.

Nick said this

you need to allow time for the slave to do whatever it needs to do, and set up a response (ie. set SPDR).

Your code has the odd delay but not after every transfer.

On the master you are toggling the for every two bytes, why?

On the slave you do similar on the SS pin. You DON'T touch the SS pin on the slave. You DON'T call SPI.transfer() on the slave(). You DON'T do nothing on the slave except put data in the SPDR register. If you need to parse the first byte as a command you'd better do it real quick and use the results to point to a different array of bytes to return to the master.


Rob

I know I'm going to regret this but here's my quick version of one way to do the slave

#define MAX_BYTES 4  // is there 4 bytes? if not change this and the arrays.

byte cmd_04_data[MAX_BYTES] = {1,2,3,4}; // you fill in the numbers 
byte cmd_06_data[MAX_BYTES] = {5,6,7,8};
byte * data_ptr;
int byte_count = 0;

ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0) {
      // set a pointer to one or other array based on the byte just received
      data_ptr = (c == 0x04) ? cmd_04_data : cmd_06_data; 
  }
  SPDR = *(data_ptr + byte_count);
  byte_count++;   
  if (byte_count = MAX_BYTES) byte_count = 0;
}

It compiles but I can't test it.


Rob

Graynomad:
Nick had this

// SPI interrupt routine

ISR (SPI_STC_vect)
{
  byte c = SPDR;  // what we received from the master
  SPDR = 0;    // what to return to the master
}  // end of ISR SPI_STC_vect




You have this



ISR (SPI_STC_vect)
{
  c = SPDR;
 
if(c == 0x04)
  {
    digitalWrite(SS, LOW);
  SPI.transfer(dat[0]);
  SPI.transfer(dat[1]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[2]);
  SPI.transfer(dat[3]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[4]);
  SPI.transfer(dat[5]);
   digitalWrite(SS, HIGH);
}

else if(c == 0x06)
  {
   digitalWrite(SS, LOW);
  SPI.transfer(dat[6]);
  SPI.transfer(dat[7]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[8]);
  SPI.transfer(dat[9]);
   digitalWrite(SS, HIGH);
   
   digitalWrite(SS, LOW);
  SPI.transfer(dat[10]);
  SPI.transfer(dat[11]);
   digitalWrite(SS, HIGH);
}
  else
SPDR = 0x00;    // what to return to the master

}  // end of interrupt service routine (ISR) SPI_STC_vect




Do you see the difference?

Nick said this



> The ISR has to be fast, because if you don't change SPDR fast enough, the incorrect data will be sent on the next transfer.



You have an ISR as long as your arm that will take about three weeks to execute.

Nick said this



> you need to allow time for the slave to do whatever it needs to do, and set up a response (ie. set SPDR).



Your code has the odd delay but not after every transfer.

On the master you are toggling the for every two bytes, why?

On the slave you do similar on the SS pin. You DON'T touch the SS pin on the slave. You DON'T call SPI.transfer() on the slave(). You DON'T do nothing on the slave except put data in the SPDR register. If you need to parse the first byte as a command you'd better do it real quick and use the results to point to a different array of bytes to return to the master.


______
Rob

Hi...!!!

Thanks. More than two SPI.transfer(); does not work fine and 2 bytes of data transfer gives continuous 16clock pulse.
Following code does not work fine with SPDR = data; and I want to send back more than 10 data. And I am not able to give proper delay.
Can you please tell me how much delay I should give at Master side or Slave side.

#include "pins_arduino.h"
#include <SPI.h>
#define SS 10
int dat[24] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14};
byte c;
void ss_falling()
{
  c = 0;
}

void setup (void)
{

  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  // interrupt for SS falling edge
  attachInterrupt (0, ss_falling, FALLING);
   // disable timer interrupts
  TIMSK0 = 0;
  
}  // end of setup


// SPI interrupt routine
ISR (SPI_STC_vect)
{
  c = SPDR;
  
  if(c == 0x04)
  {
    
    SPDR = dat[0];
   
 }
 
   else if(c == 0x06)
  {
    SPDR = dat[1];
   
 }
  else
 SPDR = 0x00;    // what to return to the master
 


}  // end of interrupt service routine (ISR) SPI_STC_vect

void loop (void)
{
 
}  // end of loop

Graynomad:
I know I'm going to regret this but here's my quick version of one way to do the slave

#define MAX_BYTES 4  // is there 4 bytes? if not change this and the arrays.

byte cmd_04_data[MAX_BYTES] = {1,2,3,4}; // you fill in the numbers
byte cmd_06_data[MAX_BYTES] = {5,6,7,8};
byte * data_ptr;
int byte_count = 0;

ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0) {
      // set a pointer to one or other array based on the byte just received
      data_ptr = (c == 0x04) ? cmd_04_data : cmd_06_data;
  }
  SPDR = *(data_ptr + byte_count);
  byte_count++;   
  if (byte_count = MAX_BYTES) byte_count = 0;
}




It compiles but I can't test it. 

_____
Rob

Hi..!!

This code gives following result, which is attached here, blue line is MISO yellow MOSi and Pink line is SCK.

#define MAX_BYTES 4  // is there 4 bytes? if not change this and the arrays.

byte cmd_04_data[MAX_BYTES] = {1,2,3,4}; // you fill in the numbers 
byte cmd_06_data[MAX_BYTES] = {5,6,7,8};
byte * data_ptr;
int byte_count = 0;
void setup (void)
{
}
ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0) {
      // set a pointer to one or other array based on the byte just received
      data_ptr = (c == 0x04) ? cmd_04_data : cmd_06_data; 
  }
  SPDR = *(data_ptr + byte_count);
  byte_count++;   
  if (byte_count = MAX_BYTES) byte_count = 0;
} 
void loop (void)
{
 
}  // end of loop

TEK0000.BMP (76.1 KB)

TEK0001.BMP (76.1 KB)

That wasn't a stand-alone program, what happened to all your setup() code (most or which you don't need anyway I think).


Rob

[code][quote author=Nick Gammon link=topic=120454.msg999023#msg999023 date=1353098493]
[quote author=ranjeetray link=topic=120454.msg998331#msg998331 date=1353063009]
Can we do like this, after receiving data can we check(if condition) data and then send back data to master like this.
[/quote]

I really don't know what you are trying to do. You are doing an SPI.transfer in the middle of the ISR?

You send back data to the master [b]by assigning to SPDR in the interrupt service routine[/b]. No other way. What are you thinking?
[/quote]

Hi...!!

This way(SPDR = dat[0]) also it is not able to send back data to Master, and I am not able to give delay properly and synchronize with master. Slave is not getting chance to send back data, I think so.


[code]

#include "pins_arduino.h"
#include <SPI.h>
#define SS 10
int dat[24] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14};
byte c;
void ss_falling()
{
  c = 0;
}

void setup (void)
{

  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  // interrupt for SS falling edge
  attachInterrupt (0, ss_falling, FALLING);
   // disable timer interrupts
  TIMSK0 = 0;
  
}  // end of setup


// SPI interrupt routine
ISR (SPI_STC_vect)
{
  c = SPDR;
  
  if(c == 0x04)
  {
    
    SPDR = dat[0];
   
 }
 
   else if(c == 0x06)
  {
    SPDR = dat[1];
   
 }
  else
 SPDR = 0x00;    // what to return to the master
 


}  // end of interrupt service routine (ISR) SPI_STC_vect

void loop (void)
{
 
}  // end of loop

[/code][/code]

Graynomad:
That wasn't a stand-alone program, what happened to all your setup() code (most or which you don't need anyway I think).


Rob

Hi..!!

This code give following results, which have been attached here.

#include "pins_arduino.h"
#include <SPI.h>

#define MAX_BYTES 4  // is there 4 bytes? if not change this and the arrays.

byte cmd_04_data[MAX_BYTES] = {1,2,3,4}; // you fill in the numbers 
byte cmd_06_data[MAX_BYTES] = {5,6,7,8};
byte * data_ptr;
int byte_count = 0;
void setup (void)
{
  
  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  // interrupt for SS falling edge
  //attachInterrupt (0, ss_falling, FALLING);
   // disable timer interrupts
  TIMSK0 = 0;
}
ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0) {
      // set a pointer to one or other array based on the byte just received
      data_ptr = (c == 0x04) ? cmd_04_data : cmd_06_data; 
  }
  SPDR = *(data_ptr + byte_count);
  byte_count++;   
  if (byte_count = MAX_BYTES) byte_count = 0;
} 
void loop (void)
{
 
}  // end of loop

TEK0000.BMP (76.1 KB)

TEK0001.BMP (76.1 KB)

I can't make out anything from the scope screen shots, there's obviously something happening though.

Tell you what I'll do, against my better judgement I'll try to write you some code for both ends based on what I think you want to do.


Rob

Graynomad:
That wasn't a stand-alone program, what happened to all your setup() code (most or which you don't need anyway I think).


Rob

Hi..!!

With this code , attached result is coming.

#include "pins_arduino.h"
#include <SPI.h>

#define size_data 4  // is there 4 bytes? if not change this and the arrays.

byte send_04_data[size_data] = {1,2,3,7}; // you fill in the numbers 
byte send_06_data[size_data] = {3,8,7,9};
byte * data_ptr;
int byte_count = 0;
void setup (void)
{
  
  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  // interrupt for SS falling edge
  //attachInterrupt (0, ss_falling, FALLING);
   // disable timer interrupts
  TIMSK0 = 0;
}
ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0)
  {
     
      data_ptr = (c == 0x04) ? send_04_data : send_06_data; 
  
  SPDR = *(data_ptr + byte_count);
  byte_count++; }  
  else 
  
  {
    SPDR = 0;      //******** Added
  
  }
  if (byte_count = size_data) 
  byte_count = 0;
} 
void loop (void)
{
 
}  // end of loop

TEK0014.BMP (76.1 KB)

TEK0011.BMP (76.1 KB)

Graynomad:
I can't make out anything from the scope screen shots, there's obviously something happening though.

Tell you what I'll do, against my better judgement I'll try to write you some code for both ends based on what I think you want to do.


Rob

Thank You.

It will be really a great help for me.

Here's some code. I took the razor to what you had and removed everything not required to prove the concept. Hopefully I didn't go too far. The master could still be a lot smaller.

Master

//Master sending data
#include <SPI.h>// include the SPI library:
#define SS_PIN   10

int command_array[] = {0x04, 0x06, 0x08, 0x0A};
int returned_data[4];

void setup() {
  
  pinMode (SS_PIN, OUTPUT);// set the spi_data_pin as an output:

  Serial.begin(115200);
  
  SPI.begin();
  SPI.setDataMode(SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;
  SPI.setBitOrder(LSBFIRST);
 
}

void loop() {
    
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(command_array[0]);       // send command
    delay(1);                             // give the slave some time
    returned_data[0] = SPI.transfer(0);   // get response
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[1]); 
    returned_data[1] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[2]); 
    returned_data[2] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[3]); 
    returned_data[3] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    Serial.print (returned_data[0]);
    Serial.print (',');
    Serial.print (returned_data[1]);
    Serial.print (',');
    Serial.print (returned_data[2]);
    Serial.print (',');
    Serial.println (returned_data[3]);
  
}

Slave

byte response_data[] = {-1,-1,-1,-1,'4',-1,'6',-1,'8',-1,'A'}; 

void setup (void) {
  
  pinMode(MISO, OUTPUT); // have to send on master in, *slave out*
  SPCR |= _BV(SPE);   // turn on SPI in slave mode
  SPCR |= _BV(SPIE);  // turn on interrupts
 
}  

void loop () {}

ISR (SPI_STC_vect) {
  byte command = SPDR;

  SPDR = response_data[command];

}

See if that does anything useful.


Rob

ranjeetray:
Hi...!!

I am reading http://www.gammon.com.au/spi again and again and trying to grasp SPI, but not getting expected results.

Can we write the codes like this, are these correct codes for mater and slave
...
Slave receiving data from master then sending the data back to master, is it right.

...

// SPI interrupt routine
ISR (SPI_STC_vect)
{
 c = SPDR;
 
if(c == 0x04)
 {
   digitalWrite(SS, LOW);
 SPI.transfer(dat[0]);
 SPI.transfer(dat[1]);
  digitalWrite(SS, HIGH);
 
  digitalWrite(SS, LOW);
 SPI.transfer(dat[2]);
 SPI.transfer(dat[3]);
  digitalWrite(SS, HIGH);
 
  digitalWrite(SS, LOW);
 SPI.transfer(dat[4]);
 SPI.transfer(dat[5]);
  digitalWrite(SS, HIGH);
}

else if(c == 0x06)
 {
  digitalWrite(SS, LOW);
 SPI.transfer(dat[6]);
 SPI.transfer(dat[7]);
  digitalWrite(SS, HIGH);
 
  digitalWrite(SS, LOW);
 SPI.transfer(dat[8]);
 SPI.transfer(dat[9]);
  digitalWrite(SS, HIGH);
 
  digitalWrite(SS, LOW);
 SPI.transfer(dat[10]);
 SPI.transfer(dat[11]);
  digitalWrite(SS, HIGH);
}
 else
SPDR = 0x00;    // what to return to the master

}  // end of interrupt service routine (ISR) SPI_STC_vect
...

Look, ranjeetray, you are just ignoring everything I am saying. I said this:

You do not use SPI.transfer in the ISR. Do you have trouble understanding that?

You are ignoring me, you are just making stuff up, and then taking screen shots of the scope output. It won't work.

Graynomad has offered to write an example but that won't help if you don't make an attempt to understand things. Don't just copy and paste and hope for the best.

Graynomad:
Here's some code. I took the razor to what you had and removed everything not required to prove the concept. Hopefully I didn't go too far. The master could still be a lot smaller.

Master

//Master sending data

#include <SPI.h>// include the SPI library:
#define SS_PIN   10

int command_array[] = {0x04, 0x06, 0x08, 0x0A};
int returned_data[4];

void setup() {
 
 pinMode (SS_PIN, OUTPUT);// set the spi_data_pin as an output:

Serial.begin(115200);
 
 SPI.begin();
 SPI.setDataMode(SPI_MODE2);
 SPI.setClockDivider(SPI_CLOCK_DIV64) ;
 SPI.setBitOrder(LSBFIRST);

}

void loop() {
   
   digitalWrite(SS_PIN,LOW);
   SPI.transfer(command_array[0]);       // send command
   delay(1);                             // give the slave some time
   returned_data[0] = SPI.transfer(0);   // get response
   digitalWrite(SS_PIN,HIGH);

digitalWrite(SS_PIN,LOW);
   delay(1);
   SPI.transfer(command_array[1]);
   returned_data[1] = SPI.transfer(0);
   digitalWrite(SS_PIN,HIGH);

digitalWrite(SS_PIN,LOW);
   delay(1);
   SPI.transfer(command_array[2]);
   returned_data[2] = SPI.transfer(0);
   digitalWrite(SS_PIN,HIGH);

digitalWrite(SS_PIN,LOW);
   delay(1);
   SPI.transfer(command_array[3]);
   returned_data[3] = SPI.transfer(0);
   digitalWrite(SS_PIN,HIGH);

Serial.print (returned_data[0]);
   Serial.print (',');
   Serial.print (returned_data[1]);
   Serial.print (',');
   Serial.print (returned_data[2]);
   Serial.print (',');
   Serial.println (returned_data[3]);
 
}




Slave


byte response_data[] = {-1,-1,-1,-1,'4',-1,'6',-1,'8',-1,'A'};

void setup (void) {
 
 pinMode(MISO, OUTPUT); // have to send on master in, slave out
 SPCR |= _BV(SPE);   // turn on SPI in slave mode
 SPCR |= _BV(SPIE);  // turn on interrupts

}

void loop () {}

ISR (SPI_STC_vect) {
 byte command = SPDR;

SPDR = response_data[command];

}




See if that does anything useful.

______
Rob
//Master sending data
#include <SPI.h>// include the SPI library:
#define SS_PIN   10

int command_array[] = {0x04, 0x06, 0x08, 0x0A};
int returned_data[4];

void setup() {
  
  pinMode (SS_PIN, OUTPUT);// set the spi_data_pin as an output:

  Serial.begin(115200);
  
  SPI.begin();
  SPI.setDataMode(SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;
  SPI.setBitOrder(LSBFIRST);
 
}

void loop() {
    
    digitalWrite(SS_PIN,LOW);
    SPI.transfer(command_array[0]);       // send command
    delay(1);                             // give the slave some time
    returned_data[0] = SPI.transfer(0);   // get response
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[1]); 
    returned_data[1] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[2]); 
    returned_data[2] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    digitalWrite(SS_PIN,LOW);
    delay(1);
    SPI.transfer(command_array[3]); 
    returned_data[3] = SPI.transfer(0);
    digitalWrite(SS_PIN,HIGH);

    Serial.print (returned_data[0]);
    Serial.print (',');
    Serial.print (returned_data[1]);
    Serial.print (',');
    Serial.print (returned_data[2]);
    Serial.print (',');
    Serial.println (returned_data[3]);
  
}

With the following code, attached image 2 and TEK0002 are the output at Master Serial Monitor and on Oscilloscope:

#include "pins_arduino.h"
#include <SPI.h>

#define size_data 4  // is there 4 bytes? if not change this and the arrays.

byte send_04_data[size_data] = {1,2,3,7}; // you fill in the numbers 
byte send_06_data[size_data] = {3,8,7,9};
byte * data_ptr;
int byte_count = 0;
void setup (void)
{
  
  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

  // turn on SPI in slave mode
  SPCR |= _BV(SPE);

  // turn on interrupts
  SPCR |= _BV(SPIE);
  
 // disable timer interrupts
  TIMSK0 = 0;
  
}
ISR (SPI_STC_vect) {
  byte c = SPDR;
  if (byte_count == 0)
  {
     
      data_ptr = (c == 0x04) ? send_04_data : send_06_data; 
  
  SPDR = *(data_ptr + byte_count);
  byte_count++; }  
  else 
  
  {
    SPDR = 0;
  
  }
  if (byte_count = size_data) 
  byte_count = 0;
} 
void loop (void)
{
 
}  // end of loop

With the following code image 3 and TEK0006 are output:

#include "pins_arduino.h"
#include <SPI.h>
byte response_data[] = {1,2,-1,3,'4',-1,'6',-1,'8',-1,'A'}; 
void setup (void)
{
  
  // have to send on master in, *slave out*
  pinMode(MISO, OUTPUT);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode (SPI_MODE2);
  SPI.setClockDivider(SPI_CLOCK_DIV64) ;
  // turn on SPI in slave mode
  SPCR |= _BV(SPE);
  // turn on interrupts
  SPCR |= _BV(SPIE);
  // disable timer interrupts
  TIMSK0 = 0;
 
}

void loop (void)
{
 
}  // end of loop

ISR (SPI_STC_vect) {

  byte command = SPDR;

  SPDR = response_data[command];

} 

But Slave is not sending data back properly.

TEK0002.BMP (76.1 KB)

2.bmp (918 KB)

3.bmp (885 KB)

TEK0006.BMP (76.1 KB)

Do you deliberately not use the code provided to wind us up or what? Why did you change the array and put all the SPI setup code back in?

Use the slave code I posted. It may not be correct but it's a lot better than what you have I think.


Rob

if (byte_count = size_data) 

byte_count = 0;

I think it's a troll.

I've worn a groove in my tablet's screen scrolling through this thread.
Nick, you deserve a medal.

AWOL:
I've worn a groove in my tablet's screen scrolling through this thread.
Nick, you deserve a medal.

I appreciate for your effort.

AWOL:
I've worn a groove in my tablet's screen scrolling through this thread.
Nick, you deserve a medal.

Hi...!!!

I have tried all the possible combinations , Slave is not able to send back data to master for each if conditions.

#include "pins_arduino.h"

#include <SPI.h>

#define SS 10

int dat[24] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14};

byte c;

int m, n ;

void setup (void)

{

  // have to send on master in, *slave out*

  pinMode(MISO, OUTPUT);

  SPI.setBitOrder(MSBFIRST);

  SPI.setDataMode (SPI_MODE2);

  SPI.setClockDivider(SPI_CLOCK_DIV64) ;

 

  // turn on SPI in slave mode

  SPCR |= _BV(SPE);

 

  // turn on interrupts

  SPCR |= _BV(SPIE);

 

 // disable timer interrupts

  TIMSK0 = 0;

 

}  // end of setup

 

 

// SPI interrupt routine

ISR (SPI_STC_vect)

{

  c = SPDR;

  if(c == 0x00)

 {

  SPDR = 0x01;

}

  else if(c == 0x06)

 {

 

  SPDR = 0x02;

 }

  else if(c == 0x08)

 {

 

  SPDR = 0x03;

 }

   else if(c == 0x0A)

 {

 

  SPDR = 0x07;

 }

 

else

 SPDR = 0;    // what to return to the master

 

}  // end of interrupt service routine (ISR) SPI_STC_vect

 

void loop (void)

{

 

}  // end of loop