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Topic: SPI interface with other board_AVR_ESK1100 or among Arduino itself (Read 12200 times) previous topic - next topic

ranjeetray


OK, now re-read reply #4 and explain why you ignored his suggestion.


Respected Sir

Thanks a lot for your kind reply. I have tried with his suggestion also but still I was getting value 0. Please explain me in depth. I am doing something wrong which I am not able to understand. Kindly guide me.

I had used this code also
Code: [Select]

byte WriteByte (byte value) {
  SPDR = value ;
  while (!(SPSR & (1<<SPIF)))
  {}
  return SPDR ;
}

ranjeetray


I think your WriteByte routine is failing to complete the process - it reads SPSR but doesn't read SPDR once there's a byte so the hardware never clears ready for the next byte?  To quote the datasheet:
Quote
the SPIF bit is cleared by first reading the SPI Status Register with SPIF set, then accessing the SPI Data Register (SPDR)


  How about rewriting WriteByte thus:
Code: [Select]


byte WriteByte (byte value) {
  SPDR = value ;
  while (!(SPSR & (1<<SPIF)))
  {}
  return SPDR ;
}

(So easy to miss a semicolon after a while, use a blank block instead, harder to misread)


Respected Sir

I have used this code also but getting the same value as 0.
Please explain me how to make SPDR to work.


Code: [Select]

byte WriteByte (byte value) {
  SPDR = value ;
  while (!(SPSR & (1<<SPIF)))
  {}
  return SPDR ;
}

Nick Gammon

Code: [Select]

 byte ReadByte(void) {
 
 while(!(SPSR & (1<<SPIF)))
   return SPDR;
}



Do you see a similar problem here?

MarkT said:

Quote
(So easy to miss a semicolon after a while, use a blank block instead, harder to misread)
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

ranjeetray

#18
Aug 29, 2012, 09:40 am Last Edit: Aug 29, 2012, 09:55 am by ranjeetray Reason: 1

Code: [Select]

 byte ReadByte(void) {
 
 while(!(SPSR & (1<<SPIF)))
   return SPDR;
}



Do you see a similar problem here?

MarkT said:

Quote
(So easy to miss a semicolon after a while, use a blank block instead, harder to misread)



Respected Sir

When I use ; it goes in infinite loop and does not give any output and without ; it gives output as
Output:
Code: [Select]

Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0
Read value
0


Sir ,
Is this code correct, please suggest if something is wrong:
Code: [Select]

#include <SPI.h>// include the SPI library:

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:

void setup() {
 
 pinMode (spidata, INPUT);// set the spi_data_pin as an output:
 SPI.setDataMode(SPI_MODE3);
 SPI.setClockDivider(SPI_CLOCK_DIV8);
 SPI.begin();// initialize SPI:
 Serial.begin(9600);}
 
 byte ReadByte(void) {
 
 while(!(SPSR & (1<<SPIF)));
   return SPDR;
}

void loop() {
 
     int rxData;
 
   digitalWrite(spidata,LOW);
     rxData = ReadByte();
     Serial.println("Read value ");
    Serial.println(rxData, DEC);
   digitalWrite(spidata,HIGH);
  delay(1500);
}


Nick Gammon

Will you please explain why you are not using SPI.transfer() ?
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

MarkT

That's a good point - SPI.transfer will work for both master and slave I think (master mode doesn't require the SPDR to be read, but transfer does this anyway).
[ I won't respond to messages, use the forum please ]

Graynomad

There was an almost exact same problem on this thread

http://arduino.cc/forum/index.php/topic,118712.0.html

Same code even.

I still don't know why it didn't work but using SPI.transfer() fixed it.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

ranjeetray


There was an almost exact same problem on this thread

http://arduino.cc/forum/index.php/topic,118712.0.html

Same code even.

I still don't know why it didn't work but using SPI.transfer() fixed it.

______
Rob


Dear Sir

Thanks a lot for your kind support.

Can you please provide us the both master and slave codes, it will be great help for me.

Thanks & Regards..

ranjeetray

#23
Aug 30, 2012, 07:15 am Last Edit: Aug 30, 2012, 07:21 am by ranjeetray Reason: 1

Will you please explain why you are not using SPI.transfer() ?


Respected Sir

Thanks a lot for your kind support. Now I am able to receive data form master but after receiving I want to send some data to master back, how can we do this. I have used SPI.transfer() in the master/data-sending code.
Working code.

Sending data code:
Code: [Select]

#include <SPI.h>// include the SPI library:

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 mm =0;

void setup() {
 
 pinMode (spidata, OUTPUT);// set the spi_data_pin as an output:
 
 SPI.begin();// initialize SPI:
 Serial.begin(9600);
}

void loop() {
   
     digitalWrite(spidata,LOW);
     SPI.transfer(0x3b); //  send in the address and value via SPI:
     digitalWrite(spidata,HIGH);// take the SS pin high to de-select the chip:
     delay(1500);
   }



Receiving data code:
Code: [Select]

#include <SPI.h>
#include <stdio.h>
#include <avr/io.h>
#include <stdlib.h>

#define MOSI 11
#define MISO  12
#define SCK  13
#define SS 10

int data = 0;
char buff[8];


void setup()
{
 pinMode(MOSI, INPUT);
 pinMode(MISO, OUTPUT);
 pinMode(SCK,INPUT);
 pinMode(SS,INPUT);

 Serial.begin(9600);
 SPCR = 0x40;  // Enable SPI in slave mode
//  SPI.begin();
 delay(500);
 
}

void loop()
{

 Serial.println("Data Received from Master Board");
 data = SPI_SlaveReceive();
  Serial.println(data, HEX);
 data = 0;

}

unsigned char SPI_SlaveReceive()
{
 while(!(SPSR & (1<<SPIF)));
 return SPDR;
}




Output from receiving code:
Code: [Select]

Data Received from Master Board
3B
Data Received from Master Board
3B
Data Received from Master Board
3B
Data Received from Master Board
3B




And now what should I do modification in the code so that I can send some data to master once I receive 0x3B from master.
I am trying like this at receiving(slave) side, it is receiving 0x3B from master but not able to send data to master
Code: [Select]

#include <SPI.h>
#include <stdio.h>
#include <avr/io.h>
#include <stdlib.h>

#define MOSI 11
#define MISO  12
#define SCK  13
#define SS 10
#define sss 9
int data = 0;
char buff[8];


void setup()
{
 pinMode(MOSI, INPUT);
 pinMode(MISO, OUTPUT);
 pinMode(SCK,INPUT);
 pinMode(SS,INPUT);
 pinMode(sss, OUTPUT);

 Serial.begin(9600);
 SPCR = 0x40;  // Enable SPI in slave mode
//  SPI.begin();
 delay(500);
 
}

void loop()
{
int xx;
 Serial.println("Data Received from Master Board");
 data = SPI_SlaveReceive();
 
 xx = data;
 
  Serial.println(data, HEX);
 data = 0;
 delay(20);
 if(xx == 59)
 {
   delay(600);
   void master_init();
   unsigned char send2();
   delay(600);
 }
}
 unsigned char send2(){
 digitalWrite(SS, LOW);
 WriteByte(16);
 digitalWrite(SS, HIGH);
 delay(600);}

unsigned char SPI_SlaveReceive()
{
 while(!(SPSR & (1<<SPIF)));
 return SPDR;
}
void master_init()
{
   pinMode(MOSI, OUTPUT);
 pinMode(MISO, INPUT);
 pinMode(SCK,OUTPUT);
 pinMode(SS,OUTPUT);
 pinMode(sss, OUTPUT);
 
}
void WriteByte(byte value) {
 SPDR = value;
 while (!(SPSR & (1<<SPIF))) ;
 return;
}

And at the master side I am doing like this but it is not able to receive the data
Code: [Select]


#include <SPI.h>// include the SPI library:

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:
#define sss 9
int mm =0;
unsigned char data1 = 0;

void setup() {
 
 pinMode (spidata, OUTPUT);// set the spi_data_pin as an output:
 
 SPI.begin();// initialize SPI:
 Serial.begin(9600);
}

void loop() {
    //for(mm=0; mm<23;mm++){
     digitalWrite(spidata,LOW);
     //Serial.println("I am writting on SPI");
     //Serial.println(mm, BIN);
     SPI.transfer(0x3b); //  send in the address and value via SPI:
    // SPI.transfer('IMU');
     
     digitalWrite(spidata,HIGH);// take the SS pin high to de-select the chip:
     delay(600);
     //digitalWrite(sss,LOW);
     
     
     unsigned char read1();
     delay(600);
     //digitalWrite(sss,HIGH);
     
    }
    unsigned char read1()
     {
       void slave_init();
     data1 = read_ready();
     
     Serial.println(data1, DEC);
     data1 = 0;
     
     delay(60);
     
     }
     
     
     unsigned char read_ready()
     {
       while(!(SPSR & (1<<SPIF)));
       return SPDR;
   
   }
  void slave_init()
  {
    SPCR = 0x40;
   pinMode(11, INPUT);
   pinMode(12, OUTPUT);
   pinMode(13, INPUT);
   pinMode(10, INPUT);
   delay(600);
   
  }

Kindly suggest me for the modification.

ranjeetray


That's a good point - SPI.transfer will work for both master and slave I think (master mode doesn't require the SPDR to be read, but transfer does this anyway).


Dear Sir

Thanks a lot for your kind support. Kindly go through the post  Reply #23 on: Today at 05:15:07 PM and please suggest for the modification on the code.


Thanks and Regards.

Nick Gammon

Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

ranjeetray



Kindly go through the post  Reply #23 ...


Kindly stop ignoring our suggestions.

Dear Sir

Where do you want me to use this SPI.transfer() function in my code, And I am not trying to avoid yours suggestion. Please guide me and help me out.


Thanks & Regards..

ranjeetray



Kindly go through the post  Reply #23 ...


Kindly stop ignoring our suggestions.


Respected Sir,

This code is able to send the data but not able to receive, what is wrong in this;

Code: [Select]



//send receive
#include <SPI.h>// include the SPI library:
#define SCK_PIN   13
#define MISO_PIN  12
#define MOSI_PIN  11
//#define SS_PIN    10
unsigned char receive_data(void);




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:

unsigned char rd = 0;

void SlaveInit(void) {
  // Set MISO output, all others input
  pinMode(SCK_PIN, INPUT);
  pinMode(MOSI_PIN, OUTPUT);
  pinMode(MISO_PIN, INPUT);
  pinMode(spidata, INPUT);
  Serial.begin(9600);

  // Enable SPI
  SPCR = B00101100;
     SPCR = (1<<SPE);
     //SPCR = 0x00;
   
}

void setup() {
 
   pinMode(SCK_PIN, OUTPUT);
  pinMode(MOSI_PIN, INPUT);
  pinMode(MISO_PIN, OUTPUT);
  pinMode(spidata, OUTPUT);
 
  //pinMode (spidata, OUTPUT);// set the spi_data_pin as an output:
 
  SPI.begin();// initialize SPI:
  Serial.begin(9600);
  //SPI.setBitOrder(LSBFIRST);
  //SPCR = 0x90;
}

void loop() {digitalWrite(spidata,LOW);
            SPI.transfer(0x3b); //  send in the address and value via SPI:
            digitalWrite(spidata,HIGH);
            delay(400);
           receive_data();
           
            }
   
   
    unsigned char read_data(void)
    {  //SPCR = 0x60;
      while(!(SPSR & (1<<SPIF)));
      return SPDR; }
   
    unsigned char receive_data(){
     
    pinMode(spidata, INPUT);
     SlaveInit();
     rd = read_data();
      Serial.println(rd, DEC);
      rd = 0;
      delay(400);
      return 0;
    }
     
     
     
     

ranjeetray


Quote
Even this code is working fine .

Then, what IS your problem?


Respected Sir,

Can we read/transmit here 16 bit data on Arduino board using SPI protocol. Will it generate 16 continuous clock signal.

Graynomad

The Arduino has an 8-bit SPI peripheral and therefore only transmits 8 bits at a time.

However you can just transmit two bytes in a row, the end result is the same.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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