Go Down

Topic: SPI interface with other board_AVR_ESK1100 or among Arduino itself (Read 12050 times) previous topic - next topic

ranjeetray


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


Thanks a lot Sir for your kind reply.

I have done like this only , I am sending SPI.transfer(0x3B); SPI.transfer(0x2C); together in a row, and I am happy that it is transmitting both the data and generating 16 clock cycles on Oscilloscope but Sir, between these two consecutive 8 bit data there is a gap or delay on the Oscilloscope. So, for implementation like IMU(ADIS16405) chip where we need to send 16 bit command, how it will work.
The gap/delay between these two 8 bit data will be considered as 0.

Please suggest something on this.

Thanks & Regards..... :-)

Nick Gammon

Quote
The gap/delay between these two 8 bit data will be considered as 0.


No it won't because the receiving device only clocks in bits on the clock pulses. There is no "clocked" gap.
Please post technical questions on the forum, not by personal message. Thanks!

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

Nick Gammon

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

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

ranjeetray


Quote
The gap/delay between these two 8 bit data will be considered as 0.


No it won't because the receiving device only clocks in bits on the clock pulses. There is no "clocked" gap.


Thanks a lot Sir, for your kind reply.


Thanks & Regards...  :-)

ranjeetray

#34
Sep 06, 2012, 12:40 pm Last Edit: Sep 06, 2012, 12:47 pm by ranjeetray Reason: 1

http://www.gammon.com.au/spi



Respected Sir


After receiving data as data[1] = Slave_receive(); data[2] = Slave_receive(); which are suppose 0x3b and 0x34, Can we concatenate this and display as 0x3b34 on Serial.println(data, HEX); is it possible to do this.

I am getting two separate data as 0x3b and 0x34 but want to display together as 0x3b34.

Can you please guide me how to do this.


Thanks and Regards...!!!

Graynomad

Serial.println((data[1] << 8 ) + data[2], HEX);

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

ranjeetray


Serial.println((data[1] << 8 ) + data[2], HEX);

______
Rob


Respected Sir


Thanks a Ton. it is working. You are mind blowing Sir.


Thanks & Regards...... :)

Graynomad

Rob Gray aka the GRAYnomad www.robgray.com

ranjeetray


Quote
The gap/delay between these two 8 bit data will be considered as 0.


No it won't because the receiving device only clocks in bits on the clock pulses. There is no "clocked" gap.



Respected Sir

Why this following code is not generating 16 clock cycle continuously. Here I am using two continuous SPI.transfre(); but it is not giving 16 clock cycle.

Code: [Select]


#include <SPI.h>


#define SCK_PIN   13
#define MISO_PIN  12
#define MOSI_PIN  11
#define SS_PIN    10

unsigned char data;
int array[6] = {0x0A04, 0x0107, 0x0E05, 0x0209, 0x0B08, 0x0507 }, ii;

void SlaveInit(void) {
  // Set MISO output, all others input
  pinMode(SCK_PIN, INPUT);
  pinMode(MOSI_PIN, INPUT);
  pinMode(MISO_PIN, OUTPUT);
  pinMode(SS_PIN, INPUT);

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

void setup(){ Serial.begin(9600);
            SPI.begin();
            //SPI.setDataMode(SPI_MODE2);
            //SPI.setBitOrder(LSBFIRST);
          }

void loop()
{
  unsigned char hg = 0;
  Serial.println("Data Received from Master Board");
  SlaveInit();
  data = SPI_SlaveReceive();
   Serial.println(data, HEX);
   hg = data;
   data = 0;
   if(hg == 0x3B)
   {
     Serial.println("Writting Data on SPI bus");
     pinMode(SS_PIN, OUTPUT);
     digitalWrite(SS_PIN, LOW);
     SPI.transfer(0x3b);
     SPI.transfer(0x2b);   
     digitalWrite(SS_PIN, HIGH);
     Serial.println();
     Serial.println("Sending Done");
    delay(10); 
   }

}

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



Nick Gammon


Why this following code is not generating 16 clock cycle continuously. Here I am using two continuous SPI.transfre(); but it is not giving 16 clock cycle.


Prove it. Where is your logic analyzer output?
Please post technical questions on the forum, not by personal message. Thanks!

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

Graynomad

Quote
but it is not giving 16 clock cycle.

How do you know that?

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

ranjeetray


Quote
but it is not giving 16 clock cycle.

How do you know that?

______
Rob


Respected Sir


I am seeing the output on Oscilloscope, Tektronix TDS2024C, 200MHz 2GS/s.



Thanks & Regards...  :-)

ranjeetray



Quote
but it is not giving 16 clock cycle.

How do you know that?

______
Rob


Respected Sir


I am seeing the output on Oscilloscope, Tektronix TDS2024C, 200MHz 2GS/s.



Thanks & Regards...  :-)

Respected Sir

With the following code Arduino board is not able to generate its own clock it takes another boards when connected with MISO, MOSI, CS and SCK.
I found that once SPI_SlaveReceive(); function is initialized it is not able to generate the clock, if I comment this function or send the data or use SPI.transfer(); before SPI_SlaveReceive(); then it is able to generate the clock.
What would be the reason and how to overcome this problem.






Code: [Select]

#include <SPI.h>


#define SCK_PIN   13
#define MISO_PIN  12
#define MOSI_PIN  11
#define SS_PIN    10

unsigned char data;
int array[10] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09 }, ii;

void SlaveInit(void) {
  // Set MISO output, all others input
  pinMode(SCK_PIN, INPUT);
  pinMode(MOSI_PIN, INPUT);
  pinMode(MISO_PIN, OUTPUT);
  pinMode(SS_PIN, INPUT);

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

void setup(){ Serial.begin(9600);
            SPI.begin();
          }

void loop()
{
  unsigned char hg = 0;
  Serial.println("Data Received from Master Board");
  SlaveInit();
  data = SPI_SlaveReceive();
   Serial.println(data, HEX);
   hg = data;
   data = 0;
   delay(1000);
 
   if(hg == 0x3D)
   {
     Serial.println("Writting Data on SPI bus");
     pinMode(SS_PIN, OUTPUT);
     digitalWrite(SS_PIN, LOW);
     delay(1000);
     for(ii=0;ii<10;ii++){
     SPI.transfer(array[ii]);
     Serial.println(array[ii], BIN);
       delay(1000);     
     }
     digitalWrite(SS_PIN, HIGH);
     delay(1000);
   Serial.println("Sending Done");
    delay(1000); 
   }

}

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




Thanks & Regards....   :-)

Nick Gammon

Quote
I found that once SPI_SlaveReceive(); function is initialized it is not able to generate the clock ...


I don't understand what you are saying here. The master generates the clock, not the slave.
Please post technical questions on the forum, not by personal message. Thanks!

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

ranjeetray


Quote
I found that once SPI_SlaveReceive(); function is initialized it is not able to generate the clock ...


I don't understand what you are saying here. The master generates the clock, not the slave.


Respected Sir

Actually once it receive a data in slave mode then SPI clock becomes dead from this board, I want that my both the board should work as master and both should receive the data and send the data. Can we do like this. Is multimaster concept is same as what I am trying to do. Please guide me Sir.


Thanks & Regards....  :-)

Go Up