Using EEPROM with Digital Potentiometer

lordpakweet · December 13, 2021, 7:46am

Hey all,

I am having some issues with integrating my EEPROM and Digital Potentiometer together.

So, I have saved some values in my EEPROM and I have to extract it to control the position of my digital potentiometer. Here's my code:

#include <Wire.h>    
#include <SPI.h>
#define disk1 0x50    //Address of 24LC256 eeprom chip
const int slaveSelectPin = 10; 
int eeprom_data[6];
int temp=0;
void setup(void)
{
  Serial.begin(9600);
  Wire.begin();  
 
  unsigned int address = 0;

  Serial.print("Contents of EEPROM: ");
  //EEPROM contains 50,100,150,200,25,130
  for(int i=0; i<6; i++)
  {
    eeprom_data[i]=readEEPROM(disk1,i);
    Serial.print(eeprom_data[i]);
    Serial.print(" ");
  } 
  for (int j = 0; j < 6; j++) 
  {
    digitalPotWrite(j, eeprom_data[j]);
    Serial.print(j);
  }

}
 
void loop(){}
 
void writeEEPROM(int deviceaddress, unsigned int eeaddress, byte data ) 
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.write(data);
  Wire.endTransmission();
 
  delay(5);
}
 
int readEEPROM(int deviceaddress, unsigned int eeaddress ) 
{
  byte rdata = 0xFF;
 
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.endTransmission();
 
  Wire.requestFrom(deviceaddress,1);
 
  if (Wire.available()) rdata = Wire.read();
 
  return rdata;
}
void digitalPotWrite(int address, int value) 
{

  // take the SS pin low to select the chip:

  digitalWrite(slaveSelectPin, LOW);

  delay(100);

  //  send in the address and value via SPI:

  SPI.transfer(address);

  SPI.transfer(value);

  delay(100);

  // take the SS pin high to de-select the chip:

  digitalWrite(slaveSelectPin, HIGH);
}

I have successfully extracted the data from my EEPROM but when I passed the array (eeprom_data) to the digitalPotWrite function, the code just froze there and it does not run the for (int j = 0; j < 6; j++) loop. (Edit: this loop only runs once. I need it to run 6 times)

I am using a 24LC256 EEPROM and an AD5206 digital potentiometer.

Any advice is greatly appreciated. Thanks!

anon73444976 · December 13, 2021, 7:53am

Loop index j, but then uses k?

I can't see a k

lordpakweet · December 13, 2021, 7:55am

I made a typo in that. The problem still persists. I cannot run this loop.

anon73444976 · December 13, 2021, 7:55am

The compiler is good at spotting typos.
Show the code that compiles

lordpakweet · December 13, 2021, 7:58am

This is my updated code, without the typo. It does not have any compiler errors. When I uploaded it to the board, the loop with the digitalPotWrite function doesn't run.

#include <Wire.h>    
#include <SPI.h>
#define disk1 0x50    //Address of 24LC256 eeprom chip
const int slaveSelectPin = 10; 
int eeprom_data[6];
int temp=0;
void setup(void)
{
  Serial.begin(9600);
  Wire.begin();  
 
  unsigned int address = 0;

  Serial.print("Contents of EEPROM: ");
  //EEPROM contains 50,100,150,200,25,130
  for(int i=0; i<6; i++)
  {
    eeprom_data[i]=readEEPROM(disk1,i);
    Serial.print(eeprom_data[i]);
    Serial.print(" ");
  } 
  for (int j = 0; j < 6; j++) 
  {
    digitalPotWrite(j, eeprom_data[j]);
    Serial.print(j);
  }

}
 
void loop(){}
 
void writeEEPROM(int deviceaddress, unsigned int eeaddress, byte data ) 
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.write(data);
  Wire.endTransmission();
 
  delay(5);
}
 
int readEEPROM(int deviceaddress, unsigned int eeaddress ) 
{
  byte rdata = 0xFF;
 
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.endTransmission();
 
  Wire.requestFrom(deviceaddress,1);
 
  if (Wire.available()) rdata = Wire.read();
 
  return rdata;
}
void digitalPotWrite(int address, int value) 
{

  // take the SS pin low to select the chip:

  digitalWrite(slaveSelectPin, LOW);

  delay(100);

  //  send in the address and value via SPI:

  SPI.transfer(address);

  SPI.transfer(value);

  delay(100);

  // take the SS pin high to de-select the chip:

  digitalWrite(slaveSelectPin, HIGH);
}

red_car · December 13, 2021, 8:12am

Do yourself a favour and add some Serial.println statements where you think it's getting stuck... most valuable tool in your diagnostic box.

lordpakweet · December 13, 2021, 8:14am

I have added a Serial.print command in the loop to check if the loop is running. I have tried different methods but this loop still won't run.

for (int j = 0; j < 6; j++) 
  {
    digitalPotWrite(j, eeprom_data[j]);
    Serial.print(j);
  }

anon73444976 · December 13, 2021, 8:15am

Does the pot expect a single SPI transaction?

Edit: I notice you've edited your original post, so now my earlier comment makes no sense.
I'm out.

lordpakweet · December 13, 2021, 8:20am

I have checked the original code from the AD5206 sample (https://www.arduino.cc/en/Tutorial/LibraryExamples/DigitalPotControl).

It cycles through different channels and changes the position. I am doing the same here. But it doesn't run the mentioned loop. I can't figure out why.

red_car · December 13, 2021, 8:20am

Then add some more, lots more...... in digitalPotWrite

lordpakweet · December 13, 2021, 8:23am

Ok update to last, the loop only runs once which I find it extremely weird

red_car · December 13, 2021, 8:24am

Post latest code.
Post matching Serial output.

lordpakweet · December 13, 2021, 8:29am

Here's the latest code with the debugging lines:

#include <Wire.h>    
#include <SPI.h>
#define disk1 0x50    //Address of 24LC256 eeprom chip
const int slaveSelectPin = 10; 
int eeprom_data[6];
int temp=0;
void setup(void)
{
  Serial.begin(9600);
  Wire.begin();  
 
  unsigned int address = 0;

  Serial.print("Contents of EEPROM: ");
  //EEPROM contains 50,100,150,200,25,130
  for(int i=0; i<6; i++)
  {
    eeprom_data[i]=readEEPROM(disk1,i);
    Serial.print(eeprom_data[i]);
    Serial.print(" ");
  } 
  Serial.print("\n");
  Serial.print("Iteration ");
  for (int j = 0; j < 6; j++) 
  {
    Serial.print("\n");
    Serial.print(j);
    digitalPotWrite(j, eeprom_data[j]);
    
  }

}
 
void loop(){}
 
void writeEEPROM(int deviceaddress, unsigned int eeaddress, byte data ) 
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.write(data);
  Wire.endTransmission();
 
  delay(5);
}
 
int readEEPROM(int deviceaddress, unsigned int eeaddress ) 
{
  byte rdata = 0xFF;
 
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.endTransmission();
 
  Wire.requestFrom(deviceaddress,1);
 
  if (Wire.available()) rdata = Wire.read();
 
  return rdata;
}
void digitalPotWrite(int address, int value) 
{

  // take the SS pin low to select the chip:

  digitalWrite(slaveSelectPin, LOW);

  delay(100);

  //  send in the address and value via SPI:

  SPI.transfer(address);

  SPI.transfer(value);

  delay(100);

  // take the SS pin high to de-select the chip:

  digitalWrite(slaveSelectPin, HIGH);
}

Serial monitor output:

Hopefully, this helps! Thanks!

red_car · December 13, 2021, 9:01am

OK so it obviously never comes back from the first call... like I said... use Serial.println... LOTS OF THEM !!!! You are trying to figure out which bit is blocking...

#include <Wire.h>    
#include <SPI.h>
#define disk1 0x50    //Address of 24LC256 eeprom chip
const int slaveSelectPin = 10; 
int eeprom_data[6];
int temp=0;
void setup(void)
{
  Serial.begin(9600);
  Wire.begin();  
 
  unsigned int address = 0;

  Serial.print("Contents of EEPROM: ");
  //EEPROM contains 50,100,150,200,25,130
  for(int i=0; i<6; i++)
  {
    eeprom_data[i]=readEEPROM(disk1,i);
    Serial.print(eeprom_data[i]);
    Serial.print(" ");
  } 
  Serial.print("\n");
  Serial.print("Iteration ");
  for (int j = 0; j < 6; j++) 
  {
    Serial.print("\n");
    Serial.print(j);
    digitalPotWrite(j, eeprom_data[j]);
    
  }

}
 
void loop(){}
 
void writeEEPROM(int deviceaddress, unsigned int eeaddress, byte data ) 
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.write(data);
  Wire.endTransmission();
 
  delay(5);
}
 
int readEEPROM(int deviceaddress, unsigned int eeaddress ) 
{
  byte rdata = 0xFF;
 
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8));   // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.endTransmission();
 
  Wire.requestFrom(deviceaddress,1);
 
  if (Wire.available()) rdata = Wire.read();
 
  return rdata;
}
void digitalPotWrite(int address, int value) 
{

  // take the SS pin low to select the chip:
  Serial.println("Here 0");
  digitalWrite(slaveSelectPin, LOW);

  delay(100);
  Serial.println("Here 1");
  //  send in the address and value via SPI:

  SPI.transfer(address);
  Serial.println("Here 2");

  SPI.transfer(value);
  Serial.println("Here 3");

  delay(100);

  // take the SS pin high to de-select the chip:

  digitalWrite(slaveSelectPin, HIGH);
    Serial.println("Here 4");

}

lordpakweet · December 13, 2021, 9:06am

@red_car thanks for your suggestion. I have added in more stuff similar to what you have said but I still can't solve the problem.

I found out where it stopped (refer to comment in code). I have used your code for easy reference.

void digitalPotWrite(int address, int value) 
{

  // take the SS pin low to select the chip:
  Serial.println("Here 0");
  digitalWrite(slaveSelectPin, LOW);

  delay(100);
  Serial.println("Here 1");
  //  send in the address and value via SPI:

  SPI.transfer(address); //Stops here
  Serial.println("Here 2");

  SPI.transfer(value);
  Serial.println("Here 3");

  delay(100);

  // take the SS pin high to de-select the chip:

  digitalWrite(slaveSelectPin, HIGH);
    Serial.println("Here 4");

}

Here's the corresponding output of the serial monitor:

Hope you will be able to give me more insights.

red_car · December 13, 2021, 9:19am

SPI.begin();

in setup.

lordpakweet · December 13, 2021, 9:23am

Thanks so much!! Can't believe I missed out on that line.

red_car · December 13, 2021, 9:30am

Remember Serial.println... and a quick google search on "spi.transfer never returns"... you aren't the first, and won't be the last

sterretje · December 13, 2021, 11:24am

@lordpakweet, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project See About the Installation & Troubleshooting category.

system · June 11, 2022, 11:24am

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.

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Using EEPROM with Digital Potentiometer

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