MCP4131 with 8 - bit

Question

I am using MCP4131 with 7 - bit ( 0 - 127 ). Datasheet said that, it can work bit 7 and 8 bit and i definetly need to use it with 8 bit ( 0 - 255 ). Here is my code below;

#include <SPI.h>
byte address = 0x00;
int CS= 10;
void setup()
{
pinMode (CS, OUTPUT);
SPI.begin();

}
void loop()
{
digitalPotWrite(50);
}

int digitalPotWrite(int value)
{
digitalWrite(CS, LOW);
SPI.transfer(address);
SPI.transfer(value);
digitalWrite(CS, HIGH);
}

This is 7 bit code, to make it 8 bit, What should i change in the code ? Or what i need to do ?

Thank You Best Regards

Answer 1

From page 85 of the datasheet:

You can see that the 7-bit and 8-bit options are different devices. So MCP4131 is 7-bit only. It seems you need MCP4151.

Answer 2

This depends a lot on what is written in the datasheet on how to use it with the 8-bit feature. However, from your code it looks like you are storing the value in an integer and then writing that. Changing from int to unsigned int should work in this scenario but still a lot depends on what is written in the datasheet. It would be better if you clearly specify what is written in the datasheet regarding the use of 8-bit and 7-bit feature.