I2C

[rmb]

Hi

 

I would like to communicate with MCP4725 DAC from Papiio DUO through I2C.

Is it possible to use I2C library or it could work only with WII Chuck?

 

Thank you

 

rmb.

[Jack Gassett]

Hello rmb,

 

The I2C library should work with any I2C device, the Wii Chuck has its own separate library that uses I2C.

 

The Wii Chuck library actually gives you a good idea of how to use the I2C library:

https://github.com/GadgetFactory/DesignLab_Examples/blob/master/libraries/WiiChuck/WiiChuck.cpp

 

Jack.

[rmb]

Jack, thank you for your answer.

I started from simple task however no luck yet.

I added I2C to wishbone 9 and attached signals to pins Arduino_7 and Arduino_6 like in provided example.

For sketch I used next modified code (originally provided for Wire arduino library):

#include <i2c.h>

#define DAC_ADDR 0x60

int lookup = 0; // index

int mysin[512] =

{

  2048, 2073, 2098, 2123, 2148, 2174, 2199, 2224,

…

  1847, 1872, 1897, 1922, 1948, 1973, 1998, 2023

};

void setup() {

  I2C.begin(100000);

  I2C.enable();  

  }

void loop() {

  I2C.start(DAC_ADDR,0);

  I2C.tx(64); 

  I2C.tx(mysin[lookup] >> 4); 

  I2C.tx((mysin[lookup] & 15) << 4); 

  I2C.stop();

 

 

  lookup = (lookup + 1) & 511;

}

Unfortunately I don’t  see any activity at Pins 6 an 7.

I would like to ask some questions which could help me moving forward:

How need I declare in sketch that I attach I2C to wishbone 9 at ZPUino soft processor?

What is second argument in function I2C.start?

Thank you

rmb

[alvieboy]

 

Unfortunately I don’t  see any activity at Pins 6 an 7.

 

Hi, are your pins at logic '1' or '0' ? Do you have external pullups ?

 

 

How need I declare in sketch that I attach I2C to wishbone 9 at ZPUino soft processor?

 

No need, it will detect the slot (you should see that when you start your sketch).

 

 

What is second argument in function I2C.start?

 

If I recall well, it's how I2C handles read vs. writes (direction). See "I2C Device Addressing" here: http://www.robot-electronics.co.uk/acatalog/I2C_Tutorial.html

[Jack Gassett]

If you bring up a serial terminal at 115200 and press reset on the Papilio you should see it say that it detects the I2C device and the wishbone slot it is connected to.

 

Jack.

[rmb]

Gents, thank you for answers.

A half issue was that probably I made some mistake when I modified ZPUino Vanilla soft processor (I attached I2C symbol to wishbone 9, remove Arduino pins 6 an 7 from WING_AL, extend I2C pins by wires, create markers to that and rename ports as Arduino_7 and Arduino_6 ). When I uploaded this to FPGA and test it with blinked pin6 sketch the pin6 change his value. It means something wrong with my modified soft processor.

When I loaded circuit from of WIIChuck sketch and uploaded my I2C sketch, I see activity on pins 6 and 7. However another half issue remains unsolved. DAC does not change his output value.

I suppose it is not connect with next behavior, but my question why it is happened:

I saw drift of first clock pulse between 5us to 8us on oscilloscope when processor send each third byte to DAC (from 4 bytes send within loop()).

Thank you.

rmb

[rmb]

I found solution for second part of issue.

I need to add at least 10us delay at loop().

It give me the Sin with f~4.5Hz what is compatible with arduino uno.

rmb.