6 replies to this topic

[PeterB]

I have a DFRobot I2C LCD display that I can easily drive with the Arduino (a library is available). I have no idea of how or where to start to make something similar for the Netduino.

I have the I2CBus code and now I need to work out how the I2C bus works before I can attempt to build a driver for the display module.

Looking for any suggestions about how I should tackle the problem.

Thanks,

[phantomtypist]

http://microliquidcr...l.codeplex.com/

[PeterB]

http://microliquidcr...l.codeplex.com/

Thanks for the link.

I downloaded the zip file and was able to run the HelloWorld_I2C solution. Running as per the download didn't work, that is it just ran to completion and no display. So I then changed the address to 0x27 (as per the DFRobot) and at that point it threw an exception in the I2CBus WriteRead function included below.

public void WriteRead(I2CDevice.Configuration Config, byte[] WriteBuffer, byte[] ReadBuffer, int TimeOut)
        {
            ThrowIfDisposed();
            lock(this.Device)
            {
                this.Device.Config = Config;
                I2CDevice.I2CTransaction[] xacts = new I2CDevice.I2CTransaction[] {
                    I2CDevice.CreateWriteTransaction(WriteBuffer),
                    I2CDevice.CreateReadTransaction(ReadBuffer)
                };

                // I2CDevice.Execute returns the total number of bytes
                // transfered in BOTH directions for all transactions
                int byteCount = this.Device.Execute(xacts, TimeOut);
                if(byteCount < (WriteBuffer.Length + ReadBuffer.Length))
                    throw new System.IO.IOException();
            }
        }

I am well and truly out of my comfort zone with this, it is very low level and I just don't have the wherewithall to understand this at present.

Looking at the local variables I can see that bytecount is 1 and the length of the WriteBuffer and ReadBuffer is 1 each so a total of 2, which is why it throws the exception. I have no idea as to what is really going on.

Before somebody suggest it, I have put pull-up resistors on the I2C bus (4k7).

Any further suggestions greatly appreciated (including suitable books as I am new to C#, .NET and uC).

Thanks

[Anthony Glenwright]

Did you have any luck with this? I am in the same situation as you.

[Anthony Glenwright]

Just a followup, I solved my problem (same as the original poster) by including 4.7k pull-up resistors on sca and scl. Or, more to the point, wiring them in correctly.

[travisbeard]

Thanks for the link.

I downloaded the zip file and was able to run the HelloWorld_I2C solution. Running as per the download didn't work, that is it just ran to completion and no display. So I then changed the address to 0x27 (as per the DFRobot) and at that point it threw an exception in the I2CBus WriteRead function included below.

public void WriteRead(I2CDevice.Configuration Config, byte[] WriteBuffer, byte[] ReadBuffer, int TimeOut)
        {
            ThrowIfDisposed();
            lock(this.Device)
            {
                this.Device.Config = Config;
                I2CDevice.I2CTransaction[] xacts = new I2CDevice.I2CTransaction[] {
                    I2CDevice.CreateWriteTransaction(WriteBuffer),
                    I2CDevice.CreateReadTransaction(ReadBuffer)
                };

                // I2CDevice.Execute returns the total number of bytes
                // transfered in BOTH directions for all transactions
                int byteCount = this.Device.Execute(xacts, TimeOut);
                if(byteCount < (WriteBuffer.Length + ReadBuffer.Length))
                    throw new System.IO.IOException();
            }
        }

I am well and truly out of my comfort zone with this, it is very low level and I just don't have the wherewithall to understand this at present.

Looking at the local variables I can see that bytecount is 1 and the length of the WriteBuffer and ReadBuffer is 1 each so a total of 2, which is why it throws the exception. I have no idea as to what is really going on.

Before somebody suggest it, I have put pull-up resistors on the I2C bus (4k7).

Any further suggestions greatly appreciated (including suitable books as I am new to C#, .NET and uC).

Thanks

Did you ever get this to work?

[travisbeard]

Just a followup, I solved my problem (same as the original poster) by including 4.7k pull-up resistors on sca and scl. Or, more to the point, wiring them in correctly.

Where did you change the address?