First off I should point out I’m totally new to electronics - I’m a C# developer by trade and just wanted to have a mess around. Anyway, I’ve bought a Panda II and this http://www.sparkfun.com/products/9810.
After looking around and playing a bit, I’ve wired the VIN to the 3V3,GND to ground and SLC and SDA to their respective pins (all straight into the board - well via a breadboard). I’ve confirmed there’s a circut by adding an LED on ground which works fine. The problem is I can’t seem to read any data back (or indeed write any). Here’s my code, I was wondering if someone could check my logic and wiring
public static void Main()
{
// create I2C object with address 0x18 (as per datasheet)
I2CDevice.Configuration con = new I2CDevice.Configuration(0x18, 400);
I2CDevice i2c = new I2CDevice(con);
// create transactions
I2CDevice.I2CTransaction[] xActions = new I2CDevice.I2CTransaction[2];
byte[] CTRL_REG1_A = new byte[] { 0x20, 0x27 };
byte[] CTRL_REG4_A = new byte[] { 0x23, 0x40 };
// create write buffer (we need one byte)
xActions[0] = I2CDevice.CreateWriteTransaction(CTRL_REG1_A);
xActions[1] = I2CDevice.CreateWriteTransaction(CTRL_REG4_A);
int exeResult = i2c.Execute(xActions, 1000);
if (exeResult == 0)
{
Debug.Print("Unable to init I2C device at 0x18");
return;
}
else
{
Debug.Print("I2C device initialized");
}
}
I’m always getting zero returned from the initial write transaction. Has anyone got any ideas please? Any help would be much appreciated.
Hi, thanks for the reply - I didn’t include the read transaction as I kept getting 0 returned from the write transaction - is this normal? I have just tried the I2C scanner posted previously but it found nothing unfortunately but here’s the full code:
public static void Main()
{
// create I2C object with address 0x18 (as per datasheet)
byte address = 0x18;
I2CDevice.Configuration con = new I2CDevice.Configuration(address, 100);
I2CDevice i2c = new I2CDevice(con);
// create transactions
I2CDevice.I2CTransaction[] xActions = new I2CDevice.I2CTransaction[2];
byte[] CTRL_REG1_A = new byte[] { 0x20, 0x27 };
byte[] CTRL_REG4_A = new byte[] { 0x23, 0x40 };
// create write buffer (we need one byte)
xActions[0] = I2CDevice.CreateWriteTransaction(CTRL_REG1_A);
xActions[1] = I2CDevice.CreateWriteTransaction(CTRL_REG4_A);
int exeResult = i2c.Execute(xActions, 1000);
if (exeResult == 0)
{
Debug.Print("Unable to init I2C device at 0x18");
return;
}
else
{
Debug.Print("I2C device initialized");
}
if (exeResult > 0)
{
Debug.Print("Trying " + address.ToString());
try
{
byte[] buffer = new byte[6];
buffer[0] = ReadIC2Register(i2c, 0x28);//read OUT_X_L_A (MSB)
buffer[1] = ReadIC2Register(i2c, 0x29);//read OUT_X_H_A (LSB)
buffer[2] = ReadIC2Register(i2c, 0x2A);//read OUT_Y_L_A (MSB)
buffer[3] = ReadIC2Register(i2c, 0x2B);//read OUT_Y_H_A (LSB)
buffer[4] = ReadIC2Register(i2c, 0x2C);//read OUT_Z_L_A (MSB)
buffer[5] = ReadIC2Register(i2c, 0x2D);//read OUT_Z_H_A (LSB)
int Ax = (int)(buffer[0] << 8) + buffer[1];
int Ay = (int)(buffer[2] << 8) + buffer[3];
int Az = (int)(buffer[4] << 8) + buffer[5];
Debug.Print("[" + Ax + "," + Ay + "," + Az + "]");
Thread.Sleep(100);
}
catch (Exception ex)
{
Debug.Print("Address: " + address.ToString() + " threw an exception");
}
}
}
public static byte ReadIC2Register(I2CDevice device, byte register)
{
byte[] write = new byte[] { register };
byte[] read = new byte[1];
I2CDevice.I2CTransaction[] readValues = new I2CDevice.I2CTransaction[] {
I2CDevice.CreateWriteTransaction(write),
I2CDevice.CreateReadTransaction(read)
};
int result = device.Execute(readValues, 1000);
return (byte)read[0];
}
}
This part has I2C pulled up to 1.8V. If you are always open collector, then you are probably OK (depending on what Panda sees as a logic 1) but if you have ever driven the I2C lines at 3.3V (during config, possibly), then you might have hurt the tiny board.
