3 replies to this topic

[freds]

I have a PowerOne power supply that I am trying to interface with and it looks like uses a protocol that might not be supported.

Fragment from the manual is:

6.1 How to Read a byte
1) "Start condition" from Master
2) Master sends "Device address" with "write attribute"
3) "Acknowledge" from Slave device (FNP1500/1800)
4) Master sends "EEPROM address"
5) "Acknowledge" from Slave device (FNP1500/1800)
6) Master sends "Inversed EEPROM address"
7) "Acknowledge" from Slave device (FNP1500/1800)
8) "Repeated start" from Master (Sr/S)
9) Master sends "Device address" with "read attribute"
10) "Acknowledge" from Slave device (FNP1500/1800)
11) Slave sends "Data byte"
12) "Acknowledge" from Master (power management system)
13) Slave sends "Inversed Data byte"
14 "Not Acknowledge" from Master (power management system)
15) "Stop condition" from Master



I haven't previously seen an example that mentions inverse address and data on the I2C bus.

Suggestions on how to talk to this device?

I am trying to do this with the 4.2.0 RC5 firmware.

PowerOne I2C Programmers Manual

[CW2]

You'd have to use special I2C methods with internalAddress parameter to handle repeated start condition. The inverse address/data are not related to I2C protocol, it seems to be the device's data corruption detection mechanism. I don't have the device to verify the code, but something like the following should work:

...

static I2CDevice.I2CWriteTransaction CreateReadTransaction(byte[] buffer,
  uint internalAddress, byte internalAddressSize)
{
  // TODO: paste from http://forums.netduino.com/index.php?showtopic=944
}
  
public static void Main()
{
  // TODO: Slave address (does not include the R/W bit), clock rate
  I2CDevice device = new I2CDevice(new I2CDevice.Configuration(<<slaveAddress>>, 100));

  // TODO: The address to read from
  byte address = 0x00;

  var data = new byte[2];
  var readTransaction = CreateReadTransaction(data, (uint)((address << 8) | (~address & 0xFF)), 2);

  if(device.Execute(new I2CDevice.I2CTransaction[] { readTransaction }, 1000) > 0)
  {
    var dataByte = data[0];
    var dataInv  = data[1];
    if((dataByte ^ dataInv) != 0xFF)
    {
      // TODO: Data corrupted ?
    }
  }
}

Also, don't forget the pull-up resistors on I2C signal lines.

[freds]

Thank again CW2. I pasted in the code at the link and it is throwing an error for FieldInfo and BindingFlags. Is there a reference and using statement also required?

[freds]

Is there a reference and using statement also required?

I found it in another post; need to add a "using System.Reflection;" to get it to compile.