2 replies to this topic

[alexandrosroidis]

Hi to all,

I need to connect this board from ams to netduino

http://www.ams.com/e...8A-EK-AB-STM1.0

It has the as5048a magnetic encoder ic which is spi compatible.

the ic datasheet is here

http://www.ams.com/e...Sensors/AS5048A

 

so i connect everything as i should on the netduino

my code is

 

using System;
using System.Collections;
using System.Threading;
using Microsoft.SPOT;
using System.Globalization;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
using System.IO.Ports;
using System.Text;

namespace spi_encoders
{
  public class Program
  {

  public static void Main()
  {
SPI.Configuration as5048a = new Microsoft.SPOT.Hardware.SPI.Configuration
  (SecretLabs.NETMF.Hardware.Netduino.Pins.GPIO_PIN_D5, false, 100, 100, false, true, 10000,
  SecretLabs.NETMF.Hardware.Netduino.SPI_Devices.SPI1);

  ushort[] command_buffer = { 0x3FFF};//0x3fff is the read command
 
  ushort[] angle_buffer = new ushort[1];//the ic returns 16bit reply to the read command
 
  ushort result;
  double angle;
  SPI spibus = new SPI(as5048a);
  while (true)
  {
 
  spibus.WriteRead(command_buffer, angle_buffer);
 
 
Debug.Print("Data from chip trial:" +" "+ angle_buffer[0].ToString());

 

  }
  }

 
  }
}
 

without the magnet around i getting nonsense result from the chip

 

like

Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576
Data from chip trial: 24576

if i put the magnet near and start rotating it i get:

Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8335
Data from chip trial: 8336
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41104
Data from chip trial: 41106
Data from chip trial: 8338
Data from chip trial: 8339
Data from chip trial: 41107
Data from chip trial: 57493
Data from chip trial: 24725
Data from chip trial: 8342
Data from chip trial: 41112
Data from chip trial: 8345
Data from chip trial: 41115
Data from chip trial: 8348
Data from chip trial: 41118
Data from chip trial: 8351
Data from chip trial: 41121
Data from chip trial: 8356
Data from chip trial: 8357
Data from chip trial: 57512
Data from chip trial: 57512
Data from chip trial: 57514
Data from chip trial: 24747
Data from chip trial: 57515
Data from chip trial: 57515
Data from chip trial: 57515
Data from chip trial: 57515
Data from chip trial: 57515
Data from chip trial: 57514
Data from chip trial: 24746
Data from chip trial: 24744
Data from chip trial: 41127

 

I am very frustrated because i bought the netduino for this purpose and it seems unable to do what i want

this is the second mag encoder i bought the first was from avago and it was ssi

 

Can anyone help me out

Is something wrong with my code

 

Alexandros

 

[ziggurat29]

is it the correct SPI mode?  the data sheet seems to suggest mode 1 (q.v. S 4.2.1), but I think (!) you set mode 0, as per the final two booleans  in your SPI.Configuration.  I think they should be false, false for mode 1.

 

After that I would look at the command itself, and the exact meaning of WriteRead.  SPI as you know is a shift register, and there is always input while there is output, though you might discard it.  I would imagine that 0x3fff has an associated input that is discarded, and the subsequent transfer (maybe using output 0x0000 NOP as per S 4.2.7?) has the input that is the angle (returned from the 0x3fff).

 

Please just take that as a suggestion -- I have never worked with this particular device, and also have little hands-on experience with the NP2 SPI implementation (though I done it with other controllers).

 

Also, if you have an oscilloscope, you might want to hook that up and crank down your clock rate to see what's really going on.  (This was recently invaluable for me in debugging an i2c problem; I would have spent forever guessing).

[alexandrosroidis]

Solved

Thanks for the help ziggurat