SPI transfer config in Matlab

[dsp28x]

Hi, I'm new to SUB-20. I want to use the SUB-20 SPI interface to read from another SPI modul, Using SUB-20 tool works OK, even though its only read a byte. The problem is in MATLAB, how to configure so that the SUB-20 can read data via MATLAB setup.

Here is my configuration

/* Configure SPI */
sub_spi_config( hndl, SPI_ENABLE|SPI_CPOL_RISE|SPI_SMPL_SETUP|SPI_MSB_FIRST|SPI_CLK_4MHZ, 0 );

Matlab Configure SPI
if ~ sub20.SPI_SetConfig(sub20.SpiEnable + sub20.SpiCpolFall + ...
sub20.SpiSmplSetup + sub20.SpiMsbFirst + sub20.SpiClk_8MHz)
break;
end

Synopsis
int sub_spi_transfer( sub_handle hndl, char* out_buf, char* in_buf, int sz, int ss_config )
rc = sub_spi_transfer( hndl, out, 0, 10, SS_CONF(0,SS_LO) );

if ~ sub20.SPI_SetConfig(sub20.SpiEnable + sub20.SpiCpolFall + ...
sub20.SpiSmplSetup + sub20.SpiMsbFirst + sub20.SpiClk_8MHz)
break;
end

% Create .NET data array
Data = NET.createArray('System.Byte', TransferSize);

% Fill up the array with data bytes to be sent
Data.Set(6, hex2dec('a'));
Data.Set(7, hex2dec('b'));
Data.Set(8, hex2dec('c'));
Data.Set(9, hex2dec('d'));

if ~ sub20.SPI_Transfer_r(Data, 0, sub20.SpiSS_HHL)
break;

I hope to hear from you.
dsp

[serg]

Hi,
Have you initialized the TransferSize variable before executing this code? Please note that the TransferSize must be at least 10 in your case. All the rest looks good. We have a similar SPI sample code.

%---------------------------------
disp 'SUB-20 SPI sample. Configures SPI and exchanges data with SPI slave(SS=2)'

TransferSize = 3;

NET.addAssembly('C:\Program Files\SUB-20\bin\sub20dnc.dll');
sub20 = Xdimax.Sub20();

% simulate do { ... } while(0) loop
for k=0:0

% Open first available SUB-20 device
if ~ sub20.Open(0)
break;
end

% Set SPI configuration
if ~ sub20.SPI_SetConfig(sub20.SpiEnable + sub20.SpiCpolRise + ...
sub20.SpiSmplSetup + sub20.SpiMsbFirst + sub20.SpiClk_4MHz )
break;
end

% Create .NET data array
Data = NET.createArray('System.Byte', TransferSize);

% Fill up the array with data bytes to be sent
Data.Set(0, hex2dec('2a'));
Data.Set(1, hex2dec('2b'));
Data.Set(2, hex2dec('2c'));

% Exchange data with SPI slave(SS=2). SS signal stays high
if ~ sub20.SPI_Transfer(Data, 2, sub20.SpiSS_H)
break;
end

% Copy read data to the Matlab array
ReadData=zeros(1, TransferSize);
for i=1:TransferSize
ReadData(i)= Data.Get(i-1) ;
end

end

err = sub20.GetLastError();

% Close SUB-20 device
sub20.Close()

if err > 0
fprintf('Error %d\n', sub20.GetLastError() )
error('Error!')
end

%---------------------------------------------

Regards

[dsp28x]

Hi serg,

I've intialized the TransferSiZe to 10. but the question is if SPI modul is slave, is there any way to intialize my code in MATLAB, so that I can automatically retrieve my data.
The example code in matlab code the values are constants.

% Create .NET data array
Data = NET.createArray('System.Byte', TransferSize);

% Fill up the array with data bytes to be sent
Data.Set(0, hex2dec('2a'));
Data.Set(1, hex2dec('2b'));
Data.Set(2, hex2dec('2c'));

% Exchange data with SPI slave(SS=0). SS signal stays high
if ~ sub20.SPI_Transfer(Data, 0, sub20.SpiSS_HHL)
break;
end

I've also tried to setup spi_transfer like this:
sub20.SPI_config(0,LO)
sub20.SPI_Transfer( hndl, out, 0, 10, SS_CONF(0,SS_LO) );
But it doesn't work. If there is proper way to setup the Matlab code, I'll glad to hear you.

Regards

[xol]

Hi,
I'm not working with MATLAB but if you use SUB-20 as SPI slave you have to use another functions.
Take a look here:
http://www.xdimax.com/sub20/doc/HTML/spi_slave.htm

[serg]

Hi,

Xol is right. If you want to use the SUB-20 as a SPI slave device the config sequence is different .
1) Add the sub20.SpiSlave flag to the sub20.SPI_SetConfig call
2) Call the sub20.FIFO_SetConfig( sub20.SelectSpi )
3) Call either FIFO_Read or FIFO_Write methods

Regards

[dsp28x]

Hi xol

I've tried to read data via SPI slave mode. It reads reads the last byte (Eg. 1234 will return as 3412). By the way are spi_read() and fifo_Read() does not support in Matlab? Error:
No method 'SPI_Read' with matching signature found for class 'Xdimax.Sub20'.
Here is my code (in MATLAB) if I've done something wrong :

SpiDataToRead = 10;

NET.addAssembly('C:\Programmer\SUB-20\bin\sub20dnc.dll')
sub20 = Xdimax.Sub20();


% simulate do { ... } while(0) loop
for k=0:0

% Open first available SUB-20 device
if ~ sub20.Open(0)
break;
end

% Set SPI configuration as slave
if ~ sub20.SPI_SetConfig(sub20.SpiEnable + sub20.SpiSlave + sub20.SpiCpolRise + ...
sub20.SpiSmplSetup + sub20.SpiMsbFirst + sub20.SpiClk_8MHz)
break;
end


% Spi fifo configurations
if ~ sub20.FIFO_SetConfig(sub20.FifoSelectSpi);
break;
end

% Create .NET data array
Data = NET.createArray('System.Byte', SpiDataToRead);
Arr = NET.createArray('System.Byte', SpiDataToRead);

% Setup array to SPI MOSI
for i=0:(SpiDataToRead-1)
Arr.Set(i,1);
end

% SPI read
if ~ sub20.SPI_Read(Data, Arr)
break;
end

% Exchange data with SPI slave(SS=0). SS signal stays high
if ~ sub20.SPI_Transfer(Data, 0, sub20.SpiSS_H)
break;
end


% Copy read data to the Matlab array
ReadData=zeros(1, SpiDataToRead);
for i=1:SpiDataToRead
ReadData(i)= Data.Get(i-1);
end

%
end

err = sub20.GetLastError();

% Close SUB-20 device
sub20.Close()

if err > 0
fprintf('Error %d\n', sub20.GetLastError() )
error('Error!')
end
%--------------------------------------------------------------------------
Best reagrads

[xol]

I've tried to read data via SPI slave mode. It reads reads the last byte (Eg. 1234 will return as 3412).

This is well known big/little endiens. SPI works on byte level and does not care about it. Check how your SPI master sends it.