TMS320F280049C: + POSMGR project example to read BISS-C encoder

Hello - unfortunately we do not have an example on the F28004x at this time.  

I'm asking this because I'm trying to use this example: " Read Position of BiSS-C Absolute Encoder - MATLAB & Simulink - MathWorks Italia", but for some reason it doesn't work 100% correct. When I receive the frames from the SPIB interface, the third one it seems to be stucked showing always the same bits. I tried to see the signals on a oscilloscope and I noticed that the clock pulses ( MA signal) are less than what I expected. Is possibile in some way to configure the number of clock pulses?

Marcello,

There should be a header file where you can define some of the encoder parameters. You will need to change the number of position bits. 

In TI's f2837xd example it looks like the following.  I'm assuming Mathworks didn't change it. 

I tried to find this header file in the CSS project generated by the Matlab embedded core tool, but I didn't find anything.

There is just a file named biss.syscfg, May I need to edit this one?

I'll reach out to Mathworks and see if they can give me some input.

I don't think the setting is in there. I've sent a message to mathworks for their guidance.

Hi Marcello,

Can you change the 'FIFO interrupt level(Rx)' to 3 instead of 2 and try? You can find this setting in model configuration parameter -> Hardware Implementation -> Target hardware resources -> SPI_B.

biss.syscfg file is used to create clb_config.c and clb_config.h using TI CCS which has the complete CLB tile configuration.

Thanks,

Aditya

Unfortunately nothing has change :(

Hi Marcello,

The example is also configured to read data from 26-bit encoder. So, it should work directly for you. When you say, " clock pulses (MA signal) are less than what I expected", how many clock pulses did you see?

Thanks,

Aditya

Yes its correct, the example is configured to read data from a 26 bit econdoer for this reason I'm weired out that it doesn't work. Anyway I don't remember the exact number of pulses, but they were more thant 20 and less than 26.

Hi Marcello,

THE SPI module is configured to read 3 words of data with each word corresponding to shift 12-bits of data. So, if you receive only 2 words, you will see 24 SPICLK cycles and if you receive 3 words you will receive 36 clock cycles. But all this data is combined to extract only 26-bit data which is of interest for us. Hence, I suggested the FIFO interrupt level to be as 3 instead of 2 as we will receive interrupt after we receive 3 words for SPI.

Can you check if you are receiving this correctly as explained above?

Regards,

Aditya

I tried to set the FIFO interrupt level to 3 instead of 2 but nothing has changed. Anyway you can see the MA CLK, SLO signal and and the words red by

Matlab in the pictures below. 

Hi Marcello,

Thanks for sharing the images and data. Can you contact MathWorks tech support so that we can take this issue forward and solve the problem you are facing?

Regards,

Aditya

I have just contacted and talked to the MathWorks tech support, I really hope that the problem will be resolved. :)

Looking forward to hearing it is resolved as well.  Thank you for your patience, Marcello.