CCS/TMS320F28379D: Reading counter value on timer interrupt not producing expected results

Christo Labuschagne1

Tool/software: Code Composer Studio

Good day.

We need 4 quadrature encoders on our device, so I created my own in CLB. I have two GPIO's coming in driving two FSM's, one for forward and one for backward. These then feed into a LUT with an OR between them. The output of the LUT triggers the counter and add or subtract is determined by if FSM for forward is high. I then have a system timer that triggers every 10 ms and I read the value of counter using CLB_getRegister(CLB1_BASE, CLB_REG_CTR_C0);. I have a watch expression that keeps an eye on the value.

This is basics and I was sure it worked at some point. Now I'm having an issue where the counter value jumps around. I've simplified the test forcing the counter to add by hard coding the mode1 to 1, and only trigger if the encoder drives forward (This is one clock cycle pulses). It counts up fora moment then the value goes jumps to a new value, including a value that is lower than what it was. How can it be lower if there is no reset event set and if the mode1 is set to 1?

Thank you for the feedback

over 6 years ago

0 Peter Galicki over 6 years ago

TI__Expert 8105 points

Hi Cristo,

I need to contact CLB experts for this question, should be getting back to you shortly\

Regards,

PEter

0 Peter Galicki over 6 years ago in reply to Peter Galicki

TI__Expert 8105 points

Christo,

From the description of your symptoms (CLB counter jumps around) it seems to me that the first thing to check would be that the period of the CLB counter is not smaller than the period of the system timer. The simplest way to check this would be to reduce the system timer period by a lot and see if the CLB counter values stop jumping around.

Regards,

Peter

0 Christo Labuschagne1 over 6 years ago in reply to Peter Galicki

Intellectual 290 points

Hi Peter.

Thank you for your reply. I have made the timeout 100 ms and 1 s and in both cases, the problem persists.

Please find attached the files used for the project. If you want to run it in a sim you will need to change FSM_0.e1 to LUT_0.out as that is how I generate the quadrature encoding for a sim. Just to confirm that the sim seems to work correctly.

The setup is done with the same encoder running to EQEP and to GPIO 0 and 1 so I can try and compare the two encoders.

meerkat_cam_controller.zip

0 Nima Eskandari over 5 years ago in reply to Christo Labuschagne1

TI__Guru 52220 points

Instead of reading the Counter value through the CPU interface, create a signal in the TILE, pass it as event signal to the HLC, in the HLC use the PUSH instruction to send the counter value into the FIFO, then generate a CLB interrupt.

In the CLB interrupt, read the CLB HLC FIFO and get the counter value.

Nima

0 Nima Eskandari over 5 years ago in reply to Nima Eskandari

TI__Guru 52220 points

Did you try the method above?

Nima

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CCS/TMS320F28379D: Reading counter value on timer interrupt not producing expected results