TMS320F28379S: PWM i/p signal decode query

Hello Ian,

The eCAP IP uses an input routed through the crossbar architecture. The input X-bar can be configured to route a GPIO pin to another peripheral. To see what each Input X-bar can be connected to, refer to table 8-1 on page 1065 of the technical reference manual. You can refer to this page in C2000 Academy for more information on the GPIO X-bar setup https://dev.ti.com/tirex/explore/node?node=ASYnY0SDpLPftmMS07lvqA__jEBbtmC__LATEST. You can also look at eCAP examples in the C2000Ware directory C2000Ware_4_01_00_00/driverlib/f2837xs/examples/cpu1/ecap.

Best regards,

Omer Amir

Hi Omer, thanks for the reply. I've seen this and its still not exactly clear which GPIO ports have the eCAP feature? Do GPIO21 and GPIO22 have eCAP?

Also one more question....

I'm trying to use a system block in Matlab to set GPIO o/ps which has worked fine in the past, but I keep getting the following error:-

I want to use GPIO/55/56/57/58 as a Mux i/p, but as soon as I uncomment each line I get an error?

Strange I dont get an error with the GPIO16 command?

Any help would be most appreciated...

Regards

Ian

Hi Ian,

To answer your first question, any GPIO can be used for eCAP if it's not already being used by another peripheral. The only restriction is that it must be routed through the correct input X-bar, since the eCAP peripheral uses input X-bar as the input.

For your second question, looking at the technical reference manual, table 7-112 on page 1007 shows the GPIO data registers. GPACLEAR for the F2837xS only clears the registers from GPIO0 to GPIO31 (indicated in the parentheses). To modify GPIO32 through GPIO63, use GPBCLEAR instead.

Let me know if you have further questions,

Omer Amir

Hi Omer,

Many thanks and the GPIOB ports are now working well.

Regarding the the eCAP function, its good to know that any GPIO port can use the eCAP peripheral, although I'm not sure how I access this in the Simulink model? If I look in the GPIO block where I want to use the eCAP function, the only options is the choice of which GPIO port is required:-

There is an eCAP block but I cant see how you specify which GPIO port is required:-

Is there an example of how to use this?

Regards

Ian

Hi Santosh, many thanks will take a look. Just have another h/w ques regarding the GPIO.

I'm have trouble getting the GPIOB to work through a Simulink System Outputs Function Declaration. I have five of these blocks with different GPIO set to select a MUX (GPIO55/56/57/58) and this changes on each tick and then repeats. i also use GPIO16 as an Enable and this is working fine but GPIO55/56/57/58 seem to always Low. Can you see anything wrong with this code?

Regards

Ian

Ian,

Omer is looking into the issue and will respond by tomorrow.

Thanks & Regards,

Santosh

Hi Ian,

It looks like you're only setting GPIO55 in this code, is that what you're expecting? Is the output for GPIO55 not set to 1? Looking at the exit code, the other pins are cleared so they should remain low.

Best regards,

Omer Amir

Hi Omer, Yes that's correct. Looking at the GPIO pins 55/56/57/58 with a scope they are just permanently low all the time. I was expecting the pins to toggle between "1111" and "0001" but they are just always low. GPIO16 toggles correctly between "0" and "1" as expected.

Regards

Ian

Hi Ian,

Do you know what you initialized the GPIO mux selections as for each of those pins? Looking at table 7-7 on page 836 of the technical reference manual, those pins may be assigned to other peripherals by default instead of as a GPIO pin. Depending on the peripheral it is muxed for, there could be restrictions on setting or clearing a pin.

Best regards,

Omer Amir

Hi Omer, the GPIO 55/56/57/58 pins are just being used with an external mux so are just being used as std individual digital o/ps. Shouldn't really be anything complicated and just changing the GPIO pattern to select a different mux channel as required...

Regards

Ian

Hi Ian,

Okay, do you mind sending me the initialization code so I can verify it with the TRM? Just as a sanity check to make sure I don't miss something.

Best regards,

Omer Amir

Yes sure, but probably will have to send you the whole simulink model, but how do I do that?

I'm not sure, I think you should ask MathWorks about how to do this, I am not familiar with Simulink.