TMS570LC4357: Halcogen example_epwm_adc.c

Chandra Sekhar N

Part Number: TMS570LC4357
Other Parts Discussed in Thread: HALCOGEN

I am working with Demo board TMS57LC43x HDK. I am trying to execute the HalcoGen example_epwm_adc.c. I have followed the steps mentioned in the example screen to configure HalcoGen and created the CCS project. I can see 50% duty cycle PWM pulse on B5. This is fine. But I do not observe the ADC notification happening with PWM configured trigger. I kept a break point in function ADC notification. Not sure what could be going wrong? Can you please guide me further what to check?

over 5 years ago

0 Miro over 5 years ago

TI__Mastermind 21425 points

Hello,

Start Of Conversion event is generated by EPWM but adcNotification() is called by ADC Event Group interrupt Handler when conversion ends. You should enable ADC1 Event interrupt in VIM (Channel 14). HALCoGen will generate ADC1 Group0 (Event Group) interrupt handler where adcNotification will be called.

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Thanks Miro for the reply. Do we have any way to catch Start of conversion event? I will try to enable the VIM and check the ADC1 interrupt event.

0 Chandra Sekhar N over 5 years ago in reply to Chandra Sekhar N

Intellectual 880 points

I have enabled ADC1 Event interrupt in VIM (Channel 14) in HalcoGen. I did not see continuous ADC conversions triggered from PWM. No hit of break point at ADC notification function too.

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

Would you try the attached project? I've test it and it works at my place.

Note: I moved adcNotification() in HL_notification.c

6354.example_epwm_adc_4357.zip

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Dear Miro, Sorry to say that the result is same with the attached code example. I can see only twice the code hit the break point at adcNotification function. By the way I did not connected any voltage source at ADC input pin. I believe the floating value shall not create any issue. Am I missing something? do you see the notification hit at each PWM execution?

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

Please change FIFO size of ADC1 Group Event to 1 (Tab ADC1 -> Tab ADC1 Group Event).

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Glad to see that this fix is perfectly working. Thanks for the assistance. As I have asked in one of my previous post, Is there a way to catch the start of ADC conversion trigger. As you mentioned, this event is associated with end of conversion.

0 Sunil Oak over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 49120 points

You can enable output of the AD1EXT_ENA signal on the MIBSPI3SOMI / AD1EXT_ENA / ECAP2 (V8) OR the MIBSPI5SOMI[3] / DMM_DATA[15] / I2C2_SCL / AD1EXT_ENA (G16) terminals (whichever is available/unused in your application). You can observe the AD1EXT_ENA signal. It corresponds with the start of sampling event of the ADC.

Regards, Sunil

0 Chandra Sekhar N over 5 years ago in reply to Sunil Oak

Intellectual 880 points

Hi Sunil. Thanks. I have one more question on the ADC1 Group 1 trigger selection from HalcoGen. The HW trigger function is understandable from the selection. For the SW trigger selection, the input is shown as SW trigger? Which SW trigger is to be used for triggering the ADC1 Group 1 trigger event and how to generate the event? can you please provide an example for this. I want to trigger for PWM counter value comparison. Again, the notification will be end of conversion I believe.

0 Chandra Sekhar N over 5 years ago in reply to Chandra Sekhar N

Intellectual 880 points

Hi Can some one answer my questions on ADC1 Group1 trigger selection?

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

A conversion in software triggered groups can be started just by writing the desired channels to the respective Channel-Select Registers. For example, in order to convert channels 0, 1, 2, and 3 in Group1 and channels 8, 9, 10, and 11 in Group2, the application just has to write 0x0000000F to ADG1SEL and 0x00000F00 to ADG2SEL. The ADC module will start by servicing the group that was triggered first, Group1 in this example.

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Hi,

I am well aware of grouping of ADC channels. My question about triggering those groups with HalcoGen configuration selection. Under the ADC1 Group 1 Trigger diagram, We have Hardware and Software selection. Hardware trigger path selection is clearly shown with Event and Edge selection. But the Software shown as only Software trigger. I want to know what is this Software trigger can be used to generate ADC1 Group 1 trigger, which enable me to get notification. How I can access the Software trigger.

Regards,

Chandra

0 Chandra Sekhar N over 5 years ago in reply to Chandra Sekhar N

Intellectual 880 points

OK Miro. I got it now reading your reply multiple times. The Software trigger is the ADC conversion register trigger. This will enable entire group conversion in single go. Am I correct?

Chandra

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

ADC Event Group can be only hardware triggered.

ADC Group 1 and ADC Group 2 operating mode control registers have an extra control bit: HW_TRIG. This bit configures the group to be hardware event-triggered instead of software-triggered, which is the default.

When software triggering is used (as mentioned in my previous post) for starting the conversion ( triggering the conversion ) the desired channels for sampling has to be written in respective Channel-Select Registers (Writing to Channel-Select Registers will trigger the conversion).

If HW triggering is used, writing the desired channels will not trigger the conversion. When a group is configured to be event-triggered, the group conversion starts when at least one channel is selected for conversion in this group, AND when the defined event trigger occurs.

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Thanks for the detailed information.

0 Sunil Oak over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 49120 points

This information is also documented clearly in the reference manual, in section titled "How to Start a Conversion". See 22.2.1.6 on page 854 of SPNU563a.

0 Chandra Sekhar N over 5 years ago in reply to Sunil Oak

Intellectual 880 points

Further I am working on this and observed that ADC conversion for 4 channels is consuming 7 uSec for one sample. For the motor control application this time is too high. How can I optimize the ADC conversion time? The HalcoGen settings are as shown.

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

Please take a look at this thread:

You can change Cycle Time and Sample time but take a look at this document about impact of impedance of your external circuitry:

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Hi, the question is, the conversion time is multiples of the number of channels grouped?

0 Miro over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 21425 points

Hello,

Please take a look at this thread:e2e.ti.com/.../58734

0 Chandra Sekhar N over 5 years ago in reply to Miro

Intellectual 880 points

Thanks for an encouraging information.

Now again on events with PWM, I want to generate two events. (1) On start of each PWM cycle. (2) at 50% of TBPRD value. For (1) I am using eTPWM Interrupt event, and for (2) want to use SOCB. I am able to generate the events as required only at 50% duty cycle. For all other value of duty cycle change, the SOCB trigger is changing the timing. Do we have a solution which can create reliable events.

Best Regards,

Chandra

0 Chandra Sekhar N over 5 years ago in reply to Chandra Sekhar N

Intellectual 880 points

Can some one reply to my above problem?

0 Sunil Oak over 5 years ago in reply to Chandra Sekhar N

TI__Mastermind 49120 points

Chandra,

This thread was already answered and closed. Can you create a new post with your latest question?

Regards, Sunil

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TMS570LC4357: Halcogen example_epwm_adc.c