Regarding Min ADC trigger count used in MC9S12ZVML128_BLDC_Sensorless sample code

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Regarding Min ADC trigger count used in MC9S12ZVML128_BLDC_Sensorless sample code

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Contributor V

Hello Team,

I am using MC9S12ZVML128_BLDC_Sensorless sample code for reference.

As per my understanding, the delays filled in the PTU trigger list are in terms of bus clock cycle.

Please confirm the understanding is correct or not.

As per datasheet, in 1.13.3.1 Motor Control Loop Overview point below note is given,

NOTE
In the PTU there is time window after the reload event assertion before the
first trigger is permitted. This time can be up to 10 bus cycles.
Subsequent triggers also require a load time of 6 bus clock cycles (one
trigger generator enabled) or 10 bus clock cycles (both trigger generators
enabled). This defines the minimal spacing between triggers without
causing a PTU trigger generator timing error.
In the ADC there is 10 bus cycle maximum time window after the reload
event assertion to access the first ADC command from the list. In this
window the ADC conversion can not be started. If the measurement is
control loop related these delays are negligible due to much larger delays in
the PWM-GDU-feedback loop.

As per above note, the first trigger should be set as >=10 bus clock cycle.

In sample code, the minimum first trigger is MIN_ADC_TRIGGER_FIRST = 8, for fBUS=12.5MHz

As per my understanding, MIN_ADC_TRIGGER_FIRST  should be >=10 bus clock

Please confirm the understanding.

But the SW behaviour is ok with the MIN_ADC_TRIGGER_FIRST = 8.

So, i want to know the reason , how SW is working correctly even if the MIN_ADC_TRIGGER_FIRST  is not as per the datasheet.

Request you to share the answers of above points.

Thanks in advance.

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3 Replies

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NXP TechSupport
NXP TechSupport

Hello pratibhasurabhi,

This specification in the RM has changed.
Below is a snippet from RM rev 1.5.
It seems that the demo hasn’t been updated.

pastedImage_2.png

BR, Daniel

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Contributor V

Hi Daniel,

Thanks for the quick reply.

The note I have mentioned above is from RM Rev 2.13. We are referring the latest version.

The note you have mentioned is from Rev 1.5.

Please let me know, which note should be used.

Thanks in advance.

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NXP TechSupport
NXP TechSupport

Hi Pratibha,

Please use the latest version of the RM, rev 2.13.

Thank you,

BR, Daniel

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