TMS570LC4357: HET1 generates an wrong PWM frequency when the VCLK2 clock is not 75 MHz

Cherry Zhou

Part Number: TMS570LC4357

Hi team,

Here's an issue from the customer may need your help:

HET1-16 generates the correct PWM frequency when VCLK2 is clocked at 75 MHz, while HET1-16 will generate incorrect PWM frequencies when VLCK2 is clocked at 50 MHz and 37.5 MHz.

Configure the VCLK2 clock to 37.5 MHz as shown in the figure below:

Enable N2HET1-16 to generate a frequency of 1KHz:

Enable pins of N2HET1-16:

The PWM tested is as follows:

Could you help look into this case? Thanks.

Best Regards,

Cherry

over 1 year ago

0 jagadish gundavarapu over 1 year ago

TI__Guru 57600 points

Hi Cherry,

I started to work on your issue and will provide an update soon.

Thanks & regards,
Jagadish.

0 jagadish gundavarapu over 1 year ago in reply to jagadish gundavarapu

TI__Guru 57600 points

Hi Cherry,

I can see the issue you mentioned at my end, let me debug further to find root cause. I will provide an update as soon as possible.

Thanks & regards,
Jagadish.

0 Cherry Zhou over 1 year ago in reply to jagadish gundavarapu

TI__Mastermind 22235 points

Hi Jagadish,

Thanks for your support and expect the updates.

Thanks and regards,

Cherry

0 jagadish gundavarapu over 1 year ago in reply to Cherry Zhou

TI__Guru 57600 points

Hi Cherry,

This issue already observed in the past in below thread,

(+) TMS570LC4357: N2HET PWM period error - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

Here they found out the reason is due to the

The VCLK2 frequency must always be greater than or equal to the VCLK frequency. The VCLK2 frequency must be an integer multiple of the VCLK frequency。

Thanks & regards,

Jagadish.