TMS570LC4357: Generate complementary pwm outputs with dead band using N2HET

Veena Saluja

Prodigy 140 points

Part Number: TMS570LC4357
Other Parts Discussed in Thread: HALCOGEN

Hi,

Is there an example program, using N2HET for generating complementary pwm outputs with dead band for tms570lc4357?

7 days ago

0 jagadish gundavarapu 5 days ago

TI__Guru* 77806 points

Hi Veena,

Please refer below thread once:

(+) TMS570LS1224: EPWM not able to produce - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

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Thanks & regards,
Jagadish.

0 Veena Saluja 5 days ago in reply to jagadish gundavarapu

Prodigy 140 points

Hi Jagdish,

We cannot use the epwm module as we need to generate 24 pwm outputs (both high side and low side). TMS570 has 7xePWM peripherals each with complementary outputs - 14 PWM outputs which does not suffice. Hence we are considering using N2HET for generating the pwm signals. Do you have any example code to generate complementary out puts using HET IDE? There is a mention about an example in this thread on the Ti forum by Anthony but I couldn't find it:

ite2e.ti.com/.../rm4-n2het-generate-negative-pwm-on-pin-n-1

0 jagadish gundavarapu 4 days ago in reply to Veena Saluja

TI__Guru* 77806 points

Hi Veena,

The below thread will be helpful for your requirement, please refer it.

(+) LAUNCHXL-TMS57004: Output of Complementary Pairs of PWM Signals - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

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Thanks & Regards,
Jagadish.

0 Veena Saluja 19 hours ago in reply to jagadish gundavarapu

Prodigy 140 points

Hi Jagdish,

Thanks for the link.

I have used the het file ( pwm1p.het) in the above link that you have provided in the HET IDE and generated the c, h file. I tried to integrate the header and c file in my CCS project and execute on a TMS570LC437 HDK. I have configured HETPFR[15:8] to 0x7, and HETXOR to 0xC000; I am not getting expected outputs on the scope:

a) The frequency of PWMs is not 10KHz.

b) I am seeing high and low pulses on HET1 Pin 29 and HET Pin 31.

c) I am seeing lot more high pulses which doesn't look right as below.

d) The het file in the link provided is for HET Clk configured to 80MHz for TMS57004 , where as I have VCLK2 setting as 75MHz in Halcogen for TMS570LC4357. I need to modify the HET file but didn't quite understand why cntmax_lr is done as below:

cntmax .equ 0FFFFFFFFh
cntmax_lr .equ (cntmax / 128)

Please can I get some help on understanding the het file so that it can be adapted for the VCLK2 setting for the TMS570LC4357 I am using.

There are about 60 instructions in het file? Are they all needed?