S32k144 PWM duty cycle v/s Voltage

[Gargi2021]

Hi Team,

I am checking voltage across PTD15 when i am increasing duty counts from 0-32768 with 500 difference.

I observed that when count is 500, the voltage between PTD15 and GND is 4.91 and when count is 32768, Voltage is 0.728. it means when count is increasing, voltage is decreasing from maximum. but it should be like when count increasing, voltage should also increase.

could you please help in figuring out, why voltage is coming opposite to counts.

I am checking for this condition:

for (dutyCycle = 0; dutyCycle < 32768; dutyCycle += 500)
{
FTM_DRV_UpdatePwmChannel(INST_FLEXTIMER_PWM_1,
flexTimer_pwm_1_IndependentChannelsConfig[0].hwChannelId,
FTM_PWM_UPDATE_IN_TICKS, (uint16_t)dutyCycle,
0U,
true);
delayCycles(1);

Thanks,

Gargi

[PetrS]

Hi,

depends on polarity selected, try to change a polarity

BR, Petr

[Gargi2021]

Hi Petr,

Thanks for your reply.

when i am checking PWM on FTM PTD15 PIN. i made table for expected voltage range and actual voltage. which is shown below. 

pin voltage calculated(expected)	Pin voltage actual
0.99	1.97
1.32	2.4
1.485	2.61
1.65	2.83
1.98	3.26
2.805	4.33
2.97	4.54
3.3	4.97

on maximum period the max voltage is coming 4.97v,but i t should come 3.3.

can you please suggest me how i can set this voltage to 3.3v.

Thanks

[PetrS]

Hi,

probably MCU is powered by 5V. Check power supply selection jumper on the EVB.

BR, Petr