PWM display for 16 bit value

[zumpitu]

i All

I have set up a PWM with a 16bit value duty cycle with a Period overflow of 3200 ....

when I start the simulation the duty cycle diagram have a strange behaviour, is working but de value is smaller that what should be.

I connected the board with a motor and looks is working fine , I do not understand if is something wrong on my code or if is a kind of bug.

I also made a super small file with only the PWM and a delay and I have the same result. If I use the 8 Bit value all looks good

I attached the file, I apologise for the Italian comments

[medelec35]

Hi zumpitu,
The period is the value required for 8bit PWM to have a duty of 100%
For 10bit PWM this value has to be x 4
So if period is 3200 for 100% duty:
For SetDuty8Bit = 3200
For SetDuty10Bit = 3200 x 4 = 12800

Martin

[zumpitu]

Hi medelec35

Ok I see, thank you , and actually it work on that way,

but is still think is strange because my board ( Nucleo F446RE ) have all 16 bit timer and 2 32bit with same resolution , so according the wiki

SetDutyCycle10Bit
PIC/AVR - Sets the full scale PWM duty cycle based on the current period setting.

If period = 255 then Duty of 512 is equal to 50%.


16-bit PICs have a 16-bit period range available.

If period = 65535 then Duty of 32768 is equal to 50%.

This is why I'm was confused


I also tried to use the Oscilloscope, but I still don't understand how to make it working, I'm going to do some research to how to use it , because looks very very useful.

[LeighM]

Hi zumpitu,
Yes, you are correct, there is a bug in the PWM simulation display, for ST ARM, I will have a look at fixing it

16-bit PICs have a 16-bit period range available.
If period = 65535 then Duty of 32768 is equal to 50%.

This is correct for ST ARM too.

Leigh

[zumpitu]

Hi LeighM


Then the function is working properly but is just the graphic that is not correct, Thank you for the info !


Nice to see that you are looking to fix it

[LeighM]

Hi,
This is now fixed and will go out with the next update, if it hasn't already.

[zumpitu]

Thank you this is really great !