I found this mode in the code generated by the S32DS: "EMIOS_PWM_IP_MODE_OPWM" see the first picture, but the S32DS does not have the option for this mode, see the second picture, how do I use the "EMIOS_PWM_IP_MODE_OPWM" mode?
S32K3X4 does not have OPWM mode, but you can use OPWMFMB or OPWMB, which can achieve pulse width modulation too.
Mode supported by eMIOS.
To explain in detail, because we need to use a dual sampling and dual update control strategy, we need to update the duty cycle value at the time of overflow in the upward and downward counts. However, what I understand is that the signal marked in green in the figure below ("Reload duty") can only automatically take effect at the time of overflow in the downward count (overflow in the downward count is a PWM end), and the software cannot intervene, so I cannot make the duty cycle take effect at the time of overflow in the upward count. This is the problem I am facing.
Looking forward to any suggestions from you.
or
For the OPWMCB mode, the duty cycle will only be performed on the first clock of the next cycle.
You can check whether the OPWMT mode meets your needs.
"the BS2→BS1 transfer occurs at every AS1 match" So it is still not possible to update the duty cycle twice in a PWM waveform (I have also verified that it is indeed not possible because one PWM cycle only matches AS1 once, so only BS2->BS1 once). Do you have any other ideas you can share with me? Double sampling and double updating is a very useful strategy in motor control, or you can push my question to technical support personnel familiar with motor control. Thank you again for your support
Hello,
S32K3 eMIOS doesn't support the Double sampling and double updating feature, but I think maybe we can use eMIOS+LCU to achieve that.
I drafted a example timing shown in the attached picture.
The idea is use the LCU combine two channels PWM to one PWM signal.
I got your inspiration, but I'm not very familiar with the triggering of the LCU, do you look at the picture of the scheme, I use the OPWMB mode, every time I update the A register to determine the duty cycle of the OPWMB, the value of the B register is irrelevant, but can I achieve the odd rising edge of CH1 to determine the high level of the LCU, and the even number of times of CH1 to determine the low level of the LCU?
I made a demo for your reference.
And this demo is based on the timing in the previous answer.
In summary:
The eMIOS module cannot implement "Double sampling and double updating" alone, but it can be implemented in combination with the LCU module. That is, you need three PWM outputs and the LCU module to implement "Double sampling and double updating", but this looks more complicated.
