topic Re: S32DS PA SDK 2.9.0 eMIOS OPWMB channel cannot be driven from OPWFMB timebase in S32 SDK

S32DS PA SDK 2.9.0 eMIOS OPWMB channel cannot be driven from OPWFMB timebase

dan_teodorescu — Fri, 10 May 2019 22:21:17 GMT

Hello,

The current implementation of S32DS PA SDK 2.9.0 does not support the configuration of an eMIOS OPWMB channel with a timebase channel configured to be in OPWFMB mode. It only supports a timebase channel configured in MCB mode.

Our application requirement is for two eMIOS channels generating opposite-polarity signals, with dead-time in between, as follows:

               ________           ________                       _____
TB_CHAN : ____|        |_________|        |__________|     
          ___            ______              _______
AUX_CHAN:    |__________|      |____________|       |________

One of the channels is assigned to a BCD eMIOS channel, and the other belongs to the same eMIOS group; ie. one of the channels has to function as common timebase and pwm output.

The current driver seems to require three eMIOS channels, one functioning as an MCB timebase and two functioning as pwm outputs. This seems to be a limitation of the eMIOS pwm driver implementation and not of the eMIOS peripheral itself. Therefore, please update the driver such that:

The OPWMB function will accept a timebase channel operating in OPWFMB mode.
There is a way to initialize the leading and trailing edge placement for the OPWMB mode.

Attached you can see a partial implementation of the proposed solution.

Thank you,

Dan

Re: S32DS PA SDK 2.9.0 eMIOS OPWMB channel cannot be driven from OPWFMB timebase

PetrS — Tue, 14 May 2019 09:25:13 GMT

Hi,

I guess the SDK driver is following the RM and it states "An external counter driven in MCB Up mode must
be selected from one of the counter buses." for OPWMB mode.

Anyway OPWFMB seems to be functional too as counter bus.

BR, Petr

Re: S32DS PA SDK 2.9.0 eMIOS OPWMB channel cannot be driven from OPWFMB timebase

dan_teodorescu — Fri, 17 May 2019 17:17:17 GMT

Hi Petr,

You are correct, the counter must be in MCB mode (such that it counts from 1 ... A1) and count UP only, otherwise the behavior is unexpected or undefined. I would assume that the counter part of the UC configured as OPWFMB would operate as MCB UP mode, at least the RM description of MCB and OPWFMB seems identical with respect to counter control. If this is the case, should the documentation be updated? This will free up an eMIOS channel in our application.

Thank you,

Dan