topic Re: KSDK2.0 FTM PWM setup bug in Kinetis Software Development Kit

KSDK2.0 FTM PWM setup bug

mtbrewster — Wed, 03 Feb 2016 23:39:34 GMT

It appears there is a bug in the KSDK2.0 driver for the FTM in the FTM_SetupPwm function. It has to do with specifying the output type, the ELSnB:ELSnA settings in the CnSC register. The input parameter is ftm_chnl_pwm_signal_param_t *chnlParams. The level field in that struct is an enum of type ftm_pwm_level_select_t which has possible values of:

typedef enum _ftm_pwm_level_select

{

kFTM_NoPwmSignal = 0U, /*!< No PWM output on pin */

kFTM_LowTrue, /*!< Low true pulses */

kFTM_HighTrue /*!< High true pulses */

} ftm_pwm_level_select_t;

The error is in the following line of code (which is used in both branches of if/else):

/* Setup the active level */

reg |= (FTM_CnSC_ELSA(chnlParams->level) | FTM_CnSC_ELSB(chnlParams->level));

this shifts level by 2 and masks it with 4 and ORs that with level shifted by 3 anded with 8.

This does not give the appropriate ELSnB:ELSnA settings.

Re: KSDK2.0 FTM PWM setup bug

Jmart — Thu, 04 Feb 2016 12:13:35 GMT

Mike -

I've forwarded on your finding to the FTM developer.

Regards

Re: KSDK2.0 FTM PWM setup bug

bluetiger9 — Sat, 25 Jun 2016 20:48:57 GMT

This is still not fixed.

Ugly fix for who needs high-true PWM:

            /* Setup the active level */
            reg |= chnlParams->level == kFTM_HighTrue ? 8
            : (FTM_CnSC_ELSA(chnlParams->level) | FTM_CnSC_ELSB(chnlParams->level));

Re: KSDK2.0 FTM PWM setup bug

manfredschnell — Mon, 18 Jul 2016 08:48:57 GMT

Hi Jason,

I need a PWM with kFTM_HighTrue, too.

Did you get any reaction from FTM developer Team?

In the meantime I use Attilas workaround.

Best regards.

Manfred