Revision 120 breaks PwmOut on FRDM-K64F

[infinnovation-dev]

(Copied as requested from https://developer.mbed.org/users/mbed_official/code/mbed/issues/36 )

With revision 120 of mbed, PwmOut on a FRDM-K64F appears to be broken i.e no output is seen.

A demonstration program is at https://developer.mbed.org/users/infinnovation/code/pwm_regression/

On FRDM-K64F, connect LED+330R between PTD0 (J2.6) and GND (J2.3)

With revision 119 of mbed, LED is lit as expected.

With revision 120 of mbed, the LED is not lit.

[0xc0170]

cc @mmahadevan108

[mmahadevan108]

Thanks, I will take a look and update.

[infinnovation-dev]

So, I added some code to examine the FTM registers and found several differences:

FTM3_	v119	v120	Comments
SC	8e	8e
CNT	2958	2e2
MOD	493d	493d
C0SC	a8	a0	ELSnB:ELSnA=0 => revert pin to GPIO etc.
C0V	15f8	15f8
C1SC	0	0
C1V	0	0
C2SC	0	0
C2V	0	0
C3SC	0	0
C3V	0	0
C4SC	0	0
C4V	0	0
C5SC	0	0
C5V	0	0
C6SC	0	0
C6V	0	0
C7SC	0	0
C7V	0	0
CNTIN	0	0
STATUS	1	1
MODE	4	5	FTMEN=1: enable FTM-specific registers
SYNC	0	8	SYNCHOM=1: outmask updated by PWM synch
OUTINIT	0	0
OUTMASK	0	0
COMBINE	0	20202020	SYNCENn=1
DEADTIME	0	40	DTPS=1: (bit ignored if higher bit clear)
EXTTRIG	0	0
POL	0	0
FMS	0	0
FILTER	0	0
FLTCTRL	0	0
QDCTRL	0	0
CONF	3	3
FLTPOL	0	0
SYNCONF	0	1fb4	SWSOC,SWINVC,SWWRBUF,SWRSTCNT,SYNCMODE,SWOC,INVC,CNTINC
INVCTRL	0	0
SWOCTRL	0	0
PWMLOAD	0	0

The killer seems to be C0SC where both ELSnA and ELSnB are zero "Pin not used for FTM--revert the channel pin to general purpose I/O or other peripheral control".

I poked 0xa8 into 0x400b900c and, sure enough, my LED came on.

[mmahadevan108]

At patch with updated FTM, TPM drivers have been submitted to ARM.

[infinnovation-dev]

OK, thanks.

[infinnovation-dev]

I can confirm that this issue is fixed in revision 121.