NetBurner Community Forum

Has anyone here worked with the quadrature input on the eTPU of the MOD5234?

I have a panel mounted rotary encoder that generates 30 pulse per rev and I can see the input pins on the device clocking as I turn the knob.

The issue I have is in setting up and reading the eTPU for QD input.

I use the following to init the eTPU for QD input.

fs_etpu_qd_init(GPIO_ENC_A,
0,
0,
FS_ETPU_QD_PRIM_SEC,
FS_ETPU_PRIORITY_MIDDLE,
0,
FS_ETPU_TCR1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

I then call this function to read the value and it hangs from this point and never returns.

Count = fs_etpu_qd_get_pc(GPIO_ENC_A);

Any ideas what else I need to do to get this to work as there are no examples of using the eTPU or quadrature inputs?

Cheers,
Dave...

OK, been doing some debugging and getting something strange in this function call.

int24_t fs_etpu_qd_get_pc( uint8_t channel_primary)
{
return(fs_etpu_get_chan_local_24s(channel_primary, FS_ETPU_QD_PC_OFFSET));
}

The call to fs_etpu_get_chan_local_24s does return, but when this function goes to return it hangs!!

I thought it was a stack issue and increased the size in the task that this call is made to 1024 in size but still same issue.

Need to delve a little more into the stack before and after this call.!!

Dave...

I can probably help. We created the tools that generated teh frescale libraries.

Walter@bytecraft.com

Send me more details for the question or post them here.

Thanks
w..

Hi Walter,

I sorted the crash. I made the usual mistake with pointers and passed in the value instead of a pointer to it. Oops.

Still not getting any counts but that might be the configuration. Maybe you can help with this. This is what I have for config. The encoder is 30ppr.

fs_etpu_qd_init(GPIO_ENC_A,
0,
0,
FS_ETPU_QD_PRIM_SEC,
FS_ETPU_PRIORITY_MIDDLE,
0,
FS_ETPU_TCR1,
0, 0, 0, 0, 0,
0x733333,
0x8CCCCC, 0, 0, 0,
1000,
30);

fs_etpu_qd_set_pc(GPIO_ENC_A, 0);

fs_etpu_qd_disable(GPIO_ENC_A, 0, 0, 0);

fs_etpu_qd_enable(GPIO_ENC_A,
0,
0,
FS_ETPU_QD_PRIM_SEC,
FS_ETPU_PRIORITY_MIDDLE);

fs_etpu_qd_set_slow_mode(GPIO_ENC_A);


GPIO_ENC_A is set to 8 and I am using channels 8 & 9 for the inputs. I can see them toggling with the scope.

Cheers,
Dave...

It would appear that the Quadrature decoder is not included with the NNDK set that gets loaded into the eTPU.

There is another set for this but I see that it does not support UART and I need both UART and QD in the same set.!!


Off to do some more digging.

Dave...

It's working.

I finally figured out that the standard build does not include quadrature as part of the eTPU so I went to the Freescale website and created my own custom eTPU build and now it works!!

Excellent!

Dave...