TM4C123GH6PZ: QEI not working at high temp

Pragnesh Patel

Part Number: TM4C123GH6PZ

I am using QEI with Renishaw quadrature encoder. I am also measuring pulses and voltage level through oscilloscope.

Everything seems working well until CPU temperature reaches 62-63 degC. Above this temperature somewhere A,B and index pulses are missed and CPU never gets the index pulse. (If it gets, then it should reset the counter.) Scope shows voltage level seems matching at normal temperature v/s elevated temperature.

Is any body has similar observation?

over 6 years ago

0 Bob Crosby over 6 years ago

TI__Guru 72500 points

What voltage levels are you getting?

0 cb1_mobile over 6 years ago

Guru 117850 points

"Which" quad encoder from Renishaw? We have several - none suffer (nor does "4C123" @ that/near temp.) as you report...

And - as always - how many such boards have you tested - and what percentage "behave in this "flawed" manner?" (so important - most always "missed" by vendor)

0 Robert Adsett over 6 years ago

Guru 27665 points

And to add to the questions, how are you measuring CPU temperature? Have you done a sanity check on that?

Robert

0 Pragnesh Patel over 6 years ago in reply to Bob Crosby

Intellectual 935 points

0.1V (low) and 5.0V (High).

Renishaw RLC2IC readhead and MR49 ring generating quadrature encoder.

Just one unit tested so far. Testing another one. Will update the post with results.

0 Pragnesh Patel over 6 years ago in reply to Pragnesh Patel

Intellectual 935 points

We are measuring CPU temperature using CPU internal temperature sensor as well as by thermocouple connected to data logger.

0 cb1_mobile over 6 years ago in reply to Pragnesh Patel

Guru 117850 points

And the result of that "thermocouple" reading is...?

We did have the MR49 - did not note your issue. We later moved to the superior "Orbis" Mag. Encoder (BR10DCA14B12BD00) working w/Mag. Actuator (BA080AA01AA00). We await your testing/reporting of (multiple) others...

0 Pragnesh Patel over 6 years ago in reply to cb1_mobile

Intellectual 935 points

Thanks. Will update with more results.

0 Pragnesh Patel over 6 years ago in reply to Pragnesh Patel

Intellectual 935 points

It turned out that after precision alignment between Renishaw read head and Renishaw magnetic ring, the arrangement seems working at +55 degC ambient. It was thermal expansion issue and read head was moving out of magnetic ring's comfort zone.

0 Robert Adsett over 6 years ago in reply to Pragnesh Patel

Guru 27665 points

Thanks, a like is deserved for following up.

Robert

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TM4C123GH6PZ: QEI not working at high temp