TMS320F28335: getting input value of ECAP module

Nicola Cimminiello

Part Number: TMS320F28335

Hello.

We have to develop an application for the speed control of a BLDC motor using HALL sensors.
For the speed measurement we use the ECAP module of the MCU (TMS320F28335), to estimate the period of the signal produced by the HALL sensors. We would also acquire the state assumed by the signal produced by HALL sensors (high or low) to generate the correct activation sequence of the bridge. We cannot understand in which register of the ECAP the status of the input is saved.

over 3 years ago

0 Frank Ankapong over 3 years ago

TI__Mastermind 28275 points

Hi Nicola,

The ECAP results are stored in the CAP1 to CAP4 registers. Please read through the ECAP chapter in the TRM if you haven't already.

0 Nicola Cimminiello over 3 years ago in reply to Frank Ankapong

Prodigy 50 points

Hi Frank.
Thanks a lot for your reply. I referred to SPRU807B.
If I understand correctly in these registers the value of the counter is saved.
Instead I can't understand in which register I can read the status of the input (if it is high or low). That is, read the status of the GPIO at the same time. it's possible?

0 Frank Ankapong over 3 years ago in reply to Nicola Cimminiello

TI__Mastermind 28275 points

Hi Nicola,

Yes, you can. The status of the GPIO is reflected in the GPxDAT register where 'x' here stands for 'A', 'B', etc. By the way, unless your signal frequency is low, GPxDAT will be changing too rapidly for you to read in software and still leave some CPU processing bandwidth. GPxDAT is meant more for checking static signals. Let us know if this is not clear.

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TMS320F28335: getting input value of ECAP module