TMS320F280039C: ECAP counter variable in 32-bit

Wayne Huang

Genius 17125 points

Part Number: TMS320F280039C
Other Parts Discussed in Thread: C2000WARE

Dear Champs,

I am asking this for our customer.

In our C2000ware example,

C:\ti\c2000\C2000Ware_5_01_00_00\driverlib\f28003x\examples\ecap\ecap_ex2_capture_pwm.c

We use

volatile uint16_t cap2Count;
volatile uint16_t cap3Count;
volatile uint16_t cap4Count;

...

cap2Count = ECAP_getEventTimeStamp(myECAP0_BASE, ECAP_EVENT_2);
cap3Count = ECAP_getEventTimeStamp(myECAP0_BASE, ECAP_EVENT_3);
cap4Count = ECAP_getEventTimeStamp(myECAP0_BASE, ECAP_EVENT_4);

Questions:

Since ECAP counter is in 32-bit, shouldn't we use uint32_t rather than uint16_t to handle ECAP counter values?

For example, if the result is larger than 65536, what happens?

That is, we think we should define them in 32-bit.

volatile uint32_t cap2Count;
volatile uint32_t cap3Count;
volatile uint32_t cap4Count;

What do you think?

Wayne

over 2 years ago

+1 Ryan Ma over 2 years ago

TI__Mastermind 27736 points

Hi Wayne,

Yes you're correct, the driverlib returns a uint32_t from that function call. I have created a ticket for this to be updated in our next C2000ware release.

If the result is larger than 65535, the uint will wrap back around to 0.

Best,

Ryan Ma

0 Wayne Huang over 2 years ago in reply to Ryan Ma

TI__Genius 17125 points

Dear Ryan

Thank you for your confirmation.
in fact, the user found the problem when referring to this example to capture an external GPIO with longer time (ECAP count > 65536 count).

0 Ryan Ma over 2 years ago in reply to Wayne Huang

TI__Mastermind 27736 points

Hi Wayne,

You're welcome. Thank you for noting this and providing us with feedback.

Best,

Ryan Ma

C2000™︎ microcontrollers

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TMS320F280039C: ECAP counter variable in 32-bit