topic Can I use Capture component to read frequency in Processor Expert Software

Can I use Capture component to read frequency

vijenad — Tue, 25 Aug 2015 13:36:56 GMT

IDE - Kinetis Design Studio

Processor Expert

Evaluation board - TRK-KEA128

1. Can I use capture component to read the frequency

2. Frequency will be in kHz

3. As I am already using PPG module to generate PWM, will there be any conflict if I use capture_LDD component to capture frequency

4. Is there any other component in process expert to capture frequency or Which is the preferred component in processor expert to read frequency

5. First step is to understand component functionality/working, accuracy and resolution will be followed later.

6. I guess, PWT can be used only to measure Pulse Width, but not frequency - Am I correct ? or can we use it to measure frequency too?

Message was edited by: Vijeendra N I was able to read frequency with capture_LDD bean

Re: Can I use Capture component to read frequency

marek_neuzil — Tue, 13 Oct 2015 08:11:59 GMT

Hello,

If you use PPG_LDD component you cannot use the Capture_LDD at the same timer (different channel of the same timer). The PPG driver change the timer modulo register and it will impact the Capture_LDD range (overflow). Sharing of one timer by PPG_LDD and Capture_LDD is not supported in Processor Expert. You must use one timer for PPG_LDD and another timer for Capture_LDD.

Capture_LDD can be used for measuring frequency, see for example discussion capture_LDD-result

If you use PWT to measure time between two rising (or falling) edges you measure period of the signal (duration of one pulse) and you can compute the frequency (frequency = 1 / period). You can also find details in the application note http://www.freescale.com/files/microcontrollers/doc/app_note/AN4839.pdf?fsrch=1&sr=1&pageNum=1

Best Regards,

Marek Neuzil