Kinetis Design Studioのトピックlong delay between chars when using SPI(FRDM-K64F)

long delay between chars when using SPI(FRDM-K64F)

lingqian — Thu, 25 Jun 2015 03:24:26 GMT

Hi there,

Has anyone met a problem when setting SPI delays (delay between chars) in Processor Expert?

My project is sending some data to a DAC via SPI and I used PE to do the settings. When the clock rate is around 1MHz, everything works fine and I can set the delay between chars to around 1.44us. However, when I increase the clock rate to a higher frequency, say 10MHz, and remain the delay between chars to 1.44us, the delay I get from logic analyzer becomes 5us.

I didn't change any code or settings except the clock rate, so I am really confused about this situation.

Anyone has any idea about this problem?

Thanks,

Ling

Re: long delay between chars when using SPI(FRDM-K64F)

Carlos_Mendoza — Fri, 26 Jun 2015 00:07:18 GMT

Hi Ling Q,

Please take a look to the recommendations made on the following post to avoid this delay between SPI transmissions:

Re: Long ~30uS delay between SPI byte transmissions in fsl_dspi during call to DSPI_DRV_MasterTransferBlocking(), what c…

Hope it helps!

Best Regards,

Carlos Mendoza

Technical Support Engineer

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Re: long delay between chars when using SPI(FRDM-K64F)

lingqian — Mon, 29 Jun 2015 01:22:41 GMT

Hi Carlos Mendoza,

Thanks for your quick reply.

I increased the core frequency of MK24FN1M0VLL12 to 120MHz using the first method in FRDM-K64F at Maximum Speed of 120 MHz | MCU on Eclipse and then my problem solved.

Thanks again.

Regards,

Ling