Kinetis MicrocontrollersのトピックK66 SPI MISO Decay

K66 SPI MISO Decay

lfost — Wed, 13 Oct 2021 18:26:46 GMT

Working with a k66 micro. Noticed the spi miso line ends high then drifts low. The k64 does not do this. No software affects it. A pull up resistor fixes the decay/drift but is typically not done. Is this normal for a k66?

Re: K66 SPI MISO Decay

nxf77486 — Fri, 15 Oct 2021 14:34:01 GMT

Hello @lfost ,

Some followers leaves the line floating when he is not handling it. In these cases the recommendation is to configure a pull-up in the MISO line so that it does not float when the follower so not driving the line.

Re: K66 SPI MISO Decay

myke_predko — Fri, 15 Oct 2021 16:57:41 GMT

@lfost

If you're not using one of the SPI pin functions, you don't need to assign a pin to the function.

That's the easiest solution (with the next easiest one putting a pull up on it or tying the pin to GND the way you have) otherwise you'll probably see delays and other weirdness.