S32KのトピックRe: S32K3 LCU Two-channel multiplexer

S32K3 LCU Two-channel multiplexer

wuxianlong — Tue, 05 Jul 2022 02:41:45 GMT

Hi,friends

When I was learning LCU, I met a problem and I hope to get your help.
As i see it .
In Logic diagram ,if Sel = 0 ,Y == A. if Sel = 1, Y == B.
But,In Waveforms , when Sel = 1, Y != B. Why ?

Re: S32K3 LCU Two-channel multiplexer

PetrS — Thu, 07 Jul 2022 10:05:18 GMT

Hi,

it is explained in the last sentence of the Waveforms chapter...

Writes to SWEN and SWVALUE have immediate impact on LC outputs, whereas LC inputs require input synchronization to prevent metastability.

Synchronization is 2 LCU clocks as mentioned in the figure 257. So Y has value of A or B delayed by 2 clocks. SEL value also takes effect after 2 clocks while SWEN and SWVALUE immediately.

PetrS_0-1657188291302.png

BR, Petr

Re: S32K3 LCU Two-channel multiplexer

wuxianlong — Sat, 09 Jul 2022 05:41:57 GMT

Hi, PetrS

Thank you for your help.

BR,