topic 回复： S32K3 LPCMP module Latency issues in S32K

S32K3 LPCMP module Latency issues

yinq — Wed, 26 Apr 2023 09:58:38 GMT

Hi,

I have encountered some problem of S32K3 , LPCMP module.

Which position may Tper appear in A, B, C, D, and indicate the number of Tper in this position?

Re: S32K3 LPCMP module Latency issues

PetrS — Thu, 27 Apr 2023 12:26:56 GMT

Hi,

there will be 2 Tper clock synchronization in the Window function (point B) and ((CCR1[FILT_CNT] x CCR1[FILT_PER]) + 1) x Tper clock for the Filter function (point D).

BR, Petr

Re: S32K3 LPCMP module Latency issues

zhanguiyang — Thu, 04 May 2023 08:57:48 GMT

How to handle the cross clock domain transition from window function to filter when using mode # 7?

回复： S32K3 LPCMP module Latency issues

zhanguiyang — Fri, 05 May 2023 01:06:47 GMT

How to handle the cross clock domain transition from window function to filter when using mode # 4A? Because in # 4A mode, the signal input to the filter is asynchronous with the filter clock window/sample.

回复： S32K3 LPCMP module Latency issues

zhanguiyang — Fri, 05 May 2023 01:10:18 GMT

回复： S32K3 LPCMP module Latency issues

PetrS — Fri, 05 May 2023 11:59:20 GMT

Hi,

If CCR1[SAMPLE_EN] is set to 1, the low-pass filter samples COUTA on each positive transition of the sample/window input. Window signal must be of minimum 4 bus cycle pulse for window mode to function. The output state of the filter changes when all the consecutive CCR1[FILT_CNT] samples agree that the output value has changed.

BR, Petr

回复： S32K3 LPCMP module Latency issues

zhanguiyang — Sun, 07 May 2023 03:48:25 GMT

In 4A mode, such as filt_ cnt=5,couta is output by the bus clock.but,when couta go in filter, the clock of the filter at this time is asynchronous window/sample signal. The first sampling count of couta by window/sample may have metastable state,How to solve this problem？

回复： S32K3 LPCMP module Latency issues

PetrS — Wed, 10 May 2023 11:51:16 GMT

Hi,

in this mode, the path from the analog inputs to COUTA is combinational (unclocked). COUTA is then input to Filter and COUT is sampled signal. A first sample will always happen at uncertain time and can be from 0 to period of sampling signal. This cannot be influenced anyhow.

BR, Petr

回复： S32K3 LPCMP module Latency issues

zhanguiyang — Fri, 19 May 2023 09:05:27 GMT

When CCR1[SAMPLE_EN]=1, the window/sample signal acts as the clock of the filter, asynchronously with the bus clock?

If they are asynchronous, can window/sample signals count against COUTA directly?

回复： S32K3 LPCMP module Latency issues

PetrS — Tue, 23 May 2023 07:59:45 GMT

Hi,

If CCR1[SAMPLE_EN] is set to 1, at positive transition of the sample/window signal COUTA is sampled and filter counts specifies the number of consecutive samples that must agree before the comparator output filter accepts the sample as a new valid output state.

BR, Petr

回复： S32K3 LPCMP module Latency issues

zhanguiyang — Fri, 26 May 2023 03:44:53 GMT

So,is the working clock of the filter a bus clock? window_sample signal is not the working clock of the filter?

回复： S32K3 LPCMP module Latency issues

PetrS — Wed, 31 May 2023 10:16:43 GMT

Hi,

this is a feedback I got from Apps team.

When CCR1[SAMPLE_EN]=1, the window/sample signal acts as the clock of the filter, asynchronously with the bus clock?

Yes

If they are asynchronous, can window/sample signals count against COUTA directly?

I can understand your mean. But you can refer the attachments which include the detail of filter, sample and window.

So, is the working clock of the filter a bus clock? Window_sample signal is not the working clock of the filter?

The LPCMP working clock of the filter is bus clock. Window_sample signal is the sample input and is not the working clock of the filter.

BR, Petr