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