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HOW TO DESIGN VERY LOW FREQUENCY (0.05HZ) USING PSOC 5LP | Cypress Semiconductor

HOW TO DESIGN VERY LOW FREQUENCY (0.05HZ) USING PSOC 5LP

Summary: 11 Replies, Latest post by odissey1 on 27 Aug 2016 10:20 PM PDT
Verified Answers: 2
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user_259690047's picture
User
40 posts

Hi all, i tried for design very low frequency like 0.05hz. But if i entered the value into filter configuration box, it displaying red sign. can any one tell me how to design filtering very low frequency. 

dvorakvik's picture
User
110 posts

Hi Sheik, 

use DDS with external TXCO for accuracy. Search this forum for DDS, DDS dual phase, DDS24 etc. keyword

Viktor

user_259690047's picture
User
40 posts

Thank you bro... can you please upload the documents for it. 

user_259690047's picture
User
40 posts

Yes i got the notes. i have to check............

user_342122993's picture
User
675 posts

Sheik,
The frequency of 0.05 Hz is outside of the (official) working range of the filter component. It has been designed for audio frequency range. The limitations are 24-bit internal arithmetic and amount of samples in memory (~100).

But since your frequency is very low, you can average/smooth data using CPU. If your sampling rate is high (>1-5 kHz), then pre-filter data using Filter component with cut-off frequency approx. 100 Hz, and decimate data. Now you have only about 100 samples per second, which you can easily smooth with CPU (you have to write some code for that, the simplest one is being exponential moving average filter).

user_259690047's picture
User
40 posts

Great work you have done odissey1. I watched your YouTube video. 

user_342122993's picture
User
675 posts

Sheik, what is the source of the data? Do you have any project to show?

user_259690047's picture
User
40 posts

Thank you.......... Odissey1   I am going to filter the ECG signal noise. So my source of the project is ecg signal. I don't have any idea about to design low frequency filter (0.05Hz)in PSoC 5lp. can you please give me some reference for it.

user_342122993's picture
User
675 posts

ECG signal is rather fast! The whole period is about 1 sec. To have e.g. 50 points per scan, you need 50 Hz bandwidth.

The issue with ECG is usually AC line noise (50/60 Hz). For that you need a notch filter.

user_259690047's picture
User
40 posts

If you have any example code for notch filter, could you please share that for my reference. 

user_259690047's picture
User
40 posts

Hi, i have constructed ECG signal acquisition circuit by using discrete component. Now i am going to design the same in PSoC 5lp. so i have to design the same high and low pass filter value. I dont know how to design this using filter component of  PSoC and  i am not interested to design filter with using opamp component of PSoC and external discrete component. My another debut is PSoC ADC can convert this very low frequency of  the signal or not.

 

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