cancel
Showing results for 
Search instead for 
Did you mean: 

PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

 Hi all

   

Please help me how to use 2x analog filter component - visible only in advanced analog view mode. This is secret analog component ?

   

Very thanks any info Kamil

0 Likes
30 Replies
Anonymous
Not applicable

There are two LPF Blocks available in PSoC 3/5. Each LPF can be tuned by changing the values of Resistor (R) and Capacitor (C). The Resistor value can be selected as 208K ohms or 1.04 M ohms. The Capacitor value can be selected as 5pF or 10pF. Hence four cut-off frequencies are supported by the LPF, that is, 15KHz, 30KHz, 76KHz and 153KHz.

   

 

   

Refer to the figure below which shows the Routing of the analog LPF.

   

 

   

 

   

   

 

   

 

   

The inputs are selectable in a 2:1 mux for each LPF. On the left side, the LPF inputs are AMUXBUSL and AGL0. On the right side, the inputs are AMUXBUSR and AGR0. The outputs are connected through switches to abusL0 and abusR0, respectively.

0 Likes
Anonymous
Not applicable

Hi JLS1,

   

 

   

Please refer to the Technical reference Manual (TRM) for more details on this block. The TRM can be found at http://www.cypress.com/?id=2232&rtID=117.

   

 

   

The LPF control registers are LPF0_CR0 and LPF1_CR0. The Control register is as shown below:

   

 

   

   

 

   

When csel = 0, C is 5pF

   

            csel = 1, C is 10pF.

   

 

   

When rsel = 0, R is 208k ohm

   

           rsel = 1, R is 1.04M ohm

   

 

   

When swout = 0, LPF output is not connected

   

            swout = 1, LPF output is connected to Analog local bus 0.

   

 

   

When swin = 00, inputs are not connected.

   

            swin = 01, Analog Global 0 is connected (AGL0 o/ AGR0)

   

            swin = 10, Analog Muxbus is connected (AMUXBUSL / AMUXBUSR)

   

            swin = 11, Both Analog Global and Analog Mux are connected.

0 Likes
Anonymous
Not applicable

These filters have only 4 cut-off frequencies. Since it acts as a simple R-C Low pass filter, the impedance matching has to be taken care of.

   

If you are intending to use this filter, then you'll have to buffer its input / output via an opamp or PGA in voltage follower mode. Else the signal will be attenuated.

0 Likes
Anonymous
Not applicable

 Hi dasg

   

Very thanks info about LP filter.

   

Please is possible make simple working module ? This is very hard for me im dont understand how to use registers.

   

 

   

Many many thanks 

   

Kamil

0 Likes
Anonymous
Not applicable

Hi JLS1,

   

 

   

As you are not comfortable using registers, it will be easier to use the component to configure and use the LPF.

   

The schematic will look as shown below:

   

 

   

   

 

   

The LPF's output is buffered via opamp and put out on an analog pin.

   

Please be aware that this LPF component is just a trial component and is not fully tested. You have choice of four frequencies - 15kHz, 30kHz, 76kHz and 153kHz.

   

The output impedance of the LPF is high, hence the output should be buffered before bringing it out on a pin.

0 Likes
Anonymous
Not applicable

A simple project is attached in which the LPF output is brought out to a pin via an opamp operating as voltage follower. The LPF component is also included in it.

   

 

   

Thanks,

   

dasg

0 Likes
Anonymous
Not applicable

 Hi dasg

   

Many thanks this is very usefull module for me.

   

Kamil

0 Likes
Anonymous
Not applicable

You're welcome Kamil.
 

   

All the Best!
 

0 Likes
Anonymous
Not applicable

 Hola.

Estoy haciendo un filtro pasabandas de 4 orden con un Psoc de la familia 1.

No entiendo bien los parámetros de frecuencia central y ancho de banda, tenía mis parámetros de la siguiente manera:

La señal que quiero filtrar está entre 20 Hz y 500 Hz; si sigo la lógica de filtros la frecuencia central está dada por la raíz del producto de éstas dos frecuencias, es decir FC = SQRT(500*200) = 100 Hz; ahora bien, el ancho de banda es la diferencia de las dos frecuencias, es decir BW = 500 - 20 = 480 Hz

Con esta lógica no funciona mi filtro.

Agradecería que me pudieran aclarar o dar un tutorial de cómo calcular bien el ancho de banda y la frecuencia central para ese pasabandas.

Gracias

0 Likes
JoMe_264151
Expert II
        Can someone translate this manually, so that no Information gets lost? Bob (small window)   
0 Likes
crcac_264396
New Contributor II
        Translated: Hi, I am doing a 4th-order, band pass filter with a PSOC1. I don’t understand well the parameters for the center frequency and bandwidth. I had my parameters like this: The signal I want to filter is between 20 and 500 Hz. If I follow filter logic, the center frequency is given by the root of the product of these two frequencies, in other words FC = SQRT(500*200) = 100 Hz. Also, the bandwidth is the difference of the two frequencies, that is BW = 500 – 20 = 480 Hz. Using this logic my filter does not work. I would appreciate if someone could clear this up for me, or show me a tutorial of how to correctly calculate the bandwith and frequency centerpoint (center frequency) for this band pass filter. Thanks,   
0 Likes
JoMe_264151
Expert II
        What exacly does not work as you expect? Do you have a scope picture? Can you post the complete project here so that we all can have a look at? (Use the Archive function of Designer) Bob (small window)   
0 Likes
JoMe_264151
Expert II
        Will this be alright for you? Bob   
0 Likes
Anonymous
Not applicable

 Would this moved back to PSoC1sub forum?

0 Likes
Anonymous
Not applicable

 Sorry, I mean the new one, not the original one. 

0 Likes
ETRO_SSN583
Esteemed Contributor

You want to use geometric mean or arithmetic mean ? 100 Hz vs 260 Hz ?

   

 

   

www.sengpielaudio.com/calculator-geommean.htm

   

 

   

Equiripple, linear phase, maximally flat.....?

   

Out of band rejection ?

   

2'ond order, 4'th order ?  (Above will tell us this)

   

 

   

 

   

Regards, Dana.

0 Likes
JoMe_264151
Expert II
        It was Jataalfer's very first post, wrong language, wrong forum, hijacked thread... I did the same when I started things like that. Bob (Still getting only that &/$§&# small window!!!)   
0 Likes
ETRO_SSN583
Esteemed Contributor

An excellent tool where you can establish filter order needed to implement

   

a set of design goals and evaluate filter -

   

 

   

www.ti.com/tool/filterpro

   

 

   

Regards, Dana.

0 Likes
ETRO_SSN583
Esteemed Contributor

Bob, using Firefox, I clear all history, and after 1 or 2 trys the large window is restored.

   

Restart browser after each attempt.

   

 

   

Regards, Dana.

0 Likes
Anonymous
Not applicable

The LPF component is not available in PSoC Creator 3.0. I can open the sample project above and it updates the components OK, but I can't copy/paste it to a current project. Am I missing something? I see the grayed-out blocks in the Analog section of .cydwr but I have no way to use them.

0 Likes
ETRO_SSN583
Esteemed Contributor

Does not appear to be part of the standard library, did you import

   

the component from the project in this thread ? Don't forget to update

   

the dependencies setting for this project.

   

 

   

video.cypress.com/video-library/video/Corporate/PSoC-Creator-Tutorial-Importing-Components/206746881...

   

 

   

Note the accuracy/tolerance of the cutoff freq for this componet very poor. The absolute R tolerance

   

is poor so you will get a big variation. You can get an idea of the tolerance by looking at the TIA feedback

   

R tolerance in datasheet. 60%

   

 

   

Regards, Dana.

0 Likes
JoMe_264151
Expert II

Archive of LPF component attached. Import into your project then there will be a new tab in the Component Catalog named "CyAppsLib" There You'll find the component now.

   

 

   

Bob

0 Likes
Anonymous
Not applicable

Hi Gautam Das,

   

Can you tell me how you created this Component (Low Pass Filter - LPF) ? I have some problems with creating new components 😞

   

Thanks.

0 Likes
ETRO_SSN583
Esteemed Contributor

You are aware PSOC 3 /  5LP has a digital filter in it ?

   

 

   

Also you can use an OpAmp as a LPF by running at at low power thereby

   

reducing its GBW, or use it in a general Salllen-Key configuration.

   

 

   

Maybe describe what you are filtering and what performance you want out

   

of the filter would help with recomendations.

   

 

   

Regards, Dana.

0 Likes
Anonymous
Not applicable

Hi danaaknight, thanks for answer.

   

I am trying to make a low pass filter with cut frequency at 212Hz. I used an circuit that works with this frequency but it has external components and i need a circuit without external components.

   

I am sending attachment with image of my circuit.

0 Likes
ETRO_SSN583
Esteemed Contributor

The LPF component has fixed cutoffs, none of which come close

   

to the 212 Hz you need. Thats because of the available onchip Rs and

   

Cs available.

   

 

   

If you are using PSOC 3 or 5LP then use the DFB, otherwise you will have

   

to use external components. Or use code + A/D to do your own filter algorithim

   

if using PSOC 4. Note PSOC 4 has a single cycle digital 32 bit multiplier in

   

it that facilitates digital filtering.

   

 

   

There is this approach, but if using PSOC 4 would have to be 4M family.

   

 

   

    

   

          http://www.cypress.com/?app=forum&id=2492&rID=76870

   

 

   

And this -

   

 

   

    

   

          

   

http://www.cypress.com/?rID=2813     AN2099

   

 

   

 

   

Regards, Dana.

0 Likes
Anonymous
Not applicable

Thank you Dana for helping me. I will study more about this components that you sent to me now.

   

 

   

Regards, Miguel.

0 Likes
ETRO_SSN583
Esteemed Contributor

For PSOC 4 use the MULS instruction, inline ASM, to perform the

   

single cycle multiply -

   

 

   

    

   

          http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCcQFjAB&url=http%3A%2F%2Finfoce...

   

 

   

Regards, Dana.

0 Likes
AnEy_1336741
New Contributor II

Hello Everybody!

   

Seems as Cypress has taken the analog LPF from the available components. Even the import doesn't work anymore. What happened?

   

Thanks and bye!

   

Andreas

0 Likes
odissey1
Honored Contributor II
        EyA, Use filter component which is posted by Gautam Das at the beginning of the thread. It uses Cypress LPF, but it is not the same   
0 Likes