Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
ShHo_2768971
Level 1
Level 1
Welcome! First question asked First reply posted

I am planning to design Multi Channel Audio Mixer + Summing unit which will take audio tracks/signals from different sources/instruments and mix/sum/block some or all the signals to outputs with PSoC Amux (into 2 Channel mixed audio outputs)

I would appreciate if someone can share some additional electrical characteristics of Amux, what I am looking for is not available on this datasheet

https://www.cypress.com/file/127201/download

It says only this :

DC and AC Electrical Characteristics The AMux operates at all valid supply voltages.

Here are my queries -

1. How much current can Amux paths carry ?

2. Can Amux route isolated signals ? ( signal sharing no common ground with PSoC Chip, kind of like EM relay )

3. What is the trace resistance from input to output through Amux ?

4. Does Amux switching cause audio level noise ?

5. What is the Parasitic Capacitance of Amux circuits ? (to avoid unwanted RC filters)

6. Can Amux carry AC audio signal below PSoC Vss Voltage (Gnd) ?

I have been trying this with two different audio sources (laptop and phone) playing two songs

psoc aud sum.png

It somewhat worked with few issues as follows :

1. Signal bleeding/cross-talk from some of the channels

2. Signal Attenuation/Loss of gain

Otherwise, the audio mixing and blocking did worked

Analog pins are set as Strong Drive

Amux is set with Maximum Isolation

Opamp is set for High BW/Power, Medium Cap Compensation

SW is an Input switch for enabling/disabling one or all input audio lines

LED blinks to indicate input combinations

#include <project.h>

int main()

{

    AMux_Init();

    Pre_Amp_Init();

    CyDelay(200);

   

for(;;)

    {

        while(SW_Read()){LED_Write(1);}

        AMux_DisconnectAll();

        while(!SW_Read())

        {LED_Write(1); CyDelay(50);LED_Write(0);CyDelay(50);}

       

        if(SW_Read()==0)

        {

            for(int j=0;j<2;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

          AMux_Disconnect(1);AMux_Connect(0);

       

        }

        while(SW_Read()){LED_Write(1);}

       

        if(SW_Read()==0)

        {

            for(int j=0;j<4;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

          AMux_Disconnect(0);AMux_Connect(1);

        }

         while(SW_Read()){LED_Write(1);}

       

        if(SW_Read()==0)

        {

            for(int j=0;j<6;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

          AMux_Connect(0);AMux_Connect(1);

        }

         while(SW_Read()){LED_Write(1);}

       

        if(SW_Read()==0)

        {

            for(int j=0;j<10;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

          AMux_Connect(2);AMux_Disconnect(1);AMux_Disconnect(3);

        }

         while(SW_Read()){LED_Write(1);}

       

         if(SW_Read()==0)

        {

            for(int j=0;j<12;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

          AMux_Connect(3);AMux_Disconnect(0);AMux_Disconnect(2);

        }

         while(SW_Read()){LED_Write(1);}

       

        if(!SW_Read())

        {

          for(int j=0;j<8;j++)

            {

          LED_Write(1); CyDelay(200);LED_Write(0);CyDelay(200);

            }

        AMux_DisconnectAll(); 

        }

         while(SW_Read()){LED_Write(1);}

       

       

    }

}

Message was edited by: ShHo PSoC Sch added and some of the experimental finding are listed.

0 Likes
1 Solution
Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi Hossain,

1. How much current can Amux paths carry ?

     This is not characterized. Could you let us know your requirements ?

2. Can Amux route isolated signals ? ( signal sharing no common ground with PSoC Chip, kind of like EM relay )

    Amux switches will be defined with respect to PSoC VSS and VDD

3. What is the trace resistance from input to output through Amux ?

     Kindly use the ohm meter tool in PSoC Creator(CYDWR-> Anlog tab). Search in help for more details.

4. Does Amux switching cause audio level noise ?

    Amux switching is done using connecting and disconnecting

5. What is the Parasitic Capacitance of Amux circuits ? (to avoid unwanted RC filters)

         This also we might not have characterized. Are you facing any specific issues with your design ? Kindly let us know.

6. Can Amux carry AC audio signal below PSoC Vss Voltage (Gnd) ?

     This will not be possible as the device is not expected to work on this range.

Best Regards,
Vasanth R S

View solution in original post

0 Likes
2 Replies
lock attach
Attachments are accessible only for community members.
ShHo_2768971
Level 1
Level 1
Welcome! First question asked First reply posted

Here is the project (AudioMux inside zip)

0 Likes
Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi Hossain,

1. How much current can Amux paths carry ?

     This is not characterized. Could you let us know your requirements ?

2. Can Amux route isolated signals ? ( signal sharing no common ground with PSoC Chip, kind of like EM relay )

    Amux switches will be defined with respect to PSoC VSS and VDD

3. What is the trace resistance from input to output through Amux ?

     Kindly use the ohm meter tool in PSoC Creator(CYDWR-> Anlog tab). Search in help for more details.

4. Does Amux switching cause audio level noise ?

    Amux switching is done using connecting and disconnecting

5. What is the Parasitic Capacitance of Amux circuits ? (to avoid unwanted RC filters)

         This also we might not have characterized. Are you facing any specific issues with your design ? Kindly let us know.

6. Can Amux carry AC audio signal below PSoC Vss Voltage (Gnd) ?

     This will not be possible as the device is not expected to work on this range.

Best Regards,
Vasanth R S

0 Likes