PurePath Mono Mux question

Bruce12833

Prodigy 80 points

I am having some trouble using the Mono Mux component. PurePath publishes the I2C Interface

as Page 44, register 8. When I look at the generated driver I see it is using a 24 bit number to select

the input ( address 10 holds the selection). The Mux. Help says that this interface is a 32 bit number,

possibly shifted 1bit, it is a little unclear. What I am seeing is that I can set the input at compile time

through PurePath Studio. And I can also set the input at run time using a 24 bit number. But about 10ms

after the DSP init. I lose access to the mux. I am thinking that I am not writing the wrong value because

the mux help says that "MuxSelect values outside the indicated range will result in a data ouput of zero".

And what I see is multiple selections working until 10 ms after the PPS driver gets loaded with the last

selection not changing. Any help would be appreciated.

Thanks

over 16 years ago

0 J- over 16 years ago

TI__Mastermind 46195 points

Bruce,

See image below. You can always use the memory tool to verify the data that should be written to the coefficient memory.

Regards,

J-

0 kaeroul over 10 years ago in reply to J-

Intellectual 370 points

Hello, J Arbona and all...

why am I not permitted to look at the picture?

I want to control mono mux using an Arduino SPI control.

I did use below pseudo code but failed:

void loop(){

controlmux(0x00,0x30,0x2C,0x00000001);

}//end loop

void controlmux(byte PageSelectionRegister,byte I2CRegister,byte I2CPage,unsigned long muxcoeff){
digitalWrite(SS, LOW);
SPI.transfer(PageSelectionRegister<<1);
SPI.transfer(I2CPage);
digitalWrite(SS, HIGH);

digitalWrite(SS, LOW);
SPI.transfer(I2CRegister << 1);
SPI.transfer(muxcoeff>>24);
SPI.transfer(muxcoeff>>16);
SPI.transfer(muxcoeff>>8);
SPI.transfer(muxcoeff&0xff);
digitalWrite(SS, HIGH); // disable Slave Select
}

please help me?

Thanks and Best Regards,
kal

0 J- over 10 years ago in reply to kaeroul

TI__Mastermind 46195 points

Hi Kal,

The device coefficients are 24-bit. The register space is 32-bit, in which the coefficients are left aligned. You can fix your code two ways:

1. Only send first 3 leftmost bytes of the 32-bit muxcoeff.

SPI.transfer(I2CRegister << 1);
SPI.transfer((muxcoeff>>16)&0xFF);
SPI.transfer((muxcoeff>>8)&0xFF);
SPI.transfer(muxcoeff&0xFF);
SPI.transfer(0x00);

2. Shift muxcoeff to the left:

muxcoeff = muxcoeff << 8;

Regards,

J-

0x5468616E6B7321

0 kaeroul over 10 years ago in reply to J-

Intellectual 370 points

Hi J Arbona, Thanks for the reply.

The result was a great success!

what I did as per pseudo code below with my own SPI write library ,

byte data1[] = {0x00,0x00,0x01};
byte data2[] = {0x00,0x00,0x02};

void loop(){
delay(2000);
dsp.SPIwrite(0x00,0x2C); //select page
dsp.SPIwriteCoeff(0x30,data1,3); //write data of mux selection to register.
dsp.SPIwrite(0x01,0x05);//switch buffers

delay(2000);
dsp.SPIwrite(0x00,0x2C); //select page
dsp.SPIwriteCoeff(0x30,data2,3); //write data of mux selection to register.
dsp.SPIwrite(0x01,0x05);//switch buffers

}

/********************library*************************/
void Dsp::SPIwrite(byte first,byte second){
digitalWrite(SS, LOW);
SPI.transfer(first<<1);
SPI.transfer(second);
digitalWrite(SS, HIGH);
}

void Dsp::SPIwriteCoeff(byte Register,byte* data,byte length){
digitalWrite(SS, LOW);
SPI.transfer(Register<<1);
for(byte c = 0; c < length; c++){
SPI.transfer(data[c]);
}
digitalWrite(SS, HIGH);
}
/********************library*************************/

simplify algo:

1. select page.

2. write data of mux selection to register.

3. switch buffer.

4. repeat 1.

Hope it helps others too.

Thanks again J,

Best regards,
kal

0 J- over 10 years ago in reply to kaeroul

TI__Mastermind 46195 points

kal,

Thanks for following up!

Regards,

J-

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PurePath Mono Mux question