Introducing DSPi | A powerful, user friendly and open source DSP for less than a cup of coffee

[beaker152]

apologies if this has been covered, but i have a couple of noob questions for which i haven't recognized definitive answers...

the wiring diagram below is what i found on github for the toslink output (output, right?), but i have seen other content in this thread where the toslink is connected to the 3.3V power supply and a capacitor and/or resistor is included as well as a text description indicating that a capacitor/resistor is needed when it's connected to a 5V supply

is there a diagram for the "best practice" way to connect the toslink output?
how about toslink and spdif inputs?

@Weeb Labs
@Kingsnake

 

[markz]

apologies if this has been covered, but i have a couple of noob questions for which i haven't recognized definitive answers...

the wiring diagram below is what i found on github for the toslink output (output, right?), but i have seen other content in this thread where the toslink is connected to the 3.3V power supply and a capacitor and/or resistor is included as well as a text description indicating that a capacitor/resistor is needed when it's connected to a 5V supply

View attachment 539424

is there a diagram for the "best practice" way to connect the toslink output?
how about toslink and spdif inputs?

@Weeb Labs
@Kingsnake

From what I've seen the Toshiba TX179 is rated at 5VDC though the supply tolerance is 0-7V but it may not work at 3.3V. The DLT1111A (a competitor) is rated at 3.3V and 5V. Both specify a 0.1uF cap between power and ground close to the unit.

https://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/TOTX179.pdf

https://aitendo3.sakura.ne.jp/aitendo_data/product_img/parts/SPDIF/DLT1111.pdf

Note the Pico is 3.3V so prefer to run the optical at 3.3V.

 

[ernperkins]

A quick question on the DSPi I2S formats. In Troy’s wiring diagram (LINK) the PCM1808 ADC is configured for I2S format (i.e. left justified, but delayed one BCLK). Is this the only DSPi I2S format or can the DSPi be configured for other I2S formats (e.g. left or right justified).

 

[Weeb Labs]

A quick question on the DSPi I2S formats. In Troy’s wiring diagram (LINK) the PCM1808 ADC is configured for I2S format (i.e. left justified, but delayed one BCLK). Is this the only DSPi I2S format or can the DSPi be configured for other I2S formats (e.g. left or right justified).

Strictly speaking, left and right justified are different standards and aren't really I2S at all despite being electrically compatible. DSPi only supports I2S at the moment but will likely support left and right justified at some point in the future.

apologies if this has been covered, but i have a couple of noob questions for which i haven't recognized definitive answers...

the wiring diagram below is what i found on github for the toslink output (output, right?), but i have seen other content in this thread where the toslink is connected to the 3.3V power supply and a capacitor and/or resistor is included as well as a text description indicating that a capacitor/resistor is needed when it's connected to a 5V supply

View attachment 539424

is there a diagram for the "best practice" way to connect the toslink output?
how about toslink and spdif inputs?

@Weeb Labs
@Kingsnake

As Markz mentioned, this really depends upon your chosen TX module. Different parts will support different VCC ranges but shouldn't require a resistor (can help with overshoot). The capacitor is for decoupling and not strictly necessary but recommended.

 

[somebodyelse]

is there a diagram for the "best practice" way to connect the toslink output?

The details will depend on the model of toslink transmitter you're using, so check the datasheet. A lot (most) need or at least suggest a capacitor between power and ground close to the transmitter - some datasheets even specify how close as well as the capacitor size. A few also want one between signal and ground (though I could be mixing this up with receivers?). The important part is getting one that'll work with 3.3V signal. The ones I remember want 3.3V power when using 3.3V signal, but there might be some that work with 3.3V signal and 5V power - again check the datasheet.

 

[beaker152]

have any SINAD metrics been gathered for DSPi?

 

[Salt]

have any SINAD metrics been gathered for DSPi?

Send it to Amir []

 

[Honken]

have any SINAD metrics been gathered for DSPi?

To measure what? A digital signal? It will better than you have any need for it to be.

DSPi is cool as all hell, kudos to @Weeb Labs.

 

[Weeb Labs]

have any SINAD metrics been gathered for DSPi?

It has been measured at 144dB for digital in/out.

 

[beaker152]

To measure what? A digital signal? It will better than you have any need for it to be.

DSPi is cool as all hell, kudos to @Weeb Labs.

absolutely cool as hell--i think it's awesome! just like measured data!

 

[BossBunos]

Measuring would be nice once someone has developed a board that can host the dspi with a couple of pcm dac's, pcm ADC and toslink in/out. Basically the basis for an active system

 

[john61ct]

One where the required host SBC is not already more DSP capable. That's my dilemma so far, I guess because I'm an embedded / SBC noob, no DIYer just want a finished product, case and all

 

[NotInYourHead]

Measuring would be nice once someone has developed a board that can host the dspi with a couple of pcm dac's, pcm ADC and toslink in/out. Basically the basis for an active system

I think @Weeb Labs is working on that exactly that, so we'll have to wait and see.

 

[Wesseling Audio Lab]

DSPi is with XO panel is awesome. Many thanks!

User specific mother board would be nice. Hmm, wonder how quickly I can learn KiCad

 

[Weeb Labs]

absolutely cool as hell--i think it's awesome! just like measured data!

Here is a digital in->out measurement.

 

[beaker152]

Here is a digital in->out measurement.

View attachment 540008

we data!

 

[DatSpeakerTho]

Measuring would be nice once someone has developed a board that can host the dspi with a couple of pcm dac's, pcm ADC and toslink in/out. Basically the basis for an active system

I havent built mine yet because the second I wire it all up, someone will finish their pcb with everything already on it

 

[beaker152]

i received my toslink TX, loaded the firmware, used the console on windows to define a set of filters from REW, used dspictl on my linux box to make some adjustments, re-measured the response with REW and was delighted that it (as was said in the very first post of this thread) “just worked”!

fabulous project!

 

[BossBunos]

I havent built mine yet because the second I wire it all up, someone will finish their pcb with everything already on it

Unfortunately I'm not an electrical engineer. Really hoping someone will design a board that can be used for active speakers. A board that can host 4x pcm dac and some inputs like toslink and ADC. Would be nice as a group buy.

 

[Sonic-Wall]

When can we expect the MacOS version?