FreeDSP Catamaran A/B

[CyberPit]

Hello, DIY volks,
I updated FreeDSP Catamatan A/B board and schematic design. A new feature is automatic DSP firmware reload on the transition of A/B program switching. The reset button is not required anymore!
JLPCB's PCBA information is also updated.

[FreeDSP Project Git-Hub LINK]
https://github.com/freeDSP/FreeDSP_Catamaran_AB

Designing Pleasure
CyberPit

 

[smagtech]

Hi Pit Great work . I have a question is it possible give I2s input to "free DSP board". like from raspberry pi I2s out to I2s input to "free DSP board". is it possible.

Love this project.

 

[CyberPit]

smagtech-San,
Thank you for your response.

I have a question is it possible give I2s input to "free DSP board". like from raspberry pi I2s out to I2s input to "free DSP board". is it possible.

Technically some limits exist, those belong to the I2S I/O limits, and missing the sampling rare conversion block.

• The Sampling rate should be the same as interlinking and processing DSP's fs.
• ADAU1701 doesn't have ASRC

If you play various music sources today, the sampling rate will change frequently. As a result of this, DSP processing filter coefficients should be changed on the fly or should have an external ASRC path before inputting the data into the DSP.
According to those reasons, FreeDSP Catamaran is specially focused on Analog I/O Application design as you can see.

Following few weeks, I will release the design FreeDSP OCTAVIA. It has Raspberry-Pi slot, USB, Optical/Coax S/PDIF, and analog input. 8 channels UNBAL/DIFF/BAL output feature. If you want to insert Raspberry-pi anyway, please have a look at that thread.

CyberPit

 

[smagtech]

Thank you Pit for quick answer. i will be waiting for " FreeDSP OCTAVIA ". i have a idea of controlling eeprom from Arduino so even more epprom ic. also volume control from digital potentiometer like MCP42010 Ic. with graphic display. MCP42010 has 2 10k digital potentiometer so we can control left and right volume. what do you think Pit.

 

[CyberPit]

Hi smagtech-San,
Additional CPU control enables various attractive features as you mentioned and more. The board debugging will be a little bit difficult but it is not a matter for you.
I do not recommend using MCP42010 for the Master output volume following points...

From the MCP41XXX/42XXX datasheet says

• FIGURE 2-23: 10 kΩ Wiper Resistance vs. Voltage. indicates non-linear characteristics will make distortion in the biased AC/Audio applications.
• FIGURE 2-17: Digital Feed through vs. Time indicates a big click on a changing the gain. (>100mV)
• The liner curve (called as "B" curve) is very few steps of small volume control.
• Low PSRR will be a critical power supply requirement.

According to those reasons, You'd better choose ordinary audio DCA something like MUSES72323, etc...

CyberPit

 

[smagtech]

Thank you for clarifying about using MCP42010. waiting for " FreeDSP OCTAVIA "

Thank you once agan CyberPir.