Re: DSP cheap for qrp

Joshua Blanton


I looked up the specs on the Teensy audio board, and I don't see any reason that it couldn't be wired to an STM32 (it's just an I2S codec; only marginally different than using separate ADC and DAC boards) - but it does somewhat defeat the low-cost goal (as the audio board is 3x the price of the core processor board!).  It has the huge advantage of being of known quality, though, as it's been used in several SDR projects at this point.

There are pre-assembled modules for DACs and ADCs that are available from the usual China resellers; I found a PCM1808 board (a 24bit/96kHz ADC) reasonably available, and also a PCM5102A board (up to 32bit/384kHz!) that is available.  I have direct experience with the PCM180x family of ADCs, but know nothing about the PCM510x family.


The JackAl looks like a really interesting project.  The Teensy in general looks interesting, as it can leverage the Arduino ecosystem.  I've never really delved into the Arduino realm, as it never made sense professionally - but I have family and friends who use it often, along with everyone here and in many radio projects.

Happy New Year, everyone!
Josh, KB8NYP

On Tue, Jan 1, 2019 at 10:41 AM Jack Purdum via Groups.Io <> wrote:
JackAl is using the Teensy 3.6 and has the speed (180MHz) and memory resources (1Mb flash, 256K SRAM) for us to do very good DSP using their audio board. Paul has written a very useful FFT library for it, too. The bad news is that the Teensy 3.6 and audio board together cost $44. On the plus side, it works very well with the Arduino IDE.

Jack, W8TEE

On Tuesday, January 1, 2019, 4:06:12 AM EST, giuseppe callipo <ik8yfw@...> wrote:

Thanks Josh and Happy new year. 
The first project was that based on f103, It was like a challenge to make e cheapest dsp ever, if you follow the link GitHub of the 103 you will found the schematic jpg.
Forse the Stm32f4 instead, i will consider also a discovery series st board but It Is more expensive and the ADC on boarboard can work only at audio frequencies. I make this project as starting point, for example increasing the sample frequency you can transform It from audio DSP to if-dsp and out inside other code to handle modulation like the ArmRadio project that you found with a simple search. Of course of the finalmente use Is as audio DSP the best solution Is using a discovery board or ADC DAC card interfaced by i2c, the code change only the ADC DAC setup. In the next days i Hope to add some info about the schematic, but are only wire cinnections and a small module to get signal in out the Stm32.
There are some experiences with the convolution filtering that need to do but Need a lot of study about It 

Have a nice day, if you can some tests send me info about It.
Best 73 and Happy new year. Ik8yfw

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