[GreenKeys] Minimal DSP TU Working!

Sat Mar 19 01:57:30 EDT 2022

Gil I am working on something non rtty  related using stm32f4.  Highly recommended.  Using azure rtos and cube.  It seems just as time consuming and complicated as it ever was to bring up a bare board - complete with tool bugs etc. 
Gerry

Sent from my iPhone

> On Mar 18, 2022, at 10:15 PM, gil baudot.net <gil at baudot.net> wrote:
> 
> 
> Hi Harold:
> 
> That dsp-tu is a great idea, and looks like a fun bit of coding.  I am currently playing with an stm32f4 part to see if I can figure out the cmsis-dsp library for some filtering and such.  I think someone said something about a rabbit hole -- it does indeed seem to consume a fair bit of time.
> 
> gil
> 
> From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net> on behalf of Harold Hallikainen via GreenKeys <greenkeys at mailman.qth.net>
> Sent: Friday, March 18, 2022 7:44 AM
> To: steve bennett <raleigh_ranger at yahoo.com>
> Cc: greenkeys at mailman.qth.net <greenkeys at mailman.qth.net>
> Subject: Re: [GreenKeys] Minimal DSP TU Working!
>  
> They did not have any DSP classes when I was in school long ago. In my
> work, I worked with DSP consultants who made the chips do what I needed. I
> then communicated with the chips over SPI for control. I am now trying to
> learn some DSP. The TU seems like a good learning experience. With the
> biquad code I found online, implementing biquad filters is pretty easy.
> The code provides an easy way to initialize the filter and then a short
> function to run on each sample. A lot of DSP stuff uses DMA ping pong
> buffers and then processes the data in batches. In my TU, I am doing
> everything on a sample by sample basis. The system uses a timer to
> generate an 80 kHz PWM output. Every 10 cycles of that timer (8 kHz), an
> ADC sample is pulled, the ADC restarted for the next sample, then the
> sample run through the DSP code. I will be adding code to set a pin high
> at the start of the DSP code and low on the way out so I can see how much
> processor time is being taken.
> 
> This project is one of many, so at times it is slow going.
> 
> Harold
> 
> 
> On Fri, March 18, 2022 6:13 am, steve bennett wrote:
> >  Harold,
> > Â  I took a DSP class in college. I wrote some code to process signals off
> > line.How do you write code that works in real time?I'm sure entire books
> > have been written on the subject so it would be hard to answerin a single
> > email.
> > -Steve
> >     On Friday, March 18, 2022, 12:30:09 AM EDT, Harold Hallikainen via
> > GreenKeys <greenkeys at mailman.qth.net> wrote:
> >
> >  I'm using Microchip MPLAB-X for a PIC32MZ microcontroller. The compiler
> > is
> > a microchip version of gcc.
> >
> > The biquad C code is attached.
> >
> > Harold
> >
> >
> > On Thu, March 17, 2022 9:01 pm, brad at bfayette.com wrote:
> >> Can you tell us what your dev environment is, and which compiler? Also,
> >> I
> >> am interested in the biquad class. Thanks!
> >>
> >> Regards,
> >> Brad Fayette
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