Search found 18 matches

by KenLaszlo
Wed Nov 29, 2017 11:49 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Well this appears to be the thing :) My approach was that the frequency was controlled by a phase accumulator variable, rather than a set frequency in which data is sent via DMA. So (in simple terms) the data send rate is set, but the amount of samples being sent changes. In fact, I have done just t...
by KenLaszlo
Wed Nov 29, 2017 11:20 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Thanks. I'm just hacking spi.h now. spi_tx_reg(_currentSetting->spi_d, data); // write the data to be transmitted into the SPI_DR register (this clears the TXE flag) I'm looking with interest at spi.dmaSend and your spi.dmaSendAsync that you developed for use with your Neopixels. Would I need any sp...
by KenLaszlo
Tue Nov 28, 2017 1:40 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Thanks, Steve. The PT8211 has a maximum rated clock frequency of 20Mhz . . .. however . . . my thinking was the same as yours ;) . I changed the clock rate division for 72 / 2 (36Mhz) and it still seems to run fine. Looks like the PT8211 (well, my chip at least) can be overclocked. Further testing t...
by KenLaszlo
Tue Nov 28, 2017 11:23 am
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Thanks, yes. I can confirm that getting the table out of flash memory does make it a fraction faster. Not dramatically so, but a definite increase. In a timed loop, the time taken reduced from 3.20 microseconds to 3.14 microseconds. I recently experimented with overclocking the chip to 128Mhz and ch...
by KenLaszlo
Mon Nov 27, 2017 10:24 am
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Hey Roger Thanks for the additions - Yes, I understand. I'm coming from an AVR background, so not fully conversant with how these new 32 bit devices run. Bizarrely, I noticed that grabbing a 16-bit sample from the wavetable in flash memory (Sine for example) was a fraction slower than doing one or t...
by KenLaszlo
Sun Nov 26, 2017 7:06 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

Thank you all for your assistance and further input. These little PT8211s are genius! I suspect his is your issue, that capacitor/resistor combination is going to act as an R/C filter, and is going to have a negative effect With input signal as below the RC will "round the edges", while the CR will ...
by KenLaszlo
Fri Nov 24, 2017 4:31 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

I managed to get ten PT8211 SMD Chips from eBay (sent from China) for 1.88 USD.
I got four SMD to DIP8 Adapter PCB Boards from a UK seller for 1.89 UKP.
Dirt cheap.

Ken
by KenLaszlo
Fri Nov 24, 2017 2:13 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

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by KenLaszlo
Fri Nov 24, 2017 2:12 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 781

Dual LFO with choice of waveforms using PT8211 and Blue Pill

Hi folks Roger encouraged me to make a post here, so here's me 'taking the plunge'. My first code-snippet / project. From reading Vasillis code example using the PT8211 (thank you!), if spurred me on to create a dual LFO. I was interested in getting two independant waveforms out of the chip with a c...
by KenLaszlo
Fri Nov 24, 2017 12:08 am
Forum: General discussion
Topic: Newbie question about 'short' and 'uint16_t' data types
Replies: 10
Views: 272

Re: Newbie question about 'short' and 'uint16_t' data types

Post the code? I might just do that . . . :)
It's pretty much optimised but it could do with expert eyes.
We'll see what this weekend brings.

Ken