I realised when I looked back at this that the codes for the components (R1, R2 etc) on the BOM and schematic did not match the stripboard layout. I have corrected them now. Following the advice of @K.ostas and @analogoutput I have also increased the resistors on the clock input and output to 10K. I’ve tested that modification and it works.
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I built the Prioritron 3 designed by @Micraster and gave it a front panel that allows me to mount it in my eurorack.
To get rid of the DC offset of the PWM based DA conversion circuit I added an 22uF capacitor to the output.
I glued a 3D-printed raster to the neopixel matrix to compartmentalise the leds so that they will not bleed any light and glued a piece of the diffuser sheet taken from a broken LCD-tv cut to size on top of that, thus resulting in a nice evenly lit display. The picture does not do it justice (the camera is too sensitive and thus maxes out).
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Hi, I’m trying to look for some advice on the MFOS 2 pole, 12db State Variable Filter with VC resonance. I works like a charm but my resonance knob isn’t fully closing which means that when this knob is fully CCW, there is still a small spike of the resonance visible on my oscilloscope. Which resistors do I need to change to get zero resonance? thanks in advance for your help. I will post the correct schematic later today.
I wanted to add the possibility of a hardware reset so that I can start the Prioritron 3 (described by @Micraster in a known state. So I looked at the pins used and found that I could use pin D4 and the PCINT mechanism for this.
For this to work I added this library to my platformio.ini (VSC project) file
neu-rah/PCINT r-site.net@^4.0.8
And these few lines to the original code:
// define a pin for the external reset signal
#define RESET_PIN 4 // D4 = PCINT20
// include the library header file
#include <pcint.h>
// Define a software interrupt service routine.
// This will reset the sequencers to their 1st step
// and initiate the 1st step.
void reset_interrupt_service_routine(void) {
step = startStep;
noteDelay.start(tempo);
if (drumBool) {
playDrums();
} else {
playNote();
}
pulseCheck = 1;
digitalWrite(CLOCK_OUT, HIGH);
timeSinceLastClock = millis();
}
Near the end of the setup()-function these 2 lines need to be added:
pinMode(RESET_PIN, INPUT);
PCattachInterrupt<RESET_PIN>(reset_interrupt_service_routine, RISING);
The original code almost completely uses the available storage on the nano, so adding this code and the library made it an even more tight fit. At a rising signal on D4 the device will now reset either its note sequencer or drum sequencer and initiate the 1st step.
As the Prioritron does not have a spare input jack, I connected D4 via a resistor to pin 8 and 16 of a 16-pin flatcable connector (the 2nd resistor is a pull down resistor). In my rack I’ve designated pin 8 and 16 to be used as a ‘bus’ for a general purpose reset signal (see Reset-O-Matic), so this works nicely for me.
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