Category: Electronics

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LtSpice Potentiometer Model

It takes about 20 seconds to put a potentiometer model in LtSpice. I have no idea why it wasn’t included. Regardless….

— Download the “Pot” folder at https://github.com/brandondrury/LTspice-Libraries

— Find your C:\Users\YOUR_USERNAME\Documents\LTspiceXVII\lib\ folder
— Place pot.asy in your “sym” folder. C:\Users\YOUR_USERNAME\Documents\LTspiceXVII\lib\sym\
— Place pot.sub in your “sub” folder. C:\Users\YOUR_USERNAME\Documents\LTspiceXVII\lib\ sub\
— Click the text tool. Select “SPICE Directive” and paste in .include pot.sub.
— Restart LTspice
— Creat a new schematic. Press F2. You should see “Pot”.

The wiper is on a 0-1 scale. 1 = 100%. 0.5 = 50%.
There is a glitch that occurs if a resistor is 0 ohms in LtSpice. So, this pot actually is limited from 0.001 – 0.999 so don’t freak out if your values are off by 0.1% on extreme settings.

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MIDI Test Code on Arduino and STM32 Blue Pill

This code turns the onboard PC13 LED of the STM32 Blue Pill on when a MIDI NoteOn message is received and turns the LED off when a MIDI Noteoff message is received. It’s my preferred way to confirm that a MIDI circuit is working. It relies on the Arduino MIDI Library.

#include <MIDI.h>

#define LED PC13 // LED pin on Arduino Uno

MIDI_CREATE_DEFAULT_INSTANCE();

void doSomeStuffWithNoteOn(byte channel, byte pitch, byte velocity);
void NoteOff(byte channel, byte note, byte velocity);

void setup()
{
  pinMode(LED, OUTPUT);
  MIDI.begin();
  MIDI.setHandleNoteOn(doSomeStuffWithNoteOn);
  MIDI.setHandleNoteOff(NoteOff);
}

void loop()
{

  MIDI.read();
}

void doSomeStuffWithNoteOn(byte channel, byte pitch, byte velocity)
{
  // note on code goes here
  digitalWrite(PC13, LOW);
}

void NoteOff(byte channel, byte note, byte velocity)
{
  // note off code goes here
  digitalWrite(PC13, HIGH);
}
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Heating Bed and Nozzle Simultaneously On CR-10 In Cura

On my CR-10, the nozzle heats up and then the bed heats up. This seems like a waste of time particularly in that I need to make sure the first layer of the print goes down correctly. After that, I don’t care. This sequentially heating dramatically increases my time investment in a print.

Warning: I’ve heard that the stock CR-10 power supply is trash and can’t handle this. I’ve been doing it for about a year (hundreds of prints) with no issue. Use at your own risk.

In Cura, go to Settings > Printer > Manage Printer > Machine Settings > Printer

———START G-CODE

M140 S{material_bed_temperature} ; start preheating the bed WITHOUT wait to what is set in Cura

M104 S{material_print_temperature} T0 ; start preheating hotend WITHOUT wait to what is set in Cura

M190 S{material_bed_temperature} ; start heating the bed to what is set in Cura and WAIT

M109 S{material_print_temperature} T0 ; start heating hotend to what is set in Cura and WAIT

M201 X500.00 Y500.00 Z100.00 E5000.00 ;Setup machine max acceleration

M203 X500.00 Y500.00 Z10.00 E50.00 ;Setup machine max feedrate

M204 P500.00 R1000.00 T500.00 ;Setup Print/Retract/Travel acceleration

M205 X8.00 Y8.00 Z0.40 E5.00 ;Setup Jerk

M220 S100 ;Reset Feedrate

M221 S100 ;Reset Flowrate

G28 ;Home

G92 E0 ;Reset Extruder

M92 E98 ; Brando configured extruder e-steps

G1 Z2.0 F3000 ;Move Z Axis up

G1 X10.1 Y20 Z0.28 F5000.0 ;Move to start position

G1 X10.1 Y200.0 Z0.28 F1500.0 E15 ;Draw the first line

G1 X10.4 Y200.0 Z0.28 F5000.0 ;Move to side a little

G1 X10.4 Y20 Z0.28 F1500.0 E30 ;Draw the second line

G92 E0 ;Reset Extruder

G1 Z2.0 F3000 ;Move Z Axis up

——— END G-CODE ————————–

G91 ;Relative positionning

G1 E-2 F2700 ;Retract a bit

G1 E-2 Z0.2 F2400 ;Retract and raise Z

G1 X5 Y5 F3000 ;Wipe out

G1 Z10 ;Raise Z more

G90 ;Absolute positionning

G1 X0 Y{machine_depth} ;Present print

M106 S0 ;Turn-off fan

M104 S0 ;Turn-off hotend

M140 S0 ;Turn-off bed

M84 X Y E ;Disable all steppers but Z