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ESP32TimerInterrupt Simple Example

Here’s a stripped down example of Khoi Hoang’s ESP32TimerInterrupt library. The library claims to run up to 16 compares (or alarms) on one, single timer. It seems to work well although I’ve only tested 3 timers thus far. I plan to use it on my Idiot Christmas Light Controller controlling triacs.

include <Arduino.h>
   For ESP32 boards
   Written by Khoi Hoang
 Built by Khoi Hoang
   Licensed under MIT license
 This is the most basic example using Khoi Hoang's ESP32TimerInterrupt library.  
   The library works well, but I found myself wanting an ultra basic version to understand the functionality
 include "ESP32TimerInterrupt.h"
 // Change these to whatever GPIO you'd like to toggle
 define LED0 25 // GPIO 25
 define LED1 27 // GPIO 27
 define LED2 33 // GPIO 33
 // The lenght of each timer in milliseconds
 define TIMER0_INTERVAL_MS 100
 define TIMER1_INTERVAL_MS 3000
 define TIMER2_INTERVAL_MS 400
 void IRAM_ATTR TimerHandler0(void)
   static bool toggle0 = false;
 //timer interrupt toggles pin LED0
   digitalWrite(LED0, toggle0);
   toggle0 = !toggle0;
 void IRAM_ATTR TimerHandler1(void)
   static bool toggle1 = false;
 //timer interrupt toggles LED1
   digitalWrite(LED1, toggle1);
   toggle1 = !toggle1;
 void IRAM_ATTR TimerHandler2(void)
   static bool toggle2 = false;
 //timer interrupt toggles LED2
   digitalWrite(LED2, toggle2);
   toggle2 = !toggle2;
 // Init ESP32 timer 0,1, and 2
 ESP32Timer ITimer0(0);
 ESP32Timer ITimer1(1);
 ESP32Timer ITimer2(2);
 void setup()
 pinMode(LED0, OUTPUT);
   pinMode(LED1, OUTPUT);
   pinMode(LED2, OUTPUT);
   while (!Serial)
 Serial.print(F("\nStarting TimerInterruptTest on "));
 Serial.print(F("CPU Frequency = "));
   Serial.print(F_CPU / 1000000);
   Serial.println(F(" MHz"));
 // Using ESP32  => 80 / 160 / 240MHz CPU clock ,
   // For 64-bit timer counter
   // For 16-bit timer prescaler up to 1024
 // Setup Timer0
   // Interval in microsecs
   if (ITimer0.attachInterruptInterval(TIMER0_INTERVAL_MS * 1000, TimerHandler0))
     Serial.print(F("Starting  ITimer0 OK, millis() = "));
     Serial.println(F("Can't set ITimer0. Select another freq. or timer"));
 // Setup Timer1
   // Interval in microsecs
   if (ITimer1.attachInterruptInterval(TIMER1_INTERVAL_MS * 1000, TimerHandler1))
     Serial.print(F("Starting  ITimer1 OK, millis() = "));
     Serial.println(F("Can't set ITimer1. Select another freq. or timer"));
 // Setup Timer2
   // Interval in microsecs
   if (ITimer2.attachInterruptInterval(TIMER2_INTERVAL_MS * 1000, TimerHandler2))
     Serial.print(F("Starting  ITimer2 OK, millis() = "));
     Serial.println(F("Can't set ITimer1. Select another freq. or timer"));
 void loop()
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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

— 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


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

void setup()
  pinMode(LED, OUTPUT);

void loop()

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


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