Teensy 4.1 and ShiftPWM library

[cfredisded]

Does shiftPWM work with the teensy 4.1?

I found this thread but I'm not sure if its indicating that it works or not.

Also will it work with a 3mm 'common anode' RGB led like this schematic?
I'm using 6 74hc595BQ

Here's the code I'm trying...

// You can choose the latch pin yourself.
const int ShiftPWM_latchPin=9;

#define SHIFTPWM_NOSPI // ** uncomment this part to NOT use the SPI port and change the pin numbers. This is 2.5x slower **
const int ShiftPWM_dataPin = 25;
const int ShiftPWM_clockPin = 10;

// If your LED's turn on if the pin is low, set this to true, otherwise set it to false.
const bool ShiftPWM_invertOutputs = true;

// You can enable the option below to shift the PWM phase of each shift register by 8 compared to the previous.
// This will slightly increase the interrupt load, but will prevent all PWM signals from becoming high at the same time.
// This will be a bit easier on your power supply, because the current peaks are distributed.
const bool ShiftPWM_balanceLoad = true;

#include <ShiftPWM.h>   // include ShiftPWM.h after setting the pins!

// Here you set the number of brightness levels, the update frequency and the number of shift registers.
// These values affect the load of ShiftPWM.
// Choose them wisely and use the PrintInterruptLoad() function to verify your load.
unsigned char maxBrightness = 100;
unsigned char pwmFrequency = 75;
unsigned int numRegisters = 6;

elapsedMillis randomTimer;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  // Sets the number of 8-bit registers that are used.
  ShiftPWM.SetAmountOfRegisters(numRegisters);
  // SetPinGrouping allows flexibility in LED setup. 
  // If your LED's are connected like this: RRRRGGGGBBBBRRRRGGGGBBBB, use SetPinGrouping(4).
  ShiftPWM.SetPinGrouping(1); //This is the default, but I added here to demonstrate how to use the funtion  
  ShiftPWM.Start(pwmFrequency,maxBrightness);

}

void loop() {
  // put your main code here, to run repeatedly:
  if (randomTimer >= 500){
    Serial.println("testTimer");
    int randomLed = random(0, 14);
    int randomR = random(0, 254);
    int randomG = random(0, 254);
    int randomB = random(0, 254);
    Serial.print("randomLed = ");
    Serial.println(randomLed);
    Serial.print("randomR = ");
    Serial.println(randomR);
    Serial.print("randomG = ");
    Serial.println(randomG);
    Serial.print("randomB = ");
    Serial.println(randomB);
    
    ShiftPWM.SetRGB(randomLed, randomR, randomG, randomB);
    randomTimer = 0;
  }
  
}

Also yesterday I swear changing "const bool ShiftPWM_invertOutputs = true;" between true and false and uploading would turn all the leds on or off but now its not doing anything.

Thanks for any incite.

 

[PaulStoffregen]

I tried ShiftPWM using its "ShiftPWM_RGB_Example" and the test hardware I built years ago with six 74HC595 chips and RGB LEDs.

I had the edit the example like this to make it compile.

 #define SHIFTPWM_NOSPI
 const int ShiftPWM_dataPin = 2;
 const int ShiftPWM_clockPin = 1;

At first glance, it seems to be working.



However, when I watch carefully I can see some slight "ghosting". It's difficult to photograph, but I was able to get this shot where you can see some light blue light coming from the last LED and some red and green from others, when only 1 LED is supposed to be on fully red.



I tried running at different speeds. The problem seems to go away if I run Teensy 4.1 at only 396 MHz, and it gets much worse if I overclock to 720 MHz. So my guess is the delays we currently have in the code might not be quite right.

 

[cfredisded]

Hey Paul thanks for the clarification. I got it working, ended up being a soldering issue. But now I'm having another problem that might be software related.
Basically I cant turn on led 24 without turning on led 23.

    ShiftPWM.SetRGB(8, 150, 150, 150); //turnes on 4 leds (23,24,25,26)
    ShiftPWM.SetRGB(8, 0, 150, 150); //turnes on 2 leds (25,26)
    ShiftPWM.SetOne(23,150); //turnes on 1 led (23)
    ShiftPWM.SetOne(24,150); //turnes on 2 leds (23,24)

maybe this is related to the ghosting?

Here's my full code in case its relevant.

#include <ShiftIn.h>

// Init ShiftIn instance with 3 chips
ShiftIn<2> shift;



// You can choose the latch pin yourself.
const int ShiftPWM_latchPin=9;

#define SHIFTPWM_NOSPI // ** uncomment this part to NOT use the SPI port and change the pin numbers. This is 2.5x slower **
const int ShiftPWM_dataPin = 25;
const int ShiftPWM_clockPin = 10;

// If your LED's turn on if the pin is low, set this to true, otherwise set it to false.
const bool ShiftPWM_invertOutputs = true;

// You can enable the option below to shift the PWM phase of each shift register by 8 compared to the previous.
// This will slightly increase the interrupt load, but will prevent all PWM signals from becoming high at the same time.
// This will be a bit easier on your power supply, because the current peaks are distributed.
const bool ShiftPWM_balanceLoad = true;

#include <ShiftPWM.h>   // include ShiftPWM.h after setting the pins!

// Here you set the number of brightness levels, the update frequency and the number of shift registers.
// These values affect the load of ShiftPWM.
// Choose them wisely and use the PrintInterruptLoad() function to verify your load.
unsigned char maxBrightness = 100;
unsigned char pwmFrequency = 75;
unsigned int numRegisters = 6;
//int numRGBleds = numRegisters*8/3;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  
  // declare pins: pLoadPin, clockEnablePin, dataPin, clockPin
  shift.begin(3, 4, 2, 5);
  

  // Sets the number of 8-bit registers that are used.
  ShiftPWM.SetAmountOfRegisters(numRegisters);
  // SetPinGrouping allows flexibility in LED setup. 
  // If your LED's are connected like this: RRRRGGGGBBBBRRRRGGGGBBBB, use SetPinGrouping(4).
  ShiftPWM.SetPinGrouping(1); //This is the default, but I added here to demonstrate how to use the funtion  
  ShiftPWM.Start(pwmFrequency,maxBrightness);

}

void displayValues() {
  // print out all 16 buttons
  for(int i = 0; i < shift.getDataWidth(); i++)
    Serial.print( shift.state(i) ); // get state of button i
  Serial.println();
}

void loop() {
  // put your main code here, to run repeatedly:
  if (shift.update()){
    // read in all values. returns true if any button has changed
    displayValues();
  }
  if (shift.state(11) == 0){ //button 7
    ShiftPWM.SetRGB(7, 150, 150, 150); 
  }
  else{
    ShiftPWM.SetRGB(7, 0, 0, 0); //button 7
  }
  if (shift.state(13) == 0){ //button Q
    ShiftPWM.SetRGB(8, 150, 150, 150); //turnes on 4 leds (23,24,25,26)
    //ShiftPWM.SetRGB(8, 0, 150, 150); //turnes on 2 leds (25,26)
    //ShiftPWM.SetOne(23,150); //turnes on 1 led (23)
    //ShiftPWM.SetOne(24,150); //turnes on 2 leds (23,24)
  }
  else{
    ShiftPWM.SetRGB(8, 0, 0, 0); //button Q
  } 


}

*edit* Actually having it at 396 MHZ seems to fix the issue