user63297: I am making a custom wall-clock, and need the Arduino (Uno or Nano) to connect to a DS1302 real time clock module and a WS2811 LED chain.
So I’m using DS1302 for the clock, and FastLED for the lights. Individually these two libraries work fine, so I can either echo the time to the serial console, or I can drive the LEDs as I need.
But when I combine them there is some conflict happening and I get no LED output. The LED data goes over pin 6 and the clock uses pins 2,3,4 (these pins are customisable in code).
Even just adding a DS1302 initialisation to a working FastLED sketch causes no more LED output
#include <FastLED.h>
#include <DS1302.h>

#define NUM_LEDS 50
#define DATA_PIN 6

// Init the DS1302 - stops LEDs working
DS1302 rtc(2, 3, 4);

CRGB leds[NUM_LEDS];

void setup() { 
  FastLED.addLeds<WS2811, DATA_PIN, RGB>(leds, NUM_LEDS);
}

void loop() { 
  for (int i=0; i<NUM_LEDS;i++) {
    leds[i] = CRGB::Red;
  }
  FastLED.show();
  delay(100);
}

What are my troubleshooting steps - should I try alternative libraries, or could I dig into the libraries themselves and see what hardware resources they might be using?
I guess as both the lights and the clock probably operate over a serial protocol, it could be a conflict with the serial drivers - maybe both using the same time-critical operations.
Edit: inserted sketch which demonstrates the issue

user63297: I installed a library from within the IDE as StarCat suggested.
https://github.com/Makuna/Rtc
#include <FastLED.h>
#include <ThreeWire.h> 
#include <RtcDS1302.h>

#define NUM_LEDS 50
#define DATA_PIN 6

ThreeWire myWire(3,4,2); // IO, SCLK, CE
RtcDS1302<ThreeWire> Rtc(myWire);

CRGB leds[NUM_LEDS];

void setup() { 
   FastLED.addLeds<WS2811, DATA_PIN, RGB>(leds, NUM_LEDS);
   Rtc.Begin();
}

void loop() {
   RtcDateTime dt = Rtc.GetDateTime();

   for (int i=0; i<NUM_LEDS;i++) {
     leds[i] = CRGB::Red;
   }

FastLED.show();
delay(100);
}

I am able to get and use the time, and the LED output works.

63297: <p>I am making a custom wall-clock, and need the Arduino (Uno or Nano) to connect to a DS1302 real time clock module and a WS2811 LED chain.</p>

<p>So I’m using <a href="http://www.rinkydinkelectronics.com/library.php?id=5" rel="nofollow noreferrer">DS1302</a> for the clock, and <a href="https://github.com/FastLED/FastLED" rel="nofollow noreferrer">FastLED</a> for the lights. Individually these two libraries work fine, so I can either echo the time to the serial console, or I can drive the LEDs as I need.</p>

<p>But when I combine them there is some conflict happening and I get no LED output. The LED data goes over pin 6 and the clock uses pins 2,3,4 (these pins are customisable in code).</p>

<p>Even just adding a DS1302 initialisation to a working FastLED sketch causes no more LED output</p>

<pre><code>#include &lt;FastLED.h&gt;
#include &lt;DS1302.h&gt;

#define NUM_LEDS 50
#define DATA_PIN 6

// Init the DS1302 - stops LEDs working
DS1302 rtc(2, 3, 4);

CRGB leds[NUM_LEDS];

void setup() { 
  FastLED.addLeds&lt;WS2811, DATA_PIN, RGB&gt;(leds, NUM_LEDS);
}

void loop() { 
  for (int i=0; i&lt;NUM_LEDS;i++) {
    leds[i] = CRGB::Red;
  }
  FastLED.show();
  delay(100);
}
</code></pre>

<p>What are my troubleshooting steps - should I try alternative libraries, or could I dig into the libraries themselves and see what hardware resources they might be using?</p>

<p>I guess as both the lights and the clock probably operate over a serial protocol, it could be a conflict with the serial drivers - maybe both using the same time-critical operations.</p>

<p>Edit: inserted sketch which demonstrates the issue</p>
 63297: <p>I installed a library from within the IDE as StarCat suggested.</p>

<p><a href="https://github.com/Makuna/Rtc" rel="nofollow noreferrer">https://github.com/Makuna/Rtc</a></p>

<pre><code>#include &lt;FastLED.h&gt;
#include &lt;ThreeWire.h&gt; 
#include &lt;RtcDS1302.h&gt;

#define NUM_LEDS 50
#define DATA_PIN 6

ThreeWire myWire(3,4,2); // IO, SCLK, CE
RtcDS1302&lt;ThreeWire&gt; Rtc(myWire);

CRGB leds[NUM_LEDS];

void setup() { 
   FastLED.addLeds&lt;WS2811, DATA_PIN, RGB&gt;(leds, NUM_LEDS);
   Rtc.Begin();
}

void loop() {
   RtcDateTime dt = Rtc.GetDateTime();

   for (int i=0; i&lt;NUM_LEDS;i++) {
     leds[i] = CRGB::Red;
   }

FastLED.show();
delay(100);
}
</code></pre>

<p>I am able to get and use the time, and the LED output works.</p>
