Ça peut être un problème d'alimentation en effet. Selon la datasheet une LED APA102 consomme 200mW soit 40mA sous 5V - j'avais en tête plutôt 60 - donc si tu as plusieurs bandeaux de 19 (disons 20 pour arrondir) LED, l'alim de 1A risque de ne pas suffire.
Essaye avec un seul bandeau pour voir si ça fonctionne.
Sinon, comme dit J-M-L, il est possible de ne pas les allumer au maximum. FastLED contient des instructions de gestion de la consommation. Je pense qu'elles fixent une brightness maximale en fonction de l'ampérage maximal que tu déclares.
Conseils issus de cette page :
Troubleshooting
Often when an LED strip is acting odd, or randomly, there's a power problem. Here are some things to check and try:
See if your animation works properly at a very low setBrightness level (e.g., "32", which is 1/8th brightness), but then goes nuts at higher brightnesses. If so: you're out of power.
See if your animation works properly on a very small number of LEDs, but then starts going nuts when you step up to a larger number. If so, you're out of power (or you have an out-of-RAM problem).
If your setup is USB-powered and having trouble, try powering your LED strips from an external (5v) power supply. Make sure to connect the Ground from the external power supply to the USB-based Ground. If your animation flickers and goes nuts when exclusively USB powered, but works fine with an external power supply, you were out of power.
Gestion de la consommation :
Managing power in FastLED
(introduced in FastLED3.1.1)
FastLED allows you to cap the power usage of your leds. There's two ways to set the max power draw you want.
The first is by specifying the voltage your leds will be running at and the maximum milliamps you want to draw:
// limit my draw to 1A at 5v of power draw
FastLED.setMaxPowerInVoltsAndMilliamps(5,1000);
The other is to specify the maximum draw you want in watts:
// limit my draw to 5W
FastLED.setMaxPowerInMilliWatts(5000);