From 41790316eb06a02b909b99df2c4fd5c0bc855445 Mon Sep 17 00:00:00 2001
From: James Munns <james@onevariable.com>
Date: Thu, 2 Jan 2025 18:23:34 +0100
Subject: [PATCH] Add note for nRF52840-dk board details

---
 examples/nrf52840/src/bin/pwm_sequence_ws2812b.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/examples/nrf52840/src/bin/pwm_sequence_ws2812b.rs b/examples/nrf52840/src/bin/pwm_sequence_ws2812b.rs
index 751cf44252..6f04a53b8e 100644
--- a/examples/nrf52840/src/bin/pwm_sequence_ws2812b.rs
+++ b/examples/nrf52840/src/bin/pwm_sequence_ws2812b.rs
@@ -14,6 +14,16 @@ use {defmt_rtt as _, panic_probe as _};
 // https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf.
 // This demo lights up a single LED in blue. It then proceeds
 // to pulsate the LED rapidly.
+//
+// /!\ NOTE FOR nRF52840-DK users /!\
+//
+// If you're using the nRF52840-DK, the default "Vdd" power source
+// will set the GPIO I/O voltage to 3.0v, using the onboard regulator.
+// This can sometimes not be enough to drive the WS2812B signal if you
+// are not using an external regulator. If you set the board to "USB" power
+// instead (and provide power via the "nRF USB" connector), the board will
+// instead power the I/Os at 3.3v, which is often enough (but still out of
+// official spec) for the WS2812Bs to work properly.
 
 // In the following declarations, setting the high bit tells the PWM
 // to reverse polarity, which is what the WS2812B expects.