I found a crazy bug in the unofficial Arduino support for the RP2040 v 4.01!
This is a strange tale... I've been using the excellent Raspberry Pi Pico Arduino Core , managed by Earle F. Philhower III, from its beginnings. It has been recently updated to support the new Pico2 and RP2350. As part of my preparations for testing the new Pico2 (received it yesterday), I was playing with some old microcontroller benchmarks. When I tried a Whetstone benchmark in the old Pico the program just stopped somewhere in the middle of the calculations, and here starts the tale. double X; // declared here so the multiplication is not removed by optimization void setup() { pinMode(LED_BUILTIN, OUTPUT); digitalWrite(LED_BUILTIN, LOW); double T = millis(); X = -1.3 * T; digitalWrite(LED_BUILTIN, HIGH); } void loop() { delay(100); } This code forces the bug!