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Sonar Chronicles, Part 1: First Blood, Blinking LEDs, and Hardware Timer Pain 🛠️🔥

By Admin•Jun 17th, 2026•2 min read

The packages have finally arrived, the breadboard is unpacked, and the soldering iron is hot. Naturally, step number one was to test the ESP32 board itself and see how it plays with TinyGo.

I flashed a basic test script, and... it’s alive! The onboard LED is blinking exactly as it should. The classic hardware "Hello, World!" is officially complete. But the moment I tried to take a step toward the actual fish finder logic, the compiler brought me right back down to earth.

# The Brick Wall: Where Is My Hardware Timer? 🛑

For a sonar system, relying on a hardware timer rather than a software-based one is absolutely critical.

  • Why a software timer won't work: Software timers depend heavily on the operating system and the runtime environment. If the runtime garbage collector kicks in or a micro-pause occurs in the execution thread, our measurement accuracy goes out the window.
  • The real-world impact: A fish finder measures the precise round-trip time it takes for an ultrasonic pulse to hit the riverbed and bounce back. Sound travels through water incredibly fast—roughly 1,500 meters per second. A discrepancy of just a few milliseconds caused by runtime jitter would turn our depth chart into completely random noise. I need nanosecond-level accuracy enforced directly at the silicon level.

And that’s exactly where TinyGo threw a wrench in the gears. When trying to initialize hardware timer zero for the esp32-generic target, the compiler bluntly returned: undefined.

# What Went Wrong and Plan B 🧭

Most likely, I missed a specific compilation flag, or the current TinyGo standard library mapping for this particular board doesn't fully expose the peripheral hardware timers yet. Next up on my to-do list is digging deep into the official documentation and the TinyGo source files.

However, if I can't resolve this through the standard library out of the box, it’s time to bring out the heavy artillery.

My Plan B is to interface directly with MMIO (Memory-Mapped I/O) and manipulate the timer registers manually. To avoid reinventing the wheel entirely in pure Go—where peripheral support for the ESP32 can be hit or miss—I'm planning to leverage a traditional FFI (Foreign Function Interface) pattern. I’ll write a lean, low-level driver in C to toggle the hardware timer via processor registers, then bridge those raw metrics back into my Go runtime.

What started as engineering curiosity is quickly turning into hard-core, bare-metal hacking. Stay tuned—things are about to get real! 💻☠️