‍Work in progress. Hardware and firmware are under active development and are not yet complete.

Precision reflow soldering controller for the Ninja Foodi DT200UK, built by MungerWare. Targets the STM32G0B1 and runs on FreeRTOS.

What it does

Thermal control

Drives three independently switchable heating zones (top quartz, bottom quartz, rear convection) with configurable ramp rate, target temperature, and hold tolerance. Two Type-K thermocouples and an oven cavity thermistor are averaged for the control input; any faulted sensor is automatically excluded. A hard over-temperature limit de-energises all elements and latches a fault regardless of the active profile.

Reflow profiles

Profiles define a sequence of temperature stages (preheat, soak, reflow, cool) with per-stage ramp rates and hold times. Profiles are stored on the onboard flash and can be loaded, edited, and triggered remotely.

Connectivity

A USB CDC interface exposes a REST API for profile management, live telemetry, and manual control. A CLI is available on the same port for terminal-based debugging and direct hardware access.

Power

Mains operation is fed by a RAC20 PSU at 24 V / 20 W. When mains is absent, the board operates as a USB Power Delivery sink and accepts whatever voltage the host negotiates — enough to run the full logic stack, sensors, fans, and communications for development and flashing without AC present. As a USB-PD source the board offers 5 V, 9 V, 12 V, and 20 V, all capped at 15 W.

Storage

64 MB of NOR flash is managed through a layered filesystem: a partition table in block 0 defines up to eight named partitions, each independently mountable via LittleFS. Files carry owner UIDs and Unix-style permission modes; UID 0 (System) bypasses all checks, while partitions, directories, and files can be marked read-only or hidden to protect system data from accidental damage via the API. Reads and writes have both synchronous and asynchronous variants; the async path accepts any FreeRTOS synchronisation primitive as a completion signal.

Cooling

Dual fan channels: an AC convection fan inside the oven cavity, and a DC board cooling fan with closed-loop speed control. Both are tachometer-monitored; a stall or out-of-range speed raises a fault.

Safety

This device controls mains-voltage heating elements. Over-temperature protection is enforced in firmware, but the last-resort cutoff is the fuse in the UK mains plug. Do not defeat it.

The board carries a header for a hardware emergency-stop button — ideally a very large, extremely red, normally-closed mushroom-head type. The signal is held low while the button is armed; pressing it breaks the circuit and immediately cuts power to all AC loads (heaters, fan, and light) at the hardware level, with no possibility of MCU override. This wiring convention also means a disconnected or broken cable is treated as a stop rather than a silent bypass. If no button is fitted, the header must be shorted with a jumper to allow normal operation.

Build

Prerequisites

ARM GNU Toolchain (arm-none-eabi-gcc)
CMake 3.22+
Ninja
Whisky, large

Compile

mkdir build && cd build
cmake .. -GNinja
ninja

Resources

Hardware design: https://oshwlab.com/trhosking/reflow-oven
Source documentation: https://munger.github.io/Reflow-Oven/
Function reference: Docs/ModuleRef.md