Reflow Oven Controller

The example that has to be Arduino. A MAX31855 on SPI, a profile clock, and a control loop tight enough that nobody wants it going through a network stack. The profile is the lead-free one everyone starts from: ramp to 150 C over ninety seconds, soak there to three minutes, ramp to 245 C, then off. The chart is the point of the screen. A reflow that missed its soak is obvious on a curve and invisible in a number, and the chart is also why this cannot be an ESPHome design - ESPHome has no chart widget. Control is bang-bang with a 2 C band. An oven has minutes of thermal lag, so anything cleverer is pretending to a precision the element does not have. On an STM32F407, which is the board to pick when the loop matters more than the network.