Minimum hardware required for the "pancake board"

• MCU eval board
  • ST NUCLEO-F413ZH OR Adafruit Grand Central M4 Express
• LCD Display with buttons and RGB LED
  • Pico Display Pack from Pimoroni
  • Note: the application will run - albeit with no UI - if no LCD is connected to the MCU
• Serial EEPROM (I2C)
  • Sparkfun 64K EEPROM
  • Note: The AJAX application will fail its POST test if no EEPROM is connected.
• Temperature sensor: 10K 3950 Ohm NTC Thermistor
  • From Amazon
  • Note: The application will run - albeit with an active no-temperature-sensor alert - if no temperature sensor is connected.
• 10K Ohm resistor (for the temperature circuit)

Heating Element and Fan

Since the Heating and Fan control is open loop at the electrical level, not connecting a heater and fan does not prevent the application from running.

• Any variable capacity heating element that is controllable via 3.3V PWM signal can be used.
• Temperature safety feedback. A single normally high 3.3V Digital IO feedback to the MCU. The safety circuit should assert (pull low) the IO signal when the heating element exceeds its high temperature limit. Once the htemperature's is within 'safe' limits, the circuit should de-assert (pull high) the IO signal.
• Any variable speed fan that is controllable via 3.3V PWM signal can be used.