wire the MAX31856 and read a value over SPI

[kendrick]

What to build

The MAX31856 breakout sits on the breadboard beside the ESP32, wired over SPI, and returns a number. Any number. Correctness comes in the next ticket; this one is about the bus talking.

Dupont jumpers only, no soldering. MOSI, MISO, CLK and CS between the two boards, plus 3.3V and ground, following the breakout's own pinout rather than a generic diagram.

With no thermocouple attached the amplifier will report a fault or an implausible reading, and that is the expected result here. What matters is that ESPHome logs show the chip responding rather than silence or a bus error.

Acceptance criteria

• SPI plus power and ground are wired per the breakout's pinout
• ESPHome logs show the MAX31856 responding rather than a bus timeout
• The breadboard sits on a heat-safe surface, a couple of feet from where the plume will be
• No soldering was required

Blocked by

• flash the ESP32 and get it discovered by Home Assistant #12