Is MAX31865 RTD PT100 Temp Amplifier Compatible with Arduino Ecosystem?
Electrical Specifications
Always confirm pin assignments against the manufacturer datasheet before wiring.
Compatibility Overview
Industrial-grade platinum RTD resistance thermometer amplifier delivering high precision temperature readings.
Typical SPI Wiring Reference
Standard SPI signal names. This is a bus reference, not a pinout for this specific board — check the silkscreen and datasheet for its actual pin order.
Reference circuit only. A shifter is needed when the host and peripheral run at different logic levels — check both datasheets to confirm whether this applies to your pairing.
Technical Specification Matrix
| Feature / Attribute | Specification / Status |
|---|---|
| Hardware Protocol | SPI Bus / 3.3V |
| Bridge Required | NO |
| Border Router Needed | None |
| Hardware Capabilities & Peripherals | PT100 Platinum Temp (C) Resistance (Ohm) Fault Status Note: these entities come from the ESPHome configuration you flash — each one needs its matching component in that YAML before it appears. |
| Pairing Complexity | Advanced |
| Factory Reset Instruction | Press BOOT button while resetting. |
Wire, Flash, Adopt, Check
Wire it up
Follow the bus reference above. The host pins in the configuration are defaults — any free GPIO of the right kind will do, as long as the YAML names the pin you actually used.
Flash the configuration
Create a new device in the ESPHome dashboard (the Home Assistant add-on) and paste the configuration below into it, or save it as emb_esp32_max31865_ard.yaml and run esphome run emb_esp32_max31865_ard.yaml. The first flash goes over USB. If it is not detected, press BOOT button while resetting to put it in download mode. Every update after that is over the air.
Adopt it in Home Assistant
Settings → Devices & Services. A node on the same network shows up as a discovered ESPHome device within a minute of joining Wi-Fi; choose Configure and enter the API encryption key from your secrets.yaml. If discovery does not find it, add the ESPHome integration by hand with the node's IP address.
Check it works
The entities on this page appear under the device in Home Assistant and update at the configured interval. The ESPHome log (Logs in the dashboard, or esphome logs) reports the setup of each component and any bus scan results at boot.
ESPHome Configuration
Starting configuration for MAX31865 RTD PT100 Temp Amplifier on ESP32. Untested on hardware — verify wiring and pins against your own board.
# ESPHome configuration for MAX31865 RTD PT100 Temp Amplifier
# Host: ESP32. Pin numbers below are host-side defaults — any free
# GPIO will do, and you should change them to match your own wiring.
esphome:
name: emb_esp32_max31865_ard
friendly_name: "MAX31865 RTD PT100 Temp Amplifier"
esp32:
board: esp32dev
framework:
type: esp-idf
logger:
api:
encryption:
key: !secret api_encryption_key
ota:
- platform: esphome
password: !secret ota_password
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
spi:
clk_pin: GPIO18
mosi_pin: GPIO23
miso_pin: GPIO19
sensor:
- platform: max31865
name: "RTD Temperature"
cs_pin: GPIO5
reference_resistance: 430 ohm
rtd_nominal_resistance: 100 ohm
update_interval: 60s
Before you flash:
the !secret values come from your
secrets.yaml, and the GPIO numbers are host-side
defaults rather than properties of this part — change them to match how you actually wired it.
Report a Pinout Error or Submit Tested Code Snippets
Found a pin mapping quirk or built a custom ESPHome YAML driver for MAX31865 RTD PT100 Temp Amplifier? Submit a pull request or report corrections to our index.