ConTemp
Contact Patch Temperature Sensor System
Provide a motorcycle operator with continuously updated information about tire surface temperature and lean angle safety.
Overview
- Embedded firmware for the Contact Patch Temperature Sensor System (ConTemp) motorcycle accessory.
- Targets Arduino Nano Every. Sketch drives:
- MLX90614 infrared (IR) sensor for front-tire surface temperature (I²C on A4/A5).
- BME280 for ambient temperature (shares the I²C bus).
- SPI color LCD (Adafruit ST77xx-compatible) showing color-coded status lines.
Primary Components (Prototype)
- IR temperature sensor
- Directed to the front tire of the motorcycle in order to detect the surface temperature of the front tire. Suggested mounting locations: (1) radiator guard, (2) exterior surface of front-most outer fairing, (3) fork tube (if line-of-sight to tire surface), (4) exterior surface of cowl.
- Minimum effective characteristics:
- D:S ≥ 12:1
- FOV ≤ 5-10°
- Spectral range: 8-14 µm
- Resolution ≤ 0.5°C
- Emissivity adjustable (0.8 - 1.0)
- IP65 (or better)
- Ambient temperature sensor
- Preferably mounted at a location that minimizes the influence of engine and exhaust heat and wind on ambient temperature readings. Suggested mounting locations: (1) interior surface of an outer fairing, (2) underside of seat (if sufficient distance from exhaust system/muffler), (3) subframe proximate to rear suspension.
- Microcontroller
- Arduino Nano Every recommended for smaller form factor.
- Preferably mounted on an interior surface of a fairing or behind the LCD display.
- LCD display
- Preferably mounted on the handlebars, handlebar clamp, or steering stem nut.
Method of Operation
- Outputs of the IR temperature sensor and ambient temperature sensor are inputs into the Arduino microcontroller.
- Microcontroller calculates and outputs values on a tire temp line and an ambient temp line to display on the LCD display.
- Tire temp line: carries values indicative of the temperature at the surface to which the IR temperature sensor is directed (i.e., front-tire surface temperature).
- Ambient temp line: carries values indicative of the ambient temperature of the motorcycle’s current operating environment.
- Microcontroller calculates primary display value corresponding to (approximate) tire surface temperature based on multiple samples received on the IR sensor (“tire temp”) line.
- Primary display value refreshed at 500ms intervals.
- Primary display value derived based on:
- Passthrough filter applied to each sample received on IR temp sensor line. Samples not within a reasonable range are discarded.
- Samples are timestamped on arrival, discarded when stale or replaced by fresh sample.
- Samples within a window are assigned respective weights based on corresponding timestamps.
- Exponential smoothing algorithm using weighted samples within the window applied so primary display value is gradually updated as tire surface temp meaningfully changes.
- Microcontroller calculates secondary display value corresponding to (approximate) ambient temperature based on multiple samples received on the ambient temp line.
- Secondary display value refreshed at 1000ms intervals.
- Secondary display value derived based on:
- Passthrough filter applied to each sample received on ambient temp line. Samples not within a reasonable range are discarded.
- Samples are timestamped on arrival, discarded when stale or replaced by fresh sample.
- Samples within a window are assigned respective weights based on corresponding timestamps.
- Exponential smoothing algorithm using weighted samples within the window applied so secondary display value is updated when ambient temp meaningfully changes.
- Microcontroller staggers updates to primary display value and secondary display value.
- Microcontroller instructs the LCD display to display primary value corresponding to tire temp line in one of:
- Red: 90℉ ≤ first value
- Indicates tire grip at the contact patch is too low to maintain traction during countersteering or emergency braking.
- Yellow: 90℉ < first value ≤ 130℉
- Indicates conservative countersteering may be utilized, but increased risk of traction loss at significant lean angles or abrupt emergency braking.
- Green: 130℉ < first value ≤ 185℉
- Indicates optimal surface temperature to maintain tire grip at the contact patch.
- Red: 185℉ < first value
- Indicates tire surface temperature at or near overheating state likely to cause reduced tire grip at the contact patch.
- Microcontroller instructs the LCD display to display secondary value corresponding to ambient temp line in one of:
- Red: 40℉ ≤ second value
- Indicates ambient temperature is low enough to reduce tire grip at the contact patch in most conditions.
- Yellow: 40℉ < second value ≤ 60℉
- Indicates ambient temperature is low enough tire grip at the contact patch may be reduced in some conditions.
- Green: 60℉ < second value ≤ 100℉
- Indicates optimal ambient temperature to maintain tire grip at the contact patch.
- Red: 100℉ < second value
- Indicates ambient temperature is high enough to reduce tire grip at the contact patch in most conditions (high ambient temperature causes air expansion inside the tires).
Hardware Pin Configuration
| Function |
Nano Every Pin |
Peripheral Pin |
| I²C SDA |
A4 |
MLX90614 SDA, BME280 SDA |
| I²C SCL |
A5 |
MLX90614 SCL, BME280 SCL |
| LCD SPI Clock |
D13 (SCK) |
Display CLK |
| LCD SPI MOSI |
D11 (MOSI) |
Display DIN/MOSI |
| LCD Chip Select |
D10 |
Display CS |
| LCD Data/Command |
D9 |
Display DC |
| LCD Reset |
D8 |
Display RST |
Power: 5 V tolerant variants.
Logic
Overview
SensorChannel — filtering, smoothing, and update-period management.Display — wraps an Adafruit ST77xx display over hardware SPI.src/main.cpp — Arduino setup/loop, real sensor drivers, and thresholds.
- Smoothing constants and thresholds are configurable via
src/main.cpp to fit
different tire compounds and environments.
Firmware
- Samples both sensors every 100 ms.
- Rejects samples outside configurable bounds.
- Applies exponential smoothing to improve accuracy of displayed values.
- Updates the tire temp line every 500 ms and the ambient temp line every 1000 ms.
- Draws two visually distinct text tiles on the LCD so the rider can quickly glance at the status:
- Large (primary) text tile displays data from tire temp line. Displayed above static “Tire Temp” label.
- Smaller (50%) text tile displays data from ambient temp line (ambient temp intended only as a supplement to tire temp). Displayed above static “Ambient” label.
- Color outputs that follow thresholds to enhance readability.
Implementation
The sketch initializes both sensors, draws the display once, and then
refreshes display each time one of the channels produces a new filtered value.
Required Arduino Libraries
- Adafruit MLX90614
- Adafruit BME280
- Depends on: (1) Adafruit Unified Sensor, (2) BusIO
- Adafruit GFX
- Adafruit ST7735
- Adafruit ST7789
Build / Flash
- Install
Arduino megaAVR board package; select applicable board, e.g., Arduino Nano Every.
-
To compile via CLI:
arduino-cli compile --fqbn arduino:megaavr:nona4809
arduino-cli upload --fqbn arduino:megaavr:nona4809 -p /dev/ttyUSB0
- Boot diagnostics observable via Serial Monitor @ 115200 baud.
- Detection/initialization of sensors and display.
Notes
- If either sensor fails to initialize, the firmware halts and prints an error
over Serial so bad data doesn’t reach the display.
- BME280 is probed at addresses
0x76 and 0x77; adjustable via src/main.cpp
for custom breakouts.
Planned Features
- User-configurable thresholds
- Single indicator for estimated tire grip, aggregates and weights samples from both input lines.
- Quality control/accuracy checks for IR temperature sensor so primary display value avoids presenting stale or inaccurate information.
License
- This repository is publicly viewable for portfolio purposes only. The code is proprietary.
- Copyright © 2025 Phaethon Order LLC. All rights reserved.
- Contact admin@phaethonorder.com for licensing or reuse requests.
See LICENSE for terms.
Questions or support: admin@phaethonorder.com.