Open Road Code

Documentation

Automotive Hardware I/O

Source: hardware_io/automotive/README.md

The hardware_io.automotive package contains low-level interfaces for automotive hardware. Code in this package owns device connections and raw device communication; it does not interpret vehicle data or implement application behavior.

Components

ELM327

elm327 communicates with ELM327-compatible diagnostic devices over a serial connection such as a Bluetooth RFCOMM device at /dev/rfcomm0.

from hardware_io.automotive.elm327 import Elm327Device

Layer Boundaries

  • hardware_io.automotive owns physical-device access and transport details.
  • protocols.obd2 owns OBD-II requests, normalized responses, and PID decoding.
  • controllers.automotive.obd2 coordinates devices and protocol models into vehicle state for applications.

Keeping these layers separate allows another OBD-II transport to reuse the protocol and controller code without depending on ELM327 command syntax.

Installation

Automotive and Bluetooth support are optional host features. On a Raspberry Pi 5, install both and configure the ELM327 RFCOMM binding with:

scripts/installers/host_setup.sh \
    --target rpi5 \
    --feature automotive \
    --feature bluetooth \
    --bluetooth-spp-address 12:34:5A:05:9C:54

The automotive feature installs pyserial. The Bluetooth feature installs the BlueZ utilities used to establish and persist the RFCOMM connection.

Decoded OBD-II Component Test

After the raw ELM327 component test succeeds, run the automotive controller test to request and decode live vehicle values:

python3 -m controllers.automotive.obd2.component_test.obd2_cli \
    --port /dev/rfcomm0

The controller test uses Elm327ObdAdapter to translate raw, header-enabled ELM327 output through protocols.can.CanFrame and into protocols.obd2.Obd2Response objects. It then uses Obd2Manager to decode supported PIDs and display values such as RPM, speed, temperatures, throttle position, and control-module voltage. Stop it with Ctrl+C.