Reader map
What this page proves
Traceable vehicle data acquisition from one raw CSV. Start here for the build, question, measurement, and closeout proof.
What we are making
A low-cost OBD-II logging setup: Android phone or laptop, Bluetooth ELM327 adapter, safe cable routing, and CSV export.
Question answered
Can a cheap adapter log four useful vehicle channels for 20 minutes without missing units or losing traceability?
What will be measured
timestamp_s, rpm, speed_mph, coolant_C, and voltage_V from one raw CSV.
Proof that closes it
02_channel_list.txt, 02_install_photo.jpg, 02_raw_drive_log.csv, 02_file_hash.txt, four charts, and 02_summary.pdf.
The car already has sensors. The OBD-II adapter asks the car for readings, then saves them to a CSV. The project proves the charts came from that raw file, not hand-picked points.
Words you need
Project terms
| Term | Meaning on this page |
|---|---|
| OBD-II | The car diagnostic connector. |
| PID | Request code for one vehicle reading. |
| ELM327 | Common low-cost adapter chip. |
| CSV | Plain-text table file. |
| Sample rate | How often a channel updates. |
| Raw data | Untouched file saved before charts. |
| Coolant temperature | Engine coolant reading. |
| Voltage | Electrical system or adapter reading. |
| Timestamp | Time value for each row. |
| Channel | One measured signal. |
Capstone framing
Objective, requirements, constraints
| Type | Specific requirement |
|---|---|
| Objective | Log a clean four-channel drive file. |
| R1 | RPM, speed, coolant temperature, voltage. |
| R2 | Twenty-minute route. |
| R3 | At least 1,000 rows per channel. |
| R4 | No gap longer than 5 s. |
| R5 | Units in every column. |
| R6 | Raw file hash before charts. |
| Safety | Driver never handles device while moving. |
Section 01 · Concept
Data source and approach
Every US car since 1996 has a socket under the dash called the OBD-II port. The car's computer answers questions through it, one reading at a time. This build saves those answers to a file, untouched, and turns them into charts. Total hardware cost: under $80.
What it is
Parts and procedure
The parts are small: one adapter, one cable, zip ties, and a laptop. All the engineering is in the procedure. Check the readings while parked. Drive a planned route. Save the raw file before making any chart.
Every chart comes from the one saved file. Anyone can trace any point on a chart back to a time-stamped line in that file.
Actual principle used
Traceable vehicle data acquisition from one raw CSV
Reading sensors, saving data, and charting it over time. Each one produces a real file or picture you can show.
Acquisition
OBD-II PID polling
Logging
raw CSV
Presentation
4 charts
Evidence
4 items
Section 04 · Sequence
Build sequence and gates
The order is: install, check, drive, chart. Each step ends at a gate — a checkpoint that names the proof needed before moving on.
Sequence
Build steps
Connect. Plug in the ELM327 and pair with the adapter's default PIN (usually 1234 or 0000). On a laptop, bind the adapter's Bluetooth serial (SPP) port — Windows lists it as an outgoing COM port; Linux and macOS expose an rfcomm/tty device — and confirm the logging software connects on it. Car Scanner (free) or Torque Pro ($4.95) log to CSV on Android; python-OBD with a 1 s polling loop writes a timestamp plus four channels per row.
Route. Fix the 3 ft extension away from the pedals with zip ties, and label both cable ends (port end, adapter end) with the printed tape labels so the routing photo shows identified cabling.
Document. Seat the logger in the passenger footwell, strap it down with the Velcro strap so it stays put under braking, and photograph the install.
Verify. Run the parked idle test; list supported channels and confirm all four target readings return plausible values.
Drive. Start logging while parked at the route origin, drive the defined 20-minute city/highway route to raw CSV, and stop logging after parking at the end. The driver leaves the logging device untouched while the vehicle moves; a passenger handles any mid-drive monitoring.
Chart. Plot RPM, speed, coolant temperature, and system voltage from the raw CSV.
Package. Export CSV, charts, photo, and channel list together, then unplug the adapter — the OBD-II port stays powered with the ignition off, and a plugged-in adapter slowly drains the battery.
Acceptance gates — owner: Kohler
Acceptance gates for the data package
Risk, judging, and closeout
What can fail and how the result is judged
What could go wrong
| Risk | Control | Failure action |
|---|---|---|
| Driver distraction | Start/stop parked; passenger handles checks. | Discard run if driver touched device. |
| Cable near pedals | Route along sill and tie at three points. | Reroute and retake photo. |
| Unsupported PID | Parked channel test first. | Choose supported alternate. |
| Dropped connection | Charged device and one adapter. | Repeat route. |
| Edited raw file | Hash before charts. | Restart from raw file. |
How the result will be judged
| Check | A-level result | Not acceptable |
|---|---|---|
| Traceability | Every chart point traces to 02_raw_drive_log.csv. | Copied values. |
| Completeness | Four channels, units, timestamps, row count. | Missing units or short run. |
| Safety | Install photo shows clear pedals. | Loose device. |
| Capstone scale | Reusable logger/dashboard extension. | Single screenshot. |
Data package
Exact closeout filenames
- 02_channel_list.txt
- 02_install_photo.jpg
- 02_raw_drive_log.csv
- 02_file_hash.txt
- 02_rpm_chart.png
- 02_speed_chart.png
- 02_coolant_chart.png
- 02_voltage_chart.png
- 02_summary.pdf
Senior capstone readiness
Current status: build plan; data pending. Standalone level is B; A-level needs reusable dashboard, sample-rate characterization, plausibility checks, and automated reporting.
Definition of done
- Parked channel list is saved.
- Raw CSV has units and timestamps.
- Hash is recorded before charts.
- Four charts and summary come from raw file.
Section 02 · Method
Signal path and pre-drive checks
The signal path is short: the car's computer sends readings out the socket, and the adapter passes them by Bluetooth to the laptop. Before the car moves, three things get checked: the readings work while parked, the cable is tied away from the pedals, and the route is planned.
Hardware and data path · live model
Signal path: ECU → OBD-II port → 3 ft extension → ELM327 → Bluetooth → logging device. Install photo is gate PHOTO-1.
Sampling reality
One to two samples per second, per channel
4 channels round-robin → 1–2 Hz per channel
20 min drive → ~1,200–2,400 rows per channel in the CSV
A cheap adapter asks for one reading at a time, so four readings share the line. Each one updates about once or twice a second. That is plenty for watching trends. Each chart states its own measured rate.
These speeds assume a 2008-or-newer US car and a decent adapter. Older cars answer about half as fast. The parked test measures the true rate before the drive.
Voltage comes from the car's computer when the car supports that reading. If not, the adapter reads voltage at its own pin instead. The channel list records which source was used.
Pre-drive checks
Parked verification
The parked test lists which readings this car supports and proves the link works. Zip ties hold the cable away from the pedals. A strap holds the laptop in place. Both get photographed. The raw file gets saved before any chart is made.
Channel check
parked
Route
20 min city+hwy
Cable
clear of pedals
Raw file
first
Zoo / SolidWorks — build this model
Layout sketch
This build has no parts to machine, so the CAD job is small. Draw the driver's footwell as one layout sketch: the socket, the adapter, the cable run, and the tie-down points. Its only purpose is to plan where the cable rides so it stays clear of the pedals.
Produce one drawing from it: the cable-routing diagram, with the tie points dimensioned off the seat rail. Print it, follow it during the install, and photograph the result — the photo closes gate PHOTO-1. A working model of this build is embedded just below, and its STL download opens in SolidWorks, Onshape, or FreeCAD.
Runs in: Zoo (free — its Zookeeper agent builds from this prompt, edits by conversation, and answers design questions) · SolidWorks LEO · or by hand from the list above.
The Zoo file goes into the zoo-design-studio-projects folder shown at the top of Zoo’s Projects screen; the build then appears in the Projects list, dimensioned from this sheet. Paste the macro into SolidWorks (Tools → Macro → New) to export every drawing as a web image.
Model
layout sketch
Check
cable clearance
Drawing
routing diagram
Works on
any tier
Section 03 · Parts
Parts and cost
The hardware list is short and cheap. Both the adapter and the cable are off-the-shelf parts, and the laptop or phone is one already owned. One buying choice matters, and the note under the parts list explains it.
Bill of materials
Six line items, $30–80 total
| Item | Qty |
|---|---|
| Bluetooth ELM327-compatible OBD-II adapter | 1 |
| OBD-II extension cable, 3 ft | 1 |
| Laptop or Android phone for logging | owned |
| Zip ties | 10 |
| Velcro strap | 1 |
| Printed tape labels for cable ends | set |
| Parts total | $30–80 |
Buy a genuine v1.5 adapter or a $20–60 name-brand unit. Most adapters sold as “v2.1” are clones with broken readings. Spending near the top of the budget avoids a wasted evening.
Match the adapter to the device. Android phones and Windows laptops use regular Bluetooth. iPhones need a low-energy (BLE) model such as the Veepeak BLE+. Print the cable labels on a home printer.
Tools and environment
Tools and test route
Needed: a car with the socket, a safe 20-minute route with city and highway driving, and a logging app or a Python setup (Car Scanner is free; Torque Pro is $4.95). A camera takes the install photo, and a printer makes the labels.
Time
8–15 h
Cost
$30–80
Software
app or Python
Shop tools
cutters or scissors
Section 05 · Scope
Scope and next steps
This build records four engine readings at the slow speed a cheap adapter allows. The original file never gets edited. Later builds keep that same habit at much faster speeds.
Evidence package
Four deliverables
The raw file, the four charts, the install photo, and the channel list. One folder, one drive, charts drawn straight from the source.
Where it leads
Connection to build 01
The keep-the-raw-file habit carries into build 01, the jet-engine stand, which saves thrust and speed the same way. Later turbine tests use it too.