The LazyDragon Oculus-16 analog IR sensor array is a 16-channel reflective infrared line-sensor board. Its 16 QRE1113GR sensors are multiplexed through a 74HCT4067 16:1 analog mux down to a single analog output, so a host MCU can read all 16 channels while leaving almost every pin free for motors, encoders, and control.
This page covers the hardware at a glance. For the code walkthrough see
MANUAL.md; for troubleshooting see DEBUG.md.
Each of the 16 sensing positions is a QRE1113GR reflective IR opto-sensor: an
infrared emitter paired with a phototransistor. The emitter bounces IR off the
surface below; the phototransistor current rises when the surface is
reflective and falls when it is dark. The 16 phototransistor outputs feed the
inputs (Y0..Y15) of a 74HCT4067PW 16:1 analog multiplexer, whose common
output (Z, routed to net C0) is the board's only analog signal. Four select
lines (S0..S3) choose which sensor is presented on C0, so the board
presents 16 channels through a 7-wire interface. All thresholding and
calibration happen in firmware.
The board is laid out as two wings of eight sensors flanking a central mux, with mounting holes designed for a front-mounted line-follower. Wiring is symmetric; if the array is mounted mirrored, channel order is simply reversed in firmware.
- 16 channels on one analog pin. A 74HCT4067 16:1 mux collapses sixteen sensor readouts into a single ADC input plus four digital selects.
- Sensor-per-channel gain matching easy in firmware. Every channel has its own 47 kΩ load, so each can be normalized independently.
- Emitter-pair sharing. Emitters are wired in series pairs with one 150 Ω current-limiting resistor per pair — lower part count, matched brightness.
- Compact, low-cost interface. Seven wires (GND, +5V, S0..S3, C0) carry the whole array; an 8-pin 1.0 mm FPC is provided for a tidy ribbon cable.
- Board-level status LEDs. Two onboard yellow LEDs for power/activity indication.
| Spec | Value |
|---|---|
| Sensor | 16x QRE1113GR reflective IR opto-sensor |
| Channels | 16 (Y0..Y15), multiplexed to one analog output |
| Multiplexer | 74HCT4067PW-Q100J, single-pole 16-throw (16:1) analog |
| Mux on-resistance | ~80 Ω typical at VCC = 4.5 V |
| Select lines | 4 (S0..S3), TTL level (74HCT) |
| Common output | Z (net C0), analog 0..VCC |
| Board size | 154.12 mm x 29.23 mm |
| Mounting holes | 2, spaced 91.000 mm apart |
| Emitter drive | emitters in series pairs, one 150 Ω per pair (8 total) |
| Phototransistor load | 16x 47 kΩ |
| Decoupling | 1x 1 µF |
| Indicators | 2x yellow LED, 150 Ω each |
| Interface | 7-pin 2.54 mm header H2 + 8-pin 1.0 mm FPC CN1 |
| Emitter peak wavelength | 940 nm |
| Sensor operating temperature | -40 to +85 °C |
| Supply | +5 V |
Mechanical drawings, assembly images, the schematic, the BOM, and the
manufacturing package are in assets/, datasheets/, and fabrication/.
oculus16/
├── README.md
├── MANUAL.md
├── DEBUG.md
├── CHANGELOG.md
├── LICENSE # hardware — CC BY-NC-SA 4.0
├── LICENSE-CODE # firmware — PolyForm Noncommercial 1.0.0
├── COMMERCIAL-LICENSE.md
├── assets/ # images, schematic, BOM
├── datasheets/ # vendor datasheets
├── fabrication/ # gerbers, drill, pick-and-place
└── code/ # firmware / source
- Power the board from +5 V and GND (via
H2or theCN1FPC). - Connect the four select lines
S0..S3and the common analog outputC0to your MCU (see Pinout / wiring). - Mount the array a small, fixed distance above the surface; keep the sensing gap consistent across all 16 sensors.
- Open
code/oculus_16.inoin the Arduino IDE (ATmega328P / Arduino Nano target) and flash it. - On boot, sweep the array across the line for four seconds so it can calibrate; it then streams 16 calibrated channels plus position and status over Serial at 115200 baud.
The sketch scans all 16 mux channels continuously from the ADC-complete
interrupt — the main loop never calls analogRead().
The reader cycles the mux and reads one channel at a time. The select lines map directly to the mux channel:
| S3 | S2 | S1 | S0 | Channel |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | Y0 |
| 0 | 0 | 0 | 1 | Y1 |
| ... | ... | ... | ... | ... |
| 1 | 1 | 1 | 1 | Y15 |
Key configuration constants at the top of code/oculus_16.ino:
| Constant | Default | Meaning |
|---|---|---|
NUM_SENSORS |
16 |
Channels scanned, mux 0..15. |
IS_BLACK_LINE |
true |
true for a dark line on a light floor. |
ON_THRESHOLD |
500 |
Calibrated value (0..1000) above which a channel is "on line". |
EDGE_SENSOR_COUNT |
2 |
A cluster confined to this many outer sensors is reported as an edge. |
POSITION_SCALE |
1000 |
Integer position scale factor. |
SENSOR_WEIGHT[] |
-15..+15 |
Symmetric weights used by the centroid. Flip if mirrored. |
MUX_SHIFT / MUX_MASK |
0 / 0x0F |
Mux select S0..S3 on A0..A3 (PORTC 0..3). |
MUX_COMMON |
4 |
ADC channel of the mux common output (A4). |
See MANUAL.md for the full function reference.
H2 — 7-pin 2.54 mm header
| Pin | Function |
|---|---|
| 1 | GND |
| 2 | S3 |
| 3 | S2 |
| 4 | S1 |
| 5 | S0 |
| 6 | C0 (mux common analog output) |
| 7 | +5 V |
CN1 — 8-pin 1.0 mm FPC (KH-CL1.0-H2.5-8PIN)
| Pin | Function |
|---|---|
| 1 | S3 |
| 2 | S2 |
| 3 | S1 |
| 4 | S0 |
| 5 | C0 |
| 6 | GND |
| 7 | +5 V |
| 8 | +5 V |
Host MCU wiring (Arduino Nano / ATmega328P, as used by code/oculus_16.ino)
| Signal | Nano pin | ATmega |
|---|---|---|
S0 |
A0 |
PC0 |
S1 |
A1 |
PC1 |
S2 |
A2 |
PC2 |
S3 |
A3 |
PC3 |
C0 |
A4 |
ADC4 |
| GND | GND | — |
| +5 V | +5V | — |
The mux enable E# is tied to GND on the board, so no host pin is needed.
A6/A7 are analog-only and cannot drive the select lines.
MANUAL.md— usage and code/function reference.DEBUG.md— expected behavior and troubleshooting.CHANGELOG.md— version history.COMMERCIAL-LICENSE.md— commercial licensing and royalties.- Schematic and BOM:
assets/ - Manufacturing files (gerbers, drill):
fabrication/
This project is source-available, not open source.
- Hardware (PCB, schematic, assets) —
LICENSE· CC BY-NC-SA 4.0: free for personal and non-commercial use with attribution; commercial use requires a separate license. - Firmware (
code/) —LICENSE-CODE· PolyForm Noncommercial 1.0.0: free for non-commercial use.
Commercial use requires a paid license (royalty + attribution). See
COMMERCIAL-LICENSE.md or contact
contact@lazydragon.club.
The design and firmware are provided "as is", without warranty of any kind. LazyDragon Pvt Ltd is not liable for any damages arising from their use. You use this project at your own risk; verify all safety and certification requirements before any product use.
These licenses are non-commercial, so this is not an OSI open-source or OSHWA-certified open-hardware release.
Background. LazyDragon is a startup building open hardware. This board is one of its earlier builds — designed from scratch in high school — now released to the community alongside newer designs. These earlier releases are published under source-available, non-commercial licenses.