Sensor modules

AXS-013 — APDS-9251 RGB+IR color-sensor PMOD module

Catalog #13 in the AruviX sensor line, level L3 (I2C). Uses the APDS-9251-001 instead of the catalog's original TCS34725: no stock KiCad assets exist for the TCS34725, and the APDS-9251 teaches the same color-sensing lesson (four channels, gain/integration control, threshold interrupt) from stock symbols and footprints.

Level L3 ERC clean DRC clean Fab package 10 components

3D render of the AXS-013 PCB — Rendered from the PCB layout. No physical board has been manufactured.

Circuit review & bench-test guide →

Components#

Every placed component, with the reason it is on the board. Extracted directly from the schematic, so this cannot drift from the design.

Ref	Value	What it does on this board	Part number	Footprint
`C1`	100nF 16V X7R	U1 VDD high-frequency decoupling	`GRM188R71C104KA01D` Murata	`C_0603_1608Metric`
`C2`	1uF 10V X7R	U1 VDD bulk decoupling	`GRM188R71A105KA61D` Murata	`C_0603_1608Metric`
`J1`	PMOD PLUG 2x6	PMOD peripheral plug (Digilent spec 1.2)	not selected generic	`PinHeader_2x06_P2.54mm_Horizontal`
`JP1`	SDA PULL-UP	Cut to remove the SDA pull-up when chaining modules	—	`SolderJumper-2_P1.3mm_Bridged_RoundedPad1.0x1.5mm`
`JP2`	SCL PULL-UP	Cut to remove the SCL pull-up when chaining modules	—	`SolderJumper-2_P1.3mm_Bridged_RoundedPad1.0x1.5mm`
`R1`	4.7k	I2C SDA pull-up	`RC0603FR-074K7L` Yageo Datasheet ↗	`R_0603_1608Metric`
`R2`	4.7k	I2C SCL pull-up	`RC0603FR-074K7L` Yageo Datasheet ↗	`R_0603_1608Metric`
`R3`	10k	Pull-up for the open-drain INT output	`RC0603FR-0710KL` Yageo Datasheet ↗	`R_0603_1608Metric`
`R4`	100R	Series protection on the sensor-driven INT line	`RC0603FR-07100RL` Yageo Datasheet ↗	`R_0603_1608Metric`
`U1`	APDS-9251-001	Digital RGB + IR color and ambient-light sensor, I2C, interrupt output	`APDS-9251-001` Broadcom Datasheet ↗	`Broadcom_LGA-8_2x2mm_P0.5mm`

Signals#

Net labels used in the schematic, which are also the names the HDL top level should use.

3V3 CLR_INT COLOR_INT GND SCL SCL_PU SDA SDA_PU

Production status#

Schematic ERC	0 violations
PCB layout	complete
DRC	0 violations
Fab package	exported (24 gerbers + drill + CPL + BOM)
Fabricated	no — design stage only

Source: boards/sensor-modules/axs-013-color

Catalog #13 in the AruviX sensor line (../README.md), level L3 (I2C). Uses the APDS-9251-001 instead of the catalog's original TCS34725: no stock KiCad assets exist for the TCS34725, and the APDS-9251 teaches the same color-sensing lesson (four channels, gain/integration control, threshold interrupt) from stock symbols and footprints.

Status: schematic generated, ERC clean (0/0), netlist reviewed. PCB layout not started. Not released.

What it teaches#

Multi-channel I2C data acquisition: R/G/B/IR raw counts, per-channel gain and integration-time trade-offs, color-balance normalization math, and a programmable threshold interrupt.

Design#

Broadcom APDS-9251-001 (LGA-8, OptoDevice:Broadcom_LGA-8_2x2mm_P0.5mm), 100 nF + 1 µF decoupling.
Fixed I2C address 0x52 — no address jumper exists on this part; use bus chaining for multiple color modules.
INT is open-drain: 10 kΩ pull-up on-module (R3), then 100 Ω series (R4) to PMOD pin 1 as COLOR_INT.
4.7 kΩ bus pull-ups through JP1 (SDA) / JP2 (SCL), fitted by default; cut when another module on the chain provides the pull-ups.
Symbol pins 1/4/8 are hidden no-connect substrate pads (nothing to wire).

PMOD pin	1	2	3	4	5	6	7	8	9	10	11	12
Net	COLOR_INT	NC	SCL	SDA	GND	3V3	NC	NC	SCL	SDA	GND	3V3

Regenerate#

python3 generate_design.py

reports/erc.rpt is the last kicad-cli ERC run.

Remaining for release#

[ ] PCB layout (clear optical aperture over U1), DRC, fab outputs
[ ] hdl/: I2C master core, APDS-9251 controller + color-balance math, testbench, ECP5 demo
[ ] BOM export and availability check, design-review checklist