Sensor modules

AXS-043 — CCS811 eCO2/TVOC gas-sensor PMOD module

Catalog #43 in the AruviX sensor line, level L3 (I2C). Uses the CCS811 instead of the catalog's original ENS160: no stock KiCad assets exist for the ENS160, and the CCS811 teaches the same eCO2/TVOC air-quality lesson (metal-oxide sensing, baseline management, wake/interrupt handshaking) from stock symbols and footprints.

Level L3 ERC clean DRC clean Fab package 13 components

3D render of the AXS-043 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`	10uF 10V X5R	Bulk reservoir for the pulsed MOX heater supply	`GRM21BR61A106KE19L` Murata	`C_0805_2012Metric`
`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`
`JP3`	~WAKE SEL	~WAKE source: 1-2 GND always awake (default), 2-3 host-driven ECO2_WAKE_N on PMOD pin 2	—	`SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mm`
`JP4`	ADDR 0x5A/0x5B	I2C address select: 1-2 ADDR low 0x5A (default), 2-3 ADDR high 0x5B	—	`SolderJumper-3_P1.3mm_Bridged12_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`
`R5`	10k	~RESET pull-up (on-module only; not routed to the PMOD - use I2C SW_RESET)	`RC0603FR-0710KL` Yageo Datasheet ↗	`R_0603_1608Metric`
`U1`	CCS811	Digital eCO2 and TVOC gas sensor, I2C, on-chip MCU with baseline engine	`CCS811B-JOPD500` ams (ScioSense) Datasheet ↗	`AMS_LGA-10-1EP_2.7x4mm_P0.6mm`

Signals#

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

3V3 ADDR CCS_INT_N ECO2_INT_N ECO2_WAKE_N GND RESET_N SCL SCL_PU SDA SDA_PU WAKE_N

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-043-eco2

Catalog #43 in the AruviX sensor line (../README.md), level L3 (I2C). Uses the CCS811 instead of the catalog's original ENS160: no stock KiCad assets exist for the ENS160, and the CCS811 teaches the same eCO2/TVOC air-quality lesson (metal-oxide sensing, baseline management, wake/interrupt handshaking) from stock symbols and footprints.

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

What it teaches#

A stateful I2C driver well beyond raw register reads: application-mode boot (APP_START), measurement-mode selection, the data-ready interrupt, and baseline save/restore across power cycles — plus the ~WAKE handshake when the host manages sensor power.

Design#

ams (ScioSense) CCS811B-JOPD500, LGA-10 (Package_LGA:AMS_LGA-10-1EP_2.7x4mm_P0.6mm).
Decoupling: 100 nF + 10 µF 0805 bulk — the MOX heater is pulsed.
~WAKE (JP3, 3-way): 1-2 GND (default) = always awake, simplest bring-up; move to 2-3 to hand ~WAKE to the host on PMOD pin 2 (ECO2_WAKE_N).
~INT is open-drain: 10 kΩ pull-up on-module (R3), then 100 Ω series (R4) to PMOD pin 1 as ECO2_INT_N.
~RESET: 10 kΩ pull-up on-module only, not routed to the PMOD — use the I2C SW_RESET mailbox for resets.
Address (JP4): 1-2 GND = 0x5A (default), 2-3 VDD = 0x5B.
PWM/Sense (the optional external-NTC network) and AUX are left floating per the datasheet (no-connect markers).
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.

PMOD pin	1	2	3	4	5	6	7	8	9	10	11	12
Net	ECO2_INT_N	ECO2_WAKE_N	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 (thermal relief: keep the MOX package away from other heat sources; opening over the sensor mesh), DRC, fab outputs
[ ] hdl/: I2C master core, CCS811 controller (boot FSM + baseline), testbench, ECP5 demo
[ ] BOM export and availability check, design-review checklist