Sensor modules

AXS-039 — Liquid flow meter carrier PMOD module

Catalog #39 in the AruviX sensor line, level L2 (GPIO, pulse counting). Socketed carrier (same pattern as AXS-046) for a 3-wire hall-effect turbine flow meter of the YF-S201 class.

Level L2 ERC clean DRC clean Fab package 6 components

3D render of the AXS-039 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	Socket decoupling	`GRM188R71C104KA01D` Murata	`C_0603_1608Metric`
`C2`	10uF 10V X5R	Bulk reservoir at the flow-meter socket (cable inductance + hall switching)	`GRM21BR61A106KE19L` Murata	`C_0805_2012Metric`
`J1`	PMOD PLUG 2x6	PMOD peripheral plug (Digilent spec 1.2)	not selected generic	`PinHeader_2x06_P2.54mm_Horizontal`
`J2`	FLOW METER SOCKET	Socket for a 3-wire hall turbine flow meter cable, pin order VCC/SIGNAL/GND	not selected generic	`PinSocket_1x03_P2.54mm_Vertical`
`R1`	10k	Pull-up for the meter's open-collector hall output	`RC0603FR-0710KL` Yageo Datasheet ↗	`R_0603_1608Metric`
`R2`	100R	Series protection on the module-driven FLOW line	`RC0603FR-07100RL` Yageo Datasheet ↗	`R_0603_1608Metric`

Signals#

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

3V3 FLOW FLOW_RAW GND

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-039-flow

Catalog #39 in the AruviX sensor line (../README.md), level L2 (GPIO, pulse counting). Socketed carrier (same pattern as AXS-046) for a 3-wire hall-effect turbine flow meter of the YF-S201 class.

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

What it teaches#

Frequency as a measurand: the turbine's hall sensor pulses at a rate proportional to flow. Count pulses per gate interval, apply the meter's K-factor (YF-S201 class: roughly f ≈ 7.5 × Q with f in Hz and Q in L/min, i.e. ~450 pulses per litre), and calibrate K yourself with a measuring jug — calibration is part of the lesson.

Design#

J2 is a 1×03 pin socket, pin order VCC / SIGNAL / GND, matching the usual red/yellow/black flow-meter pigtail.
Check your meter runs at 3.3 V. The classic YF-S201 is specified 5–18 V; use a 3.3 V-capable variant or a unit you have verified at 3V3. Never feed 5 V through the PMOD rail.
The hall output is open-collector: 10 kΩ pull-up on-module, then a 100 Ω series resistor to PMOD pin 1 (FLOW). Idles high, pulses low.
100 nF + 10 µF at the socket (long cable + switching hall sensor).

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

Regenerate#

python3 generate_design.py

Remaining for release#

[ ] PCB layout (20 × 25 mm outline), DRC, fab outputs
[ ] hdl/: gated pulse counter + fixed-point K-factor scaler, testbench
[ ] Pin a 3.3 V-capable meter part number; BOM export, design review