Sensor modules

AXS-021 — Ultrasonic ranger carrier PMOD module

Catalog #21 in the AruviX sensor line, level L2 (trigger/echo pulse timing).

Level L2 ERC clean DRC clean Fab package 6 components

3D render of the AXS-021 PCB — Rendered from the PCB layout. No physical board has been manufactured.

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	Transmit-burst bulk reservoir at the ranger socket	`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`	RCWL-1601 SOCKET	Socket for a 3.3 V HC-SR04-form-factor ultrasonic ranger	not selected generic	`PinSocket_1x04_P2.54mm_Vertical`
`R1`	100R	Series protection on the ranger-driven ECHO line	`RC0603FR-07100RL` Yageo Datasheet ↗	`R_0603_1608Metric`
`R2`	10k	TRIG pull-down so an unconfigured host pin cannot false-trigger a burst	`RC0603FR-0710KL` Yageo Datasheet ↗	`R_0603_1608Metric`

Signals#

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

3V3 ECHO ECHO_RAW GND TRIG

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-021-ultrasonic

Catalog #21 in the AruviX sensor line (../README.md), level L2 (trigger/echo pulse timing).

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

What it teaches#

Pure counter/FSM timing: emit a 10 µs TRIG pulse, then measure the ECHO high time (≈58 µs per cm) and convert to distance in fabric.

Design#

This is a carrier: the transducer pair stays a plug-in module. J2 is a 1×4 socket in HC-SR04 pin order (VCC / Trig / Echo / GND) sized for the Adafruit RCWL-1601, the 3.3 V version of the HC-SR04.

Warning: classic 5 V-only HC-SR04 modules must not be fitted. The carrier provides a 3.3 V rail only, and a 5 V ECHO would stress the host even through the series resistor.

100 Ω series on the ranger-driven ECHO line.
10 kΩ pull-down on TRIG so an unconfigured host pin can't false-trigger.
10 µF reservoir for the transmit-burst current draw.

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

Regenerate#

python3 generate_design.py

Remaining for release#

[ ] PCB layout (20 × 40 mm outline — socket + plug-in clearance), DRC, fab
[ ] hdl/: trigger/echo timer core, testbench, ECP5 demo
[ ] BOM export and availability check, design-review checklist