Measurement is a system
Sensor-Node PCB Design
Design a sensor node around power integrity, interface constraints, address conflicts, placement, calibration, and observable failure modes.
Short answer
A sensor node is not finished when the sensor answers once on a development board. The PCB must preserve the sensor’s supply, thermal environment, address and bus timing, placement constraints, and calibration assumptions while giving firmware enough observability to distinguish a dead part from a bad measurement.
Design sequence
Step 1
Define the quantity and environment
Specify range, accuracy, sample rate, temperature, airflow, vibration, contamination, and whether the board itself changes the thing being measured.
Step 2
Choose the interface deliberately
I²C saves pins but creates address and pull-up constraints. SPI spends pins for timing margin. One-wire interfaces simplify cabling but bring topology and timing limits.
Step 3
Protect measurement integrity
Place decoupling at the device, keep heat sources and noisy switching nodes away, respect package openings and keep-outs, and verify logic levels at both ends of the bus.
Step 4
Make faults observable
Record device identity, raw readings, status registers, bus errors, and reference measurements before applying filters or calibration that can hide the failure.
Stop conditions
- Stop if the selected part cannot meet the required range or accuracy over the actual environmental corners.
- Stop if placement, self-heating, address selection, pull-ups, bus voltage, or counterfeit risk has no explicit design treatment.
Choose each subsystem
Sensors
Environmental, motion, and current sensors: address pins, self-heating, counterfeit detection, and interface modes.
Interface ICs
USB bridges, transceivers, expanders, and level shifters: driver situations, reference pins, and bus speed limits.
Microcontrollers
MCUs and MCU modules: minimal circuits, strapping and boot pins, clock requirements, and the supply gotchas that cause field failures.
Voltage Regulators
Linear regulators and references: dropout, stability requirements, quiescent current, and thermal limits.
Verified part guides
These pages establish exact part boundaries and datasheet-backed constraints. They are examples and design references, not a universal BOM.
- BME280Combined temperature humidity and pressure sensor on I2C or SPI
- DS18B201-Wire digital temperature sensor; heavily counterfeited.
- MPU-60506-axis accelerometer and gyro; GY-521 module chip; clones dominate supply
- INA219Bidirectional I2C current, voltage, and power monitor for rails up to 26 V.
- ADS111516-bit I2C delta-sigma ADC with PGA, comparator, and a four-input mux.
- RP2040Dual Cortex-M0+ 133 MHz MCU with 264 KB SRAM and external QSPI flash.
Take it to the bench
Questions to take into PCBWiki
- Which sensor interface is safest for this cable length and sample rate?
- How do I separate sensor self-heating from a real temperature change?