Circuit Design Academy 8 Modules Interactive

RS232 · RS485 · RS422
Serial Interface Hardware Design from Signal to PCB

A complete, hands-on guide to the three workhorse serial interfaces. See why a differential pair beats a single-ended line for noise and distance, compare voltage levels, cable length and data rate on live Plotly charts, wire up DE-9 and terminal blocks correctly, protect connectors against ±8 kV ESD, terminate and bias an RS485 bus, pick the right transceiver, and lay out controlled-impedance differential pairs on the board.

8
Modules
5+
Interactive Tools
Plotly
Live Charts
3
Interfaces Compared

Course Modules

All eight modules are fully available — each with interactive animations, calculators or live charts, worked diagrams, and a knowledge check.

01
Introduction & Interface Comparison
Single-ended vs differential signaling, how common-mode noise is rejected, the full RS232/RS485/RS422 comparison table, a live baud-rate-vs-cable-length Plotly chart, and a "which interface should I use?" decision guide.
Available~50 min
02
Signal Levels, Voltage & Duplex Modes
RS232 ±3–15 V logic, RS485/RS422 differential ±1.5–5 V, mark/space definitions, common-mode range, and full- vs half-duplex operation.
Available~45 min
03
Connectors & Pinouts
DE-9 (DB9) RS232 pinout, RS485/RS422 terminal block and RJ45 conventions, A/B and D+/D− naming, the Y/Z second pair, and the vendor A/B ambiguity trap.
Available~40 min
04
ESD Protection Front-End
TVS diode topology per line, uni- vs bidirectional selection, placement at the connector before series R/ferrite, IEC 61000-4-2 ±8 kV levels, and the connector → TVS → series → transceiver schematic.
Available~45 min
05
Termination & Fail-Safe Biasing
120 Ω termination at each bus end, why it matches twisted-pair impedance, fail-safe pull-up/pull-down bias resistors, and the idle-bus indeterminate-state problem.
Available~45 min
06
Transceiver IC Selection
RS232 charge-pump parts (MAX232 family), RS485/422 half-duplex with DE/RE control vs full-duplex, and slew-rate-limited vs high-speed transceivers.
Available~45 min
07
PCB Layout & Cabling
Controlled-impedance ~120 Ω length-matched differential pairs, ground-plane continuity, TVS tight to the connector, shielded twisted pair, and one-end shield grounding.
Available~45 min
CS
Standards, Isolation & Decision Guide
Isolated transceivers and digital isolators, multidrop daisy-chain topology, half-duplex turnaround timing, failure modes, the TIA/EIA and IEC standards footer, and a capstone selection challenge.
CapstoneAvailable~50 min

Prerequisites

This course assumes basic familiarity with serial communication. You should be comfortable with:

UART / serial basics (start bits, baud rate, TX/RX)
Ohm's law, voltage dividers, and basic circuit analysis
Digital logic levels and microcontroller I/O basics
Reading component and product datasheets