Interactive Connector Pinout Reference
Pin-level diagrams with signal names, electrical specs and wire colours
Interactive Connector & Pinout Guide
Select a common connector type to view its pin-level diagram. Click any pin on the SVG diagram to inspect its signal name, electrical specification, and wire color standard.
Notes on These Connectors
A pinout on its own rarely settles a repair — what matters is which pins are load bearing, which are optional, and which will happily destroy something if you get them the wrong way round. The diagrams above give signal names, electrical specifications and wire colours; the notes below cover the parts that catch people out.
USB Type-C
The reversible shell means most signals appear twice, so a connector can be physically intact and still fail on one orientation only — a classic sign of a cracked solder joint on one side. The pins that decide behaviour are CC1 and CC2: a plain sink identifies itself with 5.1 kΩ pull-downs on those lines, and a cable or device that charges in one orientation but not the other usually has a CC fault rather than a power fault. VBUS and GND are deliberately multiplied for current sharing, so do not assume a single continuity check proves the whole rail.
RJ45 and T568B
Pairing, not pin order, is what makes Ethernet work. In T568B, pins 1–2 carry the orange pair and 3–6 the green pair, which is why pin 6 sits away from pin 3 and why an otherwise tidy-looking punch-down that splits those pairs will pass a continuity test and then fail at speed. 10 and 100 Mbit links use only 1–2 and 3–6, so a cable with damaged blue or brown pairs can run at 100 Mbit and refuse to negotiate gigabit — a very common field symptom.
DB9 RS-232
On a DTE device pin 2 is receive, pin 3 is transmit and pin 5 is signal ground; DCD, DTR, DSR, RTS, CTS and RI fill the rest. Two devices of the same type need their transmit and receive lines crossed, which is all a null-modem cable is. Remember that true RS-232 swings well beyond logic levels — often ±12 V — so wiring one directly to a 3.3 V microcontroller pin without a level shifter destroys the pin.
HDMI Type A and ESP32 DevKit
HDMI carries three TMDS differential pairs plus a clock pair, and because those are impedance-controlled, damage usually shows as one missing colour channel or sparkle rather than a dead display. The DDC lines, CEC on pin 13 and hot-plug detect on pin 19 are what let a sink be recognised at all — a display that shows nothing while the source claims no device attached is a hot-plug or DDC problem, not a video one. On the ESP32 DevKit, GPIO6–11 are wired to the internal SPI flash and must be left alone, GPIO34–39 are input only with no output drivers or pull-ups, and the ADC2 channels are unavailable while Wi-Fi is active — the reason a working analogue read mysteriously returns zero once networking is enabled.