arduino_gauge_controller/VFDStandalone/Pinout.md

Pinout

This project uses an Arduino Mega 2560 with an HV5812P high-voltage shift register / latch driver.

The sketch in VFDStandalone.ino currently expects these logic connections.

Arduino Mega 2560 -> HV5812P

Mega Pin	Mega Function	HV5812P Signal	Notes
D51	MOSI	DATA / DIN	Serial data into the HV5812P
D52	SCK	CLOCK / CLK	Shift clock
D53	SS	LATCH / STROBE	Transfers shifted bits to the outputs
D49	GPIO	BLANK / OE	Optional. Set kHvBlankPin = -1 in the sketch if unused
GND	Ground	Logic GND	Mega and HV5812P logic ground must be common

HV5812P Outputs -> VFD Tube

HV5812P Output	Function
HVOut1	Segment A
HVOut2	Segment B
HVOut3	Segment C
HVOut4	Segment D
HVOut5	Segment E
HVOut6	Segment F
HVOut7	Segment G
HVOut8	Decimal point segment
HVOut9	Alarm bell segment
HVOut10	Digit grid 1
HVOut11	Digit grid 2
HVOut12	Digit grid 3
HVOut13	Digit grid 4
HVOut14	Indicator grid between digits 2 and 3

Serial Input Format

Examples supported by the sketch:

• 1234 -> digits only
• 1234. -> decimal point on
• 1234! -> alarm bell on
• 1234.! -> decimal point and alarm bell on

Power and Safety Notes

• The Arduino 5V pin is for the logic side only.
• The HV5812P also needs its required logic supply and high-voltage supply per the datasheet.
• The VFD filament, grid, and segment high-voltage wiring are separate from the Arduino logic pins.
• Do not connect any high-voltage VFD node directly to the Arduino Mega.
• If the blanking behavior is inverted on your board, change kBlankActiveHigh in the sketch.

Important

This file names the functional signals on the HV5812P, not the package pin numbers. If you want a package-pin wiring table too, I can add one once you confirm the exact datasheet variant / package orientation you are using.