7 Segment Display Calculator
Preview segment lighting, calculate resistor values, and validate multiplex timing in one UI. Share firmware-ready lookup tables for common cathode or common anode displays within seconds.
Live preview
See the seven-segment output with the correct polarity for your wiring mode.
Multiplex profile
- Duty cycle per digit
- 25%
- Refresh per digit
- 60 Hz
- Configuration
- 4 digits @ 240 Hz
Firmware lookup table
const sevenSegMask = 0x004F5B06;Split the hex mask into bytes for Arduino/STM32 arrays or export directly as a .coe file for FPGA designs.
Export & debug
- • HEX mask: 0x004F5B06
- • Binary mask: 0b00000000010011110101101100000110
- • Series resistor: 161.11 Ω
- • Logic mode: Common cathode
Action required
- Click “Generate segment map” to lock the current configuration and export code.
How to use this 7 segment display calculator
Get wiring-ready data in three quick steps.
- Choose the input and wiring
Select decimal, hex, or binary input and set the display wiring to common cathode or common anode so the logic polarity is correct.
- Configure multiplex parameters
Set digit count, refresh rate, and LED electrical ratings. The app warns if duty cycle or voltage limits are unsafe.
- Generate and export
Click Generate to lock the configuration, copy the lookup mask, and share the parameters with firmware teammates.
Case study: Stabilising an industrial counter display
A manufacturing engineer needs to refurbish a four-digit production counter with modern drivers while keeping the existing 7 segment hardware.
- Display
- Legacy 4-digit common anode module
- Controller
- STM32 microcontroller with timer interrupts
- Challenge
- Flicker at low refresh rates and overheating resistors
- Map hexadecimal counts
The engineer enters hex values to confirm segment masks align with the existing PLC displays.
- Tune multiplex speed
They increase refresh to 320 Hz, keeping per-digit frequency above 80 Hz to remove flicker warnings.
- Balance current draw
Adjusting LED current from 20 mA to 12 mA raises the recommended resistor, preventing thermal runaway.
Result
The counter ships with stable brightness, compliant current limits, and annotated firmware arrays generated from the calculator.
7 segment display FAQ
Does the calculator handle custom segment orders?
The current release assumes the standard A–G segment order. For bespoke PCBs, share the exported hex mask with your firmware team and remap bits as needed.
How should I set the refresh rate?
Aim for at least 60 Hz per digit. For four digits that means 240 Hz overall. The warning banner triggers whenever the per-digit rate falls below the comfort threshold.
Can I share configurations with teammates?
Yes. Copy the generated masks and parameter summary into your documentation or version control to keep hardware, firmware, and QA aligned.
What about segments beyond hexadecimal?
Future updates will add customizable glyph libraries. For now, combine the binary mask output with custom lookup tables for characters outside 0–F.
Will this work with driver ICs?
Absolutely. Use the hex mask for direct MCU control or translate it for driver IC pinouts such as MAX7219 or TM1637.
How do I apply the recommended resistor value?
Use the calculated resistor as the closest standard value per segment in single-digit applications. For multiplexed displays, treat it as the per-segment series resistor.
Can I lower the LED current?
Yes. Drop the current to reduce power draw or meet thermal limits—the calculator instantly updates the suggested resistor.
Does the tool cover temperature derating?
It highlights overcurrent risks. For precise thermal analysis, combine the resistor output with your LED datasheet’s derating curves.
Is there a dark mode?
Yes. The interface inherits the site-wide dark mode, making it easier to reference on the bench in low-light labs.
How often should I re-run the calculator?
Whenever you change digit count, refresh rate, or LED characteristics. The warnings ensure each new configuration stays within spec.
Reference resources
- Arduino seven-segment display guide
- MAX7219 LED driver application note
- FPGA .coe file reference