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T-962 ReflowOS

T-962 ReflowOS is a maintained and improved fork of the Unified Engineering T-962-improvements firmware. This project is currently funded and maintained by Schemara.com (the AI-powered PCB & Schematic tools software by Lexithean).

T-962C users: See the T-962C Guide in the wiki for specific firmware settings and hardware fixes.

⚠️ Compatibility: This firmware requires a T-962 with the NXP LPC2134 MCU. Some 2024+ models (V2.0 board) use a different processor and are not compatible. Check your board before flashing.

Features (vs upstream)

This fork merges the following improvements from upstream pull requests that were never merged into the original repo:

Thermocouple & Calibration

  • Finer TC offset steps — 0.10°C instead of 0.25°C for more precise calibration (#235)
  • MAX31855 calibration — TC gain/offset settings now apply to external thermocouple boards (#241)
  • Wider TC offset range — ±12.7°C offset range (was ±25°C with coarser steps) (#245)

Operational Modes

  • SPLIT mode — Uses ambient TC control until a configurable threshold, then switches to PCB-surface thermocouple control for accurate reflow tracking (#136)
  • MAXTEMPOVERRIDE mode — Any TC reading above a threshold overrides the average, useful for sensitive components (#136)
  • Bang-bang heater control — ON/OFF heater drive instead of PID, dramatically improves T-962C heating (fork addition)
  • Preheat phase — Configurable preheat temperature before profile clock starts (fork addition)

Auto-Calibration

  • Bang-bang auto-tune — Runs 3 heat/cool cycles to measure thermal overshoot/undershoot, stores anticipatory offsets with live temperature graph (fork addition)
  • PID auto-tune — Ziegler-Nichols relay method, measures oscillation period/amplitude over 3 cycles to compute optimal Kp/Ki/Kd with live graph (fork addition)
  • TC offset auto-calibration — Uses cold junction sensor as reference at ambient temperature to auto-zero both thermocouples (fork addition)
  • Two-point TC calibration — Separate ambient and high-temp (200°C) offsets per TC, linear interpolation across temperature range for improved accuracy (fork addition)
  • All calibration modes accessible from setup menu or via serial commands (bbtune, pidtune, tccal)

Safety & Control

  • Thermal runaway protection — Aborts reflow/bake if temperature exceeds setpoint by a configurable threshold (0–50°C), with alarm buzzer and error screen (fork addition)
  • Heater failure detection — Serial warning if temperature doesn't rise 5°C in 30s of full heat output (broken SSR/element detection) (fork addition)
  • Cooling rate control — Limits fan speed to prevent thermal shock when cooling rate exceeds a configurable max (0–5.0°C/s) (fork addition)
  • Audible stage alerts — Distinct buzzer melodies for success and safety alarms (fork addition)
  • Time remaining — Countdown timer shown on reflow graph display (fork addition)
  • Post-Reflow Analytics — Displays Peak Temp, TAL (>217°C), and Max Ramp Rate upon completion (fork addition)
  • Fan Kickstart — Optional 250ms full-power pulse on startup to prevent low-speed fan stall (fork addition)
  • Cold start detection — Logs starting temperature and cold/warm status at reflow/bake start (fork addition)

UI Improvements

  • °C/°F temperature toggle — Display temperatures in Celsius or Fahrenheit via settings menu (fork addition)
  • Improved About screen with version info and credits (#159)
  • Screensaver with configurable timeout (#159)
  • Setup menu min/max labels — Shows human-readable limits at range boundaries (#159)
  • Shorter TC labels — Prevents LCD buffer overflow on long offset values (#155)

Stability & Compatibility

  • LCD buffer overflow fix — Prevents crashes from long strings (#245)
  • 1-wire temperature sensor support — DS18B20, DS18S20, and DS1822 all supported for cold junction compensation (#148)
  • Binary serial command interface — CRC-validated protocol for uploading custom profiles via UART (#136)
  • Serial calibration commands — bbtune, pidtune, tccal for headless auto-calibration via UART (fork addition)
  • Serial JSON output — json command toggles machine-readable JSON output for PC graphing/logging tools (fork addition)
  • Text-based profile import — import profile N t1,t2,... for easy profile upload without binary protocol (fork addition)
  • Profile export — export profile N outputs in import-compatible format for round-trip editing (fork addition)
  • Profile naming — name profile N <name> renames CUSTOM profile slots (fork addition)
  • Flash Profile Storage — Up to 32 additional reflow profiles stored in MCU flash (sector 10) via IAP. Serial commands: save flash, delete flash, list flash (fork addition)
  • Profile Backup & Restore — backup command dumps all profiles (EEPROM + flash) as restorable serial text to prevent data loss during firmware updates (fork addition)
  • Enhanced Safety Logic (v2.2) — 'SAFETY ABORT' UI feedback and state reset improvements (fork addition)
  • PlatformIO support — Build with pio run in addition to make (#207)

Build & CI

  • GitHub Actions CI/CD — Automatic firmware builds on push/PR, release artifact upload
  • Node.js 24 compatible — Updated action versions for long-term support

Serial Commands

The serial interface (115200 baud) allows full control and configuration.

Tip

Use the backup command before updating firmware to export your EEPROM profiles as restorable text.

Command Description
help Show all available commands
backup Dump all EEPROM profiles as restorable text
export profile <ID> Export any profile in import format
`import profile <1 2> `
`name profile <1 2> `
bake <Temp> [Time] Enter bake mode at C for [Time] s
json Toggle JSON telemetry output
pidtune / bbtune Start automated heater tuning
tccal Start automated thermocouple calibration

Hardware Improvements

Here are a few improvements made to the T-962 reflow oven utilizing the existing controller hardware:

Replace masking tape

Instructable suggesting replacing masking tape with kapton tape.

Cold junction compensation

The factory firmware assumes a 20°C cold-junction at all times. Add a 1-wire temperature sensor to the TC terminal block for proper compensation. Compatible sensors: DS18B20 (recommended), DS18S20, or DS1822. See the wiki for installation instructions and the Troubleshooting page for wiring details.

Check mains earth connection

Make sure the protective earth wire makes contact with the back panel and that both halves of the oven chassis are connected.

System fan PWM control

The system fan can be speed-controlled via the spare ADO test point. See wiki: system fan PWM mod.

Building

Make (gcc-arm-none-eabi)

See COMPILING.md for toolchain setup.

PlatformIO

pio run

The MCU is an LPC2134/01 (128kB flash / 16kB RAM, 55.296MHz). See the Wiki for flashing instructions.

⚠️ Disclaimer & Support

Use at your own risk. This firmware is provided "as is" without any warranty. Schemara.com and Lexithean assume no liability for any issues, damage to property, or equipment failure resulting from the use of this software.

  • No Professional Support: We do not offer professional or commercial support for this firmware. If you are interested in commercial/professional support please email us at support@lexithean.com.
  • Community Help: While we cannot take liability, we are happy to help via GitHub Issues in any way we can.

Contributing

This firmware runs on T-962, T-962A, and T-962C ovens. Success/failure reports are welcome! Released under GPLv3.

Acknowledgements