Introduction

HTLabeler is a progressive web application (PWA) designed to generate and print Holding Time food safety labels directly to Bluetooth thermal printers. It operates entirely in your browser, utilizing standard Web Bluetooth APIs.

The system is designed for high-speed kitchen environments, allowing staff to instantly calculate expiration times based on preset product rules and dispatch them to the printer with zero latency.

Connecting the Printer

HTLabeler connects directly to your Bluetooth thermal printer using standard WebBLE.

1. Navigate to the Config & Setup tab using the sidebar.
2. Locate the Hardware Link panel.
3. Click Connect. A browser-native Bluetooth pairing menu will appear.
4. Select your thermal printer from the list.

Finding Your Printer's UUID (nRF Connect)

If your printer pairs properly but the app throws an error stating it cannot find a writable characteristic, it likely uses a non-standard custom Bluetooth Service UUID. You can extract this exact UUID using a free diagnostic app called nRF Connect.

1. Download nRF Connect for Mobile from the iOS App Store or Google Play Store.
2. Turn on your thermal printer and ensure Bluetooth is enabled on your mobile device.
3. Open nRF Connect and tap the Scan button to locate your printer, then tap Connect next to it.
4. Once connected, swipe over to the Client tab. This displays a list of all services broadcast by the printer.
5. Look for a service labeled as "Unknown Service" or similar (usually not one of the standard Generic Access services). Tap it to expand its list of characteristics.
6. You are looking for a characteristic row that lists the Write or Write Without Response property.
7. Copy the 128-bit UUID of the parent Service (the top-level heading, e.g., 000018f0-0000-1000-8000-00805f9b34fb) and paste it directly into the Registered UUIDs configuration in HTLabeler.

Quick Print

The Quick Print tab is designed for single-item dispatch. Simply select a category from the top drag-scrollable tabs, and tap any item card to instantly queue and print a single label based on the current time.

Batch Print

For bulk prepping, Batch Print allows you to adjust the quantities of multiple distinct items simultaneously.

• Use the + and - buttons on item cards to build your queue.
• Click 1 All (Active) to quickly add 1 quantity to every item in the currently viewed category.
• Once items are queued, a floating Print Batch button appears at the top right of the view.
• Upon clicking print, a modal will appear allowing you to override the Base Made Time for the entire batch.

Macro Batch

Macros are saved templates of Batch Prints. If you print the exact same 15 items every morning, you can create a "Morning Prep" macro to trigger them all with one click.

Creating/Editing a Macro

In the Macro Editor, the screen is split into two columns:

• Right Column (Available): Browse categories and add items to your macro.
• Left Column (Selected): View your currently bundled items. You can adjust quantities, delete items, and drag-and-drop the cards to reorder the exact sequence the labels will print from the machine.

Custom Label

The Custom Label module provides a live canvas preview, allowing you to manually type in product names, temperatures, and explicitly define Made/Ready/Discard times.

Features:

• Load Preset: Quickly populate the custom fields with data from an existing Database Item.
• Recalc Button: If you manually change the "Made Time", clicking the "Recalc" button will automatically update the Ready and Discard times based on the loaded preset's duration rules.
• EOD Override: Checking the "EOD" box forces the label to display DD/MM EOD (End of Day) instead of a specific timestamp, bypassing standard expiration mathematics.

Remote Synchronization

If an enterprise maintains a master JSON configuration file hosted on a remote server, you can input the URL into the Remote Preset Sync input field.

Enabling Auto-Sync on Setup will automatically trigger a background fetch update to guarantee the device has the latest food safety times every time the user navigates to the setup tab. Note: Syncing fully overwrites local items and categories, but preserves personal Macros and PICs.

Speed Tweaks (Danger Zone)

Found at the bottom of the Setup tab, these toggles alter fundamental hardware communication logic.

System Log

The System Log is a diagnostic tool that records every internal event. This is crucial for hardware debugging. It logs:

• Specific BLE UUIDs polled during printer pairing sequences.
• Exact parameters applied to a label execution (e.g., M: 05/11 14:00 | R: 05/11 14:30 | D: EOD)
• Settings updates and remote sync HTTP errors.