TRMNL Content Generator

Generate HTML content for TRMNL e-ink display devices.

Quick Start Workflow

Check for $TRMNL_WEBHOOK environment variable

If missing, prompt user for webhook URL

Ask user to verify TRMNL display markup is set to:

{{content}}

Confirm device type (default: TRMNL OG, 2-bit, 800x480)

Read relevant reference docs based on content needs

Generate HTML using TRMNL framework classes

Send via POST to webhook (use temp file method)

Send minimal confirmation only - Do NOT echo content back to chat

Device & Setup

Default target: TRMNL OG (7.5" e-ink, 800x480px, 2-bit)

Display markup required:

<div>{{content}}</div>

Webhook:

export TRMNL_WEBHOOK=""

Sending content (temp file method):

cat > /tmp/trmnl.json << 'EOF'
{"merge_variables":{"content":"<div class=\"layout\">HTML</div>"}}
EOF
curl "$TRMNL_WEBHOOK" -H "Content-Type: application/json" -d @/tmp/trmnl.json -X POST

Webhook Limits

Tier

Payload Size

Rate Limit

Free	2 KB (2,048 bytes)	12 requests/hour
TRMNL+	5 KB (5,120 bytes)	30 requests/hour

Check payload size before sending:

python3 scripts/check_payload.py /tmp/trmnl.json

Tips to reduce payload size:

• Minify HTML (remove unnecessary whitespace)


• Use framework classes instead of inline styles


• Use short class names the framework provides


• Remove comments from HTML


• Use deep_merge strategy for incremental updates

Reference Documentation

Read these files as needed:

File	When to Read

references/patterns.md	Start here - Common plugin patterns from official examples
references/framework-overview.md	Device specs, e-ink constraints, responsive prefixes
references/css-utilities.md	Colors, typography, sizing, spacing utilities
references/layout-systems.md	Flexbox, grid, overflow/clamp engines
references/components.md	Title bar, dividers, items, tables, charts
references/webhook-api.md	Payload format, rate limits, troubleshooting
assets/anti-patterns.md	Common mistakes to avoid
assets/good-examples/	HTML reference implementations

Scripts:

Script

Purpose

scripts/check_payload.py

Verify payload size before sending (run on /tmp/trmnl.json)

Standard Plugin Structure

Every plugin follows this pattern:

<div class="layout layout--col gap--space-between">
  <!-- Content sections separated by dividers -->
</div>
<div class="title_bar">
  <img class="image" src="icon.svg">
  <span class="title">Plugin Name</span>
  <span class="instance">Context</span>
</div>

• layout + layout--col = vertical flex container
• gap--space-between = push sections to edges
• title_bar = always at bottom, outside layout
• divider = separate major sections
• CRITICAL: Only ONE .layout element per view (no nesting)

Grid System (10-Column)

Column spans should sum to 10:

<div class="grid">
  <div class="col--span-3">30%</div>
  <div class="col--span-7">70%</div>
</div>

Simple equal columns: grid--cols-2, grid--cols-3, etc.

Item Component

Standard data display pattern:

<div class="item">
  <div class="meta"><span class="index">1</span></div>
  <div class="content">
    <span class="value value--xlarge value--tnums">$159,022</span>
    <span class="label">Total Sales</span>
  </div>
</div>

Value Typography

Always use value--tnums for numbers.

Class

Usage

value--xxxlarge	Hero KPIs
value--xxlarge	Large prices
value--xlarge	Secondary metrics
value--small	Tertiary data
value--tnums	Always for numbers

Auto-fit: ...

Columns (for Lists)

<div class="columns">
  <div class="column" data-overflow="true" data-overflow-counter="true">
    <span class="label label--medium group-header">Section</span>
    <div class="item">...</div>
  </div>
</div>

Grayscale Dithering

Use dithered classes, not inline gray colors:

• bg--black, bg--gray-60, bg--gray-30, bg--gray-10, bg--white


• text--black, text--gray-50

Data Attributes

Attribute

Purpose

data-fit-value="true"	Auto-resize text to fit
data-value-format="true"	Auto-format numbers (locale-aware)
data-clamp="N"	Limit to N lines
data-overflow="true"	Enable overflow management
data-overflow-counter="true"	Show "and X more"
data-overflow-max-cols="N"	Max columns for overflow
data-content-limiter="true"	Auto-adjust text size
data-pixel-perfect="true"	Crisp text rendering
data-table-limit="true"	Table overflow with "and X more"

Label & Title Variants

<span class="label label--small">Small</span>
<span class="label label--medium">Medium</span>
<span class="label label--underline">Underlined</span>
<span class="label label--gray">Muted/completed</span>
<span class="title title--small">Compact title</span>

Gap Utilities

gap--space-between | gap--xxlarge | gap--xlarge | gap--large | gap--medium | gap | gap--small | gap--xsmall | gap--none

Typography Guidelines

Recommended: Georgia serif font for e-ink readability.

Content-aware sizing:

• Short content = bigger fonts (24-28px body)


• Long content = smaller fonts (20px body)


• Headings: 36-48px

User Experience

Critical: Do NOT echo content back to chat. Just confirm "Sent to TRMNL".

Anti-Patterns

Tiny fonts for short content

Center-aligning columns with different lengths (use layout--start)

Spoiling content in chat confirmation

Missing value--tnums on numbers

Missing title_bar

Not using data-fit-value on primary metrics

Skipping data-overflow on variable lists

Using inline gray colors instead of bg--gray-*

Forgetting dividers between sections

Best Practices

Verify

{{content}}

display markup

Use layout + title_bar structure

Always value--tnums for numbers

Use data-fit-value on primary metrics

Use data-overflow on variable lists

Use item component pattern

Use divider between sections

Use bg--gray-* dithered classes

Content-aware font sizing

Top-align columns (layout--start)

Temp file method for curl

Minimal confirmations

Mashup Layouts (Multi-Plugin)

For dashboard views with multiple plugins:

Layout

Description

mashup--1Lx1R	2 columns (50/50)
mashup--1Tx1B	2 rows (50/50)
mashup--2x2	4 quadrants

See references/layout-systems.md for all 7 layouts.

Troubleshooting

Problem

Solution

Webhook fails	Verify URL, check rate limits (12/hour free)
Content missing	Check display markup is {{content}}
Payload too large	Run scripts/check_payload.py, keep under 2KB (free) or 5KB (TRMNL+)
Numbers misaligned	Add value--tnums
Text overflow	Use data-clamp or data-overflow
Columns misaligned	Use layout--start not layout--center
Multiple layouts error	Keep only ONE .layout element per view
Nested content fails	Use .richtext for nested/formatted content