Last updated:
Building an e-ink taplist display for my keezer was a weekend project that has become one of the most commented-on features of my home bar, guests consistently ask about the crisp, paper-like display showing the current lineup of beers with ABV, IBU, and style information. The e-ink display was the right choice over an LCD or LED matrix because it draws essentially zero power when the content isn’t changing, reads perfectly in ambient light without backlighting, and has a quality that matches the aesthetic of a well-crafted bar. The ESP32 microcontroller handles WiFi connectivity and the display updates when I change my Google Sheet taplist from my phone.
E-ink taplist board with ESP32: building a WiFi-connected digital beer menu for your home bar
Why e-ink over LCD or LED for a taplist display: E-ink (electrophoretic) displays use charged pigment particles suspended in a fluid, applying voltage moves the particles to create black or white pixels that stay in position when the voltage is removed. Key advantages for a taplist application: Zero power when static: the display retains its image without power, only consumes power during screen updates (typically 1–3 seconds every hour or when manually triggered). A full day of operation uses less than 100mAh total. Perfect readability: e-ink reflects ambient light like paper, no backlight needed, no glare, visible at any angle. Taplist boards in a bar setting with mixed lighting look professional on e-ink. Aesthetic quality: the paper-like appearance is premium and unusual, it looks like a physical printed sign rather than a screen. Display options for taplist: E-ink module sizes commonly available: 7.5-inch (640×480 pixels, ₹2,500–₹4,000 on Amazon India), 4.2-inch (400×300 pixels, ₹1,200–₹2,000), 2.9-inch (296×128 pixels, smaller, ₹800–₹1,500). For a taplist showing 4–6 beers with name, style, ABV, and IBU: the 7.5-inch display is the minimum for readable text at bar viewing distance (1–2 metres). Manufacturer: Waveshare is the dominant e-ink module manufacturer, their modules have comprehensive ESP32 libraries and documentation. Available on Amazon India and AliExpress. Hardware required: ESP32 development board: the ESP32 combines WiFi, Bluetooth, and sufficient processing power for e-ink display management and HTTP requests. Available in India: Espressif ESP32 DevKit (AliExpress, Amazon India, Robocraze, Evelta), ₹300–₹600. Waveshare 7.5-inch e-ink display (black and white) with SPI interface and HAT adapter for Raspberry Pi, also compatible with ESP32 via SPI. Available from Waveshare India distributors and Amazon India, ₹2,500–₹4,000. SPI connection: e-ink displays connect to ESP32 via SPI interface (5 wires: MOSI, MISO, SCK, CS, DC, and RST + BUSY signals). Waveshare provides pin mapping documentation. Power: ESP32 powered via USB (5V, 500mA), standard USB phone charger. Total hardware cost: approximately ₹3,500–₹5,000 for the complete display assembly. Software architecture, how the system works: The ESP32 connects to home WiFi and periodically fetches taplist data from a Google Sheets spreadsheet (via Google Sheets API or a simple published Google Apps Script web app that returns JSON data). The data is formatted into a display layout and rendered to the e-ink screen. Update frequency: the e-ink update cycle takes 2–3 seconds and has a finite number of full refresh cycles (most Waveshare displays: 1 million full refreshes, more than sufficient for lifetime use at hourly updates). Partial refresh is faster (0.5 seconds) but can cause ghosting on some displays. For a taplist that changes infrequently (once per batch, every few weeks), daily updates are more than sufficient. Google Sheets integration (the simplest data backend): Create a Google Sheet with columns: Beer Name, Style, ABV, IBU, Hops, Notes. Go to Extensions → Apps Script. Paste a simple doGet() function that reads the sheet and returns JSON data. Deploy as a web app (accessible via URL, no authentication for read access). The ESP32 fetches this URL with an HTTP GET request and parses the JSON. When the spreadsheet is updated from any device (phone, laptop), the taplist display updates automatically at the next scheduled refresh. Display rendering on ESP32: Use the Waveshare ESP32 Arduino library (available on GitHub, Waveshare-eInk-ESP32). The library handles the SPI communication and e-ink refresh protocol. Rendering text and layout: use the GxEPD2 Arduino library (widely used, well-documented) which supports Waveshare displays and provides font rendering (FreeSerif, FreeSans fonts included). Layout design: design the layout as code, define screen regions, font sizes, and text positions. For 7.5-inch 640×480 display: header (bar name, current date), 6 beer entries (each showing name in larger font, style/ABV/IBU in smaller font). A custom QR code in the corner linking to the brew log is a nice touch (QR code generation library available for Arduino/ESP32). Physical enclosure: 3D printed frame: a custom frame holding the e-ink display, accessible from any Indian 3D printing service (Sculpteo India, local Bangalore/Mumbai 3D print shops, ₹500–₹1,500 for a basic frame design). Alternatively: a simple picture frame (IKEA or local photo frame) with the display mounted behind the glass, ESP32 tucked behind. Mounting: adhesive strips (3M Command strips) for removable wall mounting, or a small shelf bracket for counter-top display. India-specific notes: Power cuts (load shedding): e-ink retains its image without power, if the power goes out, the taplist remains visible. When power is restored, the ESP32 reconnects to WiFi and resumes scheduled updates. No data loss or display corruption from power interruption. Indian WiFi environments: the ESP32 handles 2.4GHz WiFi, no 5GHz required. Standard home router connectivity with WPA2 security works reliably. Heat management: the ESP32 is rated for 0–85°C operation, no heat management issues in Indian ambient temperatures for an indoor home bar installation.
Common Questions
Can I add colour to the e-ink taplist display, and is a colour e-ink display worth the extra cost?
Colour e-ink displays exist, Waveshare produces 7-colour e-ink displays (black, white, red, yellow, orange, blue, green) at 800×480 resolution. They are worth considering for a taplist but have specific tradeoffs. The advantages of colour: beer style colours (golden for lager, amber for ale, dark for stout), brewery branding, visual differentiation between tap entries. The significant disadvantage: colour e-ink displays update much more slowly than black-and-white, a full colour refresh takes 15–30 seconds (compared to 2–3 seconds for black-and-white). The refresh also looks messy mid-update (cycling through colours before settling). For a taplist that updates hourly or less, this is acceptable, the 15-second update cycle happens infrequently. However, if you plan interactive updates (tap a button to cycle taps, for example), the slow refresh feels unresponsive. The colours in 7-colour e-ink are also limited, they look like watercolour approximations of the target colours, not the vibrant display of an LCD. The palette maps well to beer colours (amber, gold, dark brown) but won’t produce photographic quality. Cost: 7.5-inch colour e-ink modules from Waveshare cost approximately ₹5,000–₹8,000 in India, roughly double the black-and-white equivalent. For a home bar taplist at homebrewing scale, the black-and-white display is the practical recommendation, the text-focused taplist design doesn’t benefit significantly from colour, and the lower cost and faster refresh of black-and-white are genuine advantages. Colour makes more sense for a commercial craft bar taplist where visual differentiation between 20+ taps justifies the cost and the slow refresh is acceptable because updates are infrequent.
