1. Introduction
This document provides detailed instructions for the Waveshare 4.2inch E-Ink Display Module. This module features a 400x300 resolution and communicates via an SPI interface. Its design offers ultra-low power consumption, a wide viewing angle, and maintains a clear display without continuous power, making it suitable for applications such as electronic shelf labels and industrial instrumentation.
Figure 1: Front view of the 4.2inch E-Ink Display Module.
2. Features
- No Backlight Required: The display retains its content indefinitely even when power is removed.
- Ultra-Low Power Consumption: Power is primarily consumed only during display refreshes.
- SPI Interface: Facilitates connection with various controller boards, including Raspberry Pi, Arduino, and Nucleo.
- Onboard Voltage Translator: Ensures compatibility with both 3.3V and 5V microcontrollers (MCUs).
- Development Resources: Online user manuals and example code are provided for Raspberry Pi, Jetson Nano, Arduino, and STM32 platforms.
3. What's in the Box
The package includes the following components:
- 1x Waveshare 4.2inch e-Paper Module
- 1x PH2.0 20cm 8Pin Cable
Figure 2: Contents of the package, including the display module and connecting cable.
4. Specifications
| Parameter | Value |
|---|---|
| Display Size | 4.2 inches |
| Resolution | 400 x 300 pixels |
| Display Color | Black / White |
| Grey Scale | 4 |
| Operating Voltage | 3.3V / 5V |
| Interface | 3-wire SPI, 4-wire SPI |
| Outline Dimensions | 103.0mm x 78.5mm |
| Display Area | 84.8mm x 63.6mm |
| Dot Pitch | 0.212 x 0.212 mm |
| Full Refresh Time | Approximately 4 seconds |
| Partial Refresh Time | Approximately 0.4 seconds |
| Refresh Power Consumption | 26.4mW (typical) |
| Standby Power Consumption | <0.017mW |
| Viewing Angle | >170° |
Figure 3: Module overview, interface details, and dimensions.
5. Setup and Connection
The 4.2inch E-Ink Display Module connects to a host microcontroller via a Serial Peripheral Interface (SPI). Ensure correct pin connections to prevent damage to the module or host device.
5.1. Pin Definitions
Refer to the following table and diagram for the pin assignments:
| Pin | Description |
|---|---|
| VCC | Power supply (3.3V-5V) |
| GND | Ground |
| DIN | SPI MOSI (Master Out Slave In) pin |
| CLK | SPI SCK (Serial Clock) pin |
| CS | SPI Chip Select, active low |
| DC | Data/Command selection (High for data, Low for command) |
| RST | External Reset, active low |
| BUSY | Busy status output, active high when busy |
Figure 4: Back of the module with pinout labels (Revision 2.1 shown).
5.2. Connection Procedure
- Identify the corresponding SPI pins (VCC, GND, DIN, CLK, CS, DC, RST, BUSY) on your host microcontroller (e.g., Raspberry Pi, Arduino).
- Connect the included 8-pin cable to the module's connector.
- Carefully connect each wire from the cable to the correct pin on your microcontroller. Double-check all connections before applying power.
- Ensure your microcontroller's logic level is compatible with the module's operating voltage (3.3V or 5V). The onboard voltage translator handles this automatically.
6. Operation
The Waveshare 4.2inch E-Ink Display Module operates on the principle of electrophoretic display technology. This means it does not require a backlight and can hold an image indefinitely without power. Content updates require a refresh cycle, during which power is consumed.
6.1. Display Refresh
- Full Refresh: A complete screen update typically takes around 4 seconds. This clears the entire display and redraws new content.
- Partial Refresh: For minor updates to specific areas of the screen, a partial refresh can be used, which is significantly faster, approximately 0.4 seconds. This mode is useful for dynamic content that changes frequently without needing a full screen clear.
Figure 5: An example image displayed on the E-Ink module.
Figure 6: The E-Ink display module in a blank state.
7. Maintenance
E-Ink displays are generally low-maintenance. To ensure longevity and optimal performance:
- Avoid exposing the display to extreme temperatures or direct sunlight for prolonged periods.
- Do not apply excessive pressure to the display surface.
- Clean the display surface gently with a soft, dry, lint-free cloth. Avoid using liquid cleaners or abrasive materials.
- Store the module in a dry, dust-free environment when not in use.
8. Troubleshooting
If you encounter issues with your E-Ink display module, consider the following common troubleshooting steps:
- No Display/Garbled Output:
- Verify all SPI connections (VCC, GND, DIN, CLK, CS, DC, RST, BUSY) are correct and secure. Incorrect wiring is a common cause of display issues.
- Ensure the power supply to the module is within the specified 3.3V-5V range.
- Check that the correct software library and driver are being used for the 4.2inch 400x300 E-Ink display. Refer to Waveshare's online resources for specific examples.
- Confirm that the reset (RST) and busy (BUSY) pins are correctly handled in your code.
- Slow Refresh Rate:
- Full refreshes are inherently slower than partial refreshes. If you are performing frequent updates, consider implementing partial refresh functionality in your code.
- Ensure your SPI clock speed is configured correctly and is not excessively slow.
- Display Not Clearing Completely:
- Sometimes, residual ghosting can occur. Performing a full refresh cycle multiple times may help clear the display.
- Ensure your software is sending the correct commands for a full clear before drawing new content.
9. Support and Resources
For further assistance, detailed documentation, and development examples, please refer to the official Waveshare online resources. These resources typically include comprehensive user manuals, schematics, and code examples for various platforms like Raspberry Pi, Jetson Nano, Arduino, and STM32.
Visit the Waveshare official website or product page for the latest support information and downloads.
