This 3D-printed test jig provides a stable, integrated platform for the Pico Breadboard Kit and a 2.42-inch OLED Display, streamlining the prototyping workflow for Raspberry Pi Pico and Pico W projects. Designed with precision in SHAPR3D, the chassis features dedicated mounting points for the breakout board, ensuring the LED indicators and buttons remain easily accessible during firmware testing. The 128x64 SSD1309 OLED module is elevated via custom-fitted spacers, providing optimal visibility and preventing stress on the 4-pin I2C header connections. By consolidating these components into a single, rigid unit, the jig eliminates intermittent wiring issues and protects the hardware during bench testing and transport.

I have included a MicroPython Code in a ZIP file for you to test the OLED display.   This script uses the default machine.I2C peripheral.

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Key Technical Features

• Integrated Mounting: Secure snap-fit or screw-down points for the Pico Breadboard Kit.
• OLED Elevation: Custom 3D-printed spacers to align the 2.42" display with the user's line of sight.
• Material Optimization: Designed for PLA or PETG printing on the Bambu Labs A1 and P1S, ensuring high dimensional accuracy for the SSD1309 module footprint.
• Access Cutouts: Full clearance for the Pico’s micro-USB/USB-C port and the breadboard's onboard peripherals (buzzer, buttons, and LEDs).

Recommended Print Settings (A1 and P1S)

• Material: PLA (for rigidity) or PETG (if you want more "snap" in the clips).
• Infill: 15% Gyroid (provides excellent support for the mounting holes).
• Wall Loops: 3 (essential for the screw holes to prevent stripping).
• Layer Height: 0.2mm (standard) or 0.12mm (if the spacer tolerances are tight).

Most of the 2.42-inch SSD1309 OLED modules from AliExpress that are configured for 4-pin I2C use a slightly different initialization than the standard 0.96-inch screens. Specifically, they often require the Reset (RES) pin to be pulsed high during startup to "wake up" the controller, even if the module only has four main pins (VCC, GND, SCL, SDA).   If your module has a Reset pin, I've included it below. If it truly only has 4 pins, you can omit the reset logic.

Troubleshooting Tips for the 2.42" OLED Module

• The "I2C Jumper": Many of these large OLEDs arrive from AliExpress hard-wired for SPI. Look at the back of the PCB—you may need to desolder a zero-ohm resistor from the "SPI" position and move it to the "I2C" position.
• Address Resistor: On the back of the board, there is often a resistor labeled DC/Address. Depending on its position, the I2C address will be either 0x3C or 0x3D. The i2c.scan() part of the code above will confirm this for you in the Thonny console.
• Pull-up Resistors: The Pico Breadboard Kit usually handles basic connections, but if the display is glitchy, ensure the I2C lines have pull-up resistors (though the SSD1309 modules typically have 4.7kΩ resistors built-in).

Connect these from your Pico Breadboard Kit to the OLED: